ipt_notes

IPT notes by bluecrisps

9.1 Project management

Techniques for managing a process Communication skills necessary for dealing with others

Active listening: Paying attention to what the person is saying and letting them know you are listening by either asking questions or paraphrasing

Conflict resolution: To stop conflicts which have happened through negotiations Negotiation skills: Persuading the people in the conflict to calm down and resolve

the conflict by working out a win-win situation Interview techniques: Asking the right questions Team building: Working collaboratively and enjoy working with each other

The consequences of a group that fail to manage to work well Financial loss: Money will be lost through time wasted. Both sides of the party will

be affected by this as time can be spent on completing the job and finding a new job for the developers and for the clients they can start using the new system which should bring more profit or save money

Employment loss: The contract may be cancelled causing a loss in the developing team’s employment

Missed opportunities: Time is wasted for the team and the team may be too busy wasting time on negotiation and conflict resolution and can miss opportunities such as a new client, an easier way to develop the system and other opportunities

Project management tools Gantt charts

Bar graph displaying the amount of time it will take to complete the project, using steps from the system development cycle UPDIT (Understanding, Planning, Designing, Implementing, Testing)

Scheduling of tasksTasks are allocated to different people and there is a set time they are allowed to work on it. The Gantt chart shows the schedule of the project plan

Journals and diaries: journals and diaries are kept and people write down what they have done or what they hope to achieve to do to manage their time.

Funding management plan: Talks about the funds being used and how it will be used in parts of the system. It details the time and how the money will be released and also who is responsible for buying or using those funds.

Communication management plan: Specifies how people in the system communicate with each other. Explains who people should contact when they have questions.

Identifying social and ethical issues Privacy and copyright (existing data can be used to test the assist the

development of the system and it could contain private, personal data or data taken from someone else)

OHS issues while using UPDIT for developers and using the actual system for participants. During the development phase there can be OHS issues if the technology the developers use is hazardous or the workplace is hazardous. The new system can cause danger to participants if it is faulty and the environment in which the participants are can cause harm if it is not safe.

Security of data during the development of the system. The data used in the system must be protected from outside use. Such data include the requirements report, prototype system and simulation data.

Understanding the problem Approaches to identify problems with existing systems. To find out problems

with the existing system the following steps can be taken: interviewing/surveying users of the information system interviewing/surveying participants analysing the existing system by determining:

o how it workso what it doeso who uses it

Requirements report A document which states the requirements of the new system, problems with the

old, solutions to problems and Gantt charts with information on when and how it will be implemented

Requirements prototype– Used when the problem is not easily understood– Repetitive process of prototype modification and participants’ feedback until the problem is understood– Can be the basis for further system development

Planning a feasibility study of proposed solutions checks the benefits of the new system, including:

Technical feasibility: Checks if the required information technology is available already or can be purchased and also if the users or participants can operate the new system. It also checks whether programmers, testers and debuggers are available to develop or maintain the system

Economic feasibility: Determines how much it will cost and the profit from the new system compared to the old one. A cost-benefit analysis is used to find out what costs will be incurred in the system and what benefits it will produce.

Schedule feasibility: Checks if there is enough time to implement the new system. It also sees whether the proposed project time table will be able to work or not.

Operational feasibility: determines whether the new system will work with the organisation and meet the goals and objectives. Some people may not want to use new systems and that must be found out in this operational feasibility so planning can be made to solve the problem. It also tries to find out how the end users will be affected and what their reaction will be.

Development approaches Traditional: (UPDIT) It can only go down from understanding the problem to

planning to designing to implementing and then to testing. You can not go back Outsourcing: Making other companies develop part or all of the system Prototyping: this is similar to traditional method, however prototyping is when the

organisation creates prototypes and tests it and re-designs the prototype to make sure it meets the requirements of the project, before it is implemented

Customisation: Changing parts of current existing system to meet the new requirements instead of making a completely new one

Participant development: the people who are operating the system will develop it, giving an advantage of knowing what to develop to meet the requirements and saves time by not going through interviews. However, participants need the skills to develop systems and if they don’t time will be wasted on failures or learning how to develop it.

Agile methods: Used for software development instead of information systems. A small team of developers work on the software usually with a participant to tell them what they want. There is no need for a requirements report.

Requirements report

A requirements report is a document compiled which does the following: Details the time frame : An estimate of the time it takes to complete the

implementation of the new system will be detailed Details the subprojects and the time frame for them Identifies participants: Participants are people who operate or are part of the data

used for the system Identifies relevant information technology: Information technology includes the

software and hardware used in the system Identifies data/information: Data are the input and information is the output Identifies the needs for users: The needs for users are considered to make the new

system more suitable for users so the needs must be identified

Designing Clarifying with users the benefits of the new system. Users are told what benefits will be

produced as a result of implementing the new system, so that the design process can be modified to what they want and also this step is done to make sure time is not wasted with the other steps of the system development cycle if the client didn’t want a system.

Designing the information system for ease of maintenance. The system has to be designed to be able to be used by the participants and the admins/staff of the new system, without much technical knowledge and complications to save time.

Clarifying each of the relevant information processes within the system. This will help make sure there isn’t confusion on the processes during designing.

Detailing the role of the participants, the data and information technology used in the system. This needs to be done to appropriately design the system to suit the participants and be able to use data and information technology.

Refining existing prototypes. If existing prototypes existed, it could be refined to save money and time and use the various aspects of the system that weren’t part of the original idea.

Participant development: When people in the information system develop the systemo Participant designed solutions are better as the participants understand the

requirements much better than external developers and can tweak the system to what suits them. May only perform basic applications as not all participants may be experts in developing new systems.

o Tools such as application packages allow participants to save time to do small jobs and also this is done when the information system personnel are busy with other tasks.

Implementing the system Acquiring information technology and making it operational

o Hardwareo Software

These can be purchased or built (computers and software can be built). If too much time is wasted on getting these items then the implementation stage will be delayed.

Implementation plano Participant training: The plan is used to detail participant training. This ensures

participants learn how to use the new system effectively and is needed during the implementation so participants can know how to use the system before testing, evaluating and maintaining.

o Methods of conversion: Direct conversion: change to a new system immediately discarding the old

one and not using it anymore. All the data from the old system is transferred to the old system and then after that the new system can be used.

Parallel conversion: Both the new and the old systems work at the same time. This allows participants to compare both systems and also if any problems occur and one system is still functional then the operations can still continue.

Phased conversion: Gradually implement the new system. Some parts of the new system are implemented and slowly more and more parts are implemented so that each operation can be fully tested to be working. After one operation has been tested, the next part of the new system is implemented.

Pilot conversion: Have a few group of people test out the new system, while the rest use the old system. If this small group of people like the system then it is changed.

Advantage and disadvantages of different methods of implementation Direct conversion

Direct conversion is when the old system is completely replaced by the new system and the old system is not used anymore.

o Advantages: Quickest and cheapest way to convert, no time is wasted with the old system

o Disadvantages: Participants are not used to the system Parallel conversion

Both systems are used at the same time. After a while though, the old system usage is discontinued.o Advantages: Security (backup: If the new system failed then the old system can still

be used. Also, if staff did not know how to use the newer system, they could be trained whilst using the old system so at least one of them is running)

o Disadvantages: Costly (more resources: Electricity, more staff is needed) Phased conversion

o Advantages: Every part is checked to make sure it works, it is easy to take a step back as not everything is implemented at once

o Disadvantages: May cause confusion because parts of both systems are being used as a whole and the data may not be able to be transferred.

Pilot conversiono Advantages: Old system is still functional, test to see if the participants will like it

and can use ito Disadvantages: Waste of resources as both systems are being used at once. If the

participants do not like it, it will be a waste of time How the system will be tested

o Hardware can be tested with diagnostic software and also trying to do normal operations

o Software can be tested using data which has been structured to test every single possibility

Conversion of data for the new system: Data can be converted in various ways, manual or automatic

Operation manual is needed for reference or help and also to train the participants to use the system. If errors occur, they may be able to diagnose it and even fix it if it is included in the manual and the manual will help make sure things are done correctly

Testing, evaluating and maintaining Testing and evaluating the solution with test data such as

o Volume data: a lot of data is put into the system for processing to see if it can be handled

o Simulated data: Data and processes which would be used in the usual operation of the system are simulated to see whether the system would work properly

o Live data: Real data is used to test and see if it will work once real data is used Checking to see if the original requirements were received Trialling and using the operation manual: The operation manual is given to users or

participants and trialled to determine whether it is suitable or understandable. These questions have to be asked while trialling and using the operation manual: Are the instructions clear? Is the operation manual user friendly?

Reviewing the effect on users of the information system, participants and people within the environment

9.2 Information systems and database

Information systems

Characteristics of an information system

Organisation of data into information: Organisation is the process where data is changed to a suitable format for use by the information system. Data must be organised or structured before it can be stored or analysed by an information system. There are different ways of organising such as sorting, summarising and classifying.

Analysis of information to give knowledge: Analysis of information is the user seeing relevant patterns, trends or changes in the data to gain knowledge. Tools used for analysing include tables, queries and reports.

The different types and purposes of information systems Process transactions: This is the main process in Transaction Processing Systems They

collect, store, modify and retrieve transactions in an organisation. Transactions are any activities or products that are part of the normal operations of an organisation. The main purpose of a TPS is to provide data for other information systems. Batch and real time processing are part of a TPS. - Batch processing: Transaction data is collected and processed at a later time e.g. EFTPOS- Real time processing: Transaction data is collected and processed immediately e.g. ATM

Provide users with information about an organisation: These are also known as Management Information Systems. Data are taken from various sources such as TPS and provides information on the organisation and creates reports on various aspects of the organisation such as sales summaries, budget and production schedules.

Helps decision making: This is usually a decision support system. These systems help people make a decision from the information they provide, models and also from analysis tools.

Manage information used within an organisation: These are Office Automation Systems. They reduce the quantity of work needed to run an office and help improve efficiency and also help complete administrative tasks.

Database information systems

School databases- Participants: Students, teachers, admin/staff, IT support, parents- Data/information: Student attendance, payments- Information technologyHardware: Computer desktop, printer, phones, fax machinesSoftware: Utility- drivers and Antivirus

OS- Windows XP professionalApplication- Microsoft office collectionCommunication: SMS, telephones, fax machines, email

RTA databases- Participants: Drivers, staff, IT support- Data/information: Driver information, Traffic incidents, Fees and fines, registered cars- Information technology: Hardware: Computer, printer, fax machines, phonesSoftware:Utility- drivers and antivirusOS- Windows 7Application- Microsoft office collection, DBMSCommunications: Telephones, email, fax machines, letters

Video store databases- Participants: Customers, staff, IT support- Data/information: Video details, Loans details, Customer details, Movies details- Information technology: Hardware: Computer, printer, fax machines, phonesSoftware:Utility- drivers and antivirusOS- Windows 7Application- Microsoft office collection, DBMSCommunications: Telephones, email, fax machines, letters

Organisation

Non computer methods of organisation Also known as “manual” organising methods For most of history non computer organisation methods have been used Examples of usage today are telephone books, address books, diaries etc. Have some advantages (no power needed) however there are also disadvantages (inflexible,

may be heavy, usually one person can access it at a time)

Computer based methods of organising

Flat-file systems: - All data are organised into a single table- Suitable for very small applications and organisations

Database management system:- Software utility which manages flat file and relational databasesRelational databases:- Uses a series of tables - Manages a lot of data very well- Data are organised in the database involves a schema

- Can use relationships between data in tables- Offer reduced data redundancy

Hypermedia systems:- Hypermedia: Any media (graphic, text) that links you to new information [Hypertext:

Text (only text) which links you to new information]- Limited data processing capabilities

Advantages and disadvantages of computer and non-computer based organising

Tom-tom gps (Computer based organisation)

Street directory (Paper based organisation)

Advantages Directions as you go Faster viewage of map through

searching Save directions Safer than looking at a map while driving Light portable

Advantages cheap no power required no risk of lag and no risk of 0 satellite

collection no risk of technical failure half way

through drivingDisadvantages

Unreliable in underground or indoors/basement parking

Drains car battery power

Disadvantages Cannot be used while driving Is harder to search through Heavy

The logical organisation of flat-file databases

File: A block of data saved onto the computer. It must contain at least one record. Entity: Specific item which is the subject of data collected and processed by an

information system. Sometimes a table is also called an entity. Record: Data describing a single entity (1st definition above) in the database Fields: Data under a column/category in the table Key fields: Contains data which is unique, so data can be easily identified. Every record

uses the same field as a key field. Characters: individual letters, numbers or symbols in each field

The logical organisation of relational databases Relationships A one to one relationship is when each record in the first entity is related to only one record

in the second entity A one to many relationship is when one record in the first entity is related to many records

in the second entity, but those records in the second entity which are related to that one record in the first entity are only related to that one

A many to many relationship is when each record in the first entity is related to may records in the second entity and vice versa

Schema diagram of a car repair

Tables as the implementation of entities consisting of:- Attributes: The columns- Records: Rows

Linking tables using primary and foreign keys- Primary keys: A primary key makes the field under a certain column which it is applied

to have not null values, be a required field and also be unique. Used to usually identify people or things because they have the same names.

- Foreign keys: It is applied to the same category as the primary key in a different table which relates it together.

User views to different purposes- Different people will have different views to different purposes of the information

system depending on what they want to use it for-

Data modelling tools Data dictionaries: These dictionaries describe the data in each attribute. They include :

- Field name: Name of the column (field)- Data type: Kind of data that can be stored in the field such as number, text,

currency, Boolean (yes/no), Date/time- Data format: A way in which data is entered in. E.g. Date can be formatted as dd-

mm-yy or dd-mm-yyyy.- Field size: The length of the field which limits the amount of characters which can be

input into the record for that field.- Description: Specifies the contents of each field- Example: An example of a record in that field

Schematic diagrams that show relationship between entities

- These diagrams show relationships between different entities (tables)- It includes the Primary key, foreign keys, entities, fields in the entities and the type

of relationship (one to one) Normalising data to reduce data redundancy

- Normalisation is the process of organising data into tables using relationships- Reduces data redundancy- Usually produces a lot more tables in the database- Makes sure all data in the database are consistent- First normal form (1NF):

A relation is in 1NF if it has no repeating columns and has different tables for related data and have identifying keys.

- Second normal form (2NF) Must meet 1NF requirements and must include foreign keys

Logical organisation of hypermedia Nodes and links

- Node: A computer that users are lead to after clicking a link- Links: A highlighted item which allows an electronic connection between a person’s

computer to other information Uniform resource locators

- Address of a file or resource on the World Wide Web and allows users to access it- There are no spaces- Can represent the IP Address of the resource as a worded value, because it is easier

to remember- Protocol: ‘http://’ The transfer method to access a resource on the web- Domain name: Address of the computer where the resource is located, can be IP

address as well- File path: It states the folder and finally the name of the file itself e.g.

‘/folder1/web.html’ Metadata such as html tags

- Metadata are data which describe other data- A HTML tag is a metadata because it describes what the data in between the tag and

the closing tag are e.g. <b> is a piece of data which describes the text data within it as bold

Tools for organising hypermedia- Storyboards to represent data using hyperlinks:

These are frames which represent a page in the system, whether it be a database or a web page

There are different types of storyboards.Linear: Simple, sequential path that is set up easily

Hierarchical: Sequential path from the top (home page) and moves down

Nonlinear: There’s no order and users can navigate any way they want

Combination: It is a combination of the above

Software that allows text, graphics and sound to be

hyperlinked- HTML allows text, graphics or sound to be hyperlinked using the following tag: <A

HREF = “ipt.html”> Text/Graphic/Sound </A>- Microsoft word can make hyperlinks

Storage and retrieval

Database management systems- Role of DBMS in handling access to a database: DBMS provides an interface to the

database and allows data to be manipulated and changes the database file. It is software and holds no data of its own. It also lets data be viewed and converted to information. There are also a lot of various functions it can run such as sorting, searching and making forms. Some functions are listed below:• organise data with a data dictionary• showing relationships between entities using schematic diagrams• checking for identifiable errors in data entry• preventing (or trying to) prevent unauthorised access• providing information about the performance of the database.

- Independence of data from the DBMS: The data are different to the DBMS. It is just a file with a lot of data which people can not see without using a DBMS. The DBMS arranges it into information and gives people a view of the data as well as run various functions on it, however it does not contain any data. It is software used to access data while the data are stored in a file.

Direct and sequential access of data:- Direct access:

Fast, immediate file access Data are stored based on a mathematical algorithm Often uses indexes

Index: Table that contains location of data- Sequential access:

Slow Goes through every file in order until the file is found e.g. Video tapes Used on magnetic tapes Goes through data in the order it was stored

On-line and offline storage- On-line storage: Storage where data are always accessible and is fast- Users are under direct control- Hard disks are on-line storage- Offline storage: Storage which uses a device not under the user’s direct control- It is also a storage device which has to be loaded or inserted before it can be used

such as a USB

Centralised and distributed database- Centralised database

Database located and stored at only one site and can be accessed from other computers but it relies on the central computer

- Distributed database Different databases stored on various computers which are kept

synchronised through a network Storage media

- Hard discs- Circular hard platters to store data on and can store a large amount of data. They are placed inside a clean steel casing so it does not get ruined.

- CD-ROMs- Optical discs and can store 670 Mb. It is a plastic disk with metal covering the surface and laser is used to read and write data.

- Cartridge Hard disk in cartridge e.g. floppy disks. Rarely used these days. Hold very little data and small transfer rate.

- Tape- These storage devices are made of plastic strips with magnetic material and it is wound around two reels in a cartridge (cassette tapes) and are rarely used due to slow speed from sequential access.

Media Access Storage AdvantagesHard discs Direct Online Fast, reliable, very high capacityCD-ROMS Direct Offline Cheap, reliable, portableCartridge and tapes

Sequential Offline Cheap

Encryption and decryption- Method of encoding and decoding data- Codes messages and data that can only be decoded with the relevant decryption key

Asymmetric encryption: Needs 2 keys one for encryption and one for decryption. An example of this encryption is a public key and private key encryption.

Symmetric encryption uses the same key for encryption and decryption

Backup and security procedures- Data needs to be kept secure from technical failures and unauthorised access.

Backups should be kept regularly on online and offline storage, in case it gets modified or a technical error or an accident such as flash flooding occurs and breaks the computer with the database. It is very important to secure the data with backups so it can be retrieved easily and a lot of work will not be lost. There are also methods to prevent unauthorised access to protect data loss or privacy invasion. If the data is over a network then more security measures need to take place. Firewalls can be used to check who is trying to access the network and block unauthorised people trying to access it. Passwords can be used, user permission levels can also be used to prevent data misuse or modification from users or staff.

Tools for database storage and retrieval- Extracting information through searching and sorting a database

Searching and sorting: Data can be quickly obtained by searching, which is the process where the DBMS goes through the data in the database and retrieve it. Then the results can be sorted and arranged in an order. Sorting can be done to data in tables or in search/query results.

Query by example (QBE): Users can select criteria for the DBMS to search through, it is easy to use

Structured Query Language (SQL): It is a query language where people write commands for the DBMS to perform on the data.

- SELECT: Extracts data from the database- FROM: Specifies the table where you get the data from- WHERE: Specifies conditions for searching/sorting data- ORDER BY: Sorts the results in either ASCENDING or DESCENDING

order. If DESC is not specified it is ordered by ascending order by default.

Logical operators: These include ‘AND’ & ‘OR’. They are used to narrow or widen the search.

Relational operators: These include ‘>’ ‘<’ ‘inequalities (less than or equal to)’ usually with numerical data and are used to specify what type of results the user/participant wants

Tools for hypermedia search and retrieval- Free text searching: Finding text based information on the currently open webpage

with the internet browser on that page (Firefox: Ctrl+F function)- Search engines: Database of indexed websites which people can search through

Indexing: Getting information about the location of data and storing it in a table. It allows documents to be found with a keyword. Index is built by collecting submissions from owners of new sites and search robots.

Search robot: Software which scans the website by going through links and creates index titles and summaries very quickly.

Metadata: data which describes other data very common Reporting on data found in hypermedia systems

- Data found from a hypermedia system such as a search engine can be presented as list of links which connect to the websites and when it is clicked it leads to the webpage.

Other information processes for database information systems

Displaying: Process of presenting information. It can be in various forms such as printed text report, audio file, or displaying electronically on a computer.

- Report: Formatted and organised presentation of data. DBMS can often create reports, which are displayed and can also be printed. In a report there are static fields, dynamic fields and calculated fields.

Static fields: Items that are not copied from database fields e.g. Report title Dynamic fields: Holds data taken from the database Calculated fields: Data produced from data in the database by calculation

- Constructing different views of a database for different purposesForms allow different views of a database. It can be used to enter/modify and view data in a table from a different perspective. It also is easier to enter data in and looks better than looking at tables. There can be many designs for a form and different sections which people can change such as headings and graphics.

Issues related to information systems and databases

Acknowledgement of data sources: Data that is not collected by a person using it must give acknowledgement the person or organisation which developed the data. Copyright protects every original piece of work from plagiarism to give acknowledgement to the true owner.

Freedom of information act: It was an act which the government made so that Australians can get access to information which the Government or semi-government has.

Privacy principles: People’s privacy need to be considered when handling data in information systems and databases. Many organisations use people’s personal data and store it in their databases. They have to be kept confidential so unauthorised people can not access and misuse it and it helps reassure people strangers are not reading about who they are (e.g. Credit card leaves a trail of where a person’s been to and bought). Since people who are part of the data have no control over how it is used, the government has forced organisations to develop codes of practice to protect privacy.

Quality of data: Quality of data is important otherwise there will be misinformation and errors could occur while processing.

Accuracy of data and reliability of data sources: Accuracy and reliability of data depends on who/what is supplying it and for what reason. Inaccuracies may be caused by mistakes by people or participants who enter data, mismatch of data and out of date information. Inaccuracies can be reduced by doing data validation to check the data.

Access to data, ownership and control of data: Organisations set who can access the data they have, who owns it and also the control of the data. People who submit their information usually have no say in what it will be done, however, they are protect by privacy codes of practice to prevent misuse.

Data matching to cross link data across multiple tables: Similar to Geographical information system.

Current and emerging trends in the organisation, processing, storage and retrieval of data: Storage of data has become faster than ever with the emergence of gradually cheaper SSD’s which are much faster than traditional hard discs. Also USB 3.0 has a transfer rate much faster than USB 2.0. Databases have increased in size by a lot, however storage devices have also increased in size and are quite cheap now.

Data mining is the collective name of the processes which are used to analyse a large amount of data. It tries to identify patterns and trends from the data warehouse, which is a database of cleaned data and the metadata that describes it.

OLAP- Online Analytical Processing. OLAP is a type of system which answers multi-dimensional queries. It does only a low volume of transactions. It can be defined as FASMI, an acronym which describes the characteristics of what OLAP is. FASMI stands for Fast, Analysis, Shared, Multidimensional, and Information.OLTP- Online Transaction Processing. OLTP does a large number of short online transactions.

9.3 Communication systems

Characteristics of a communication system Communication systems are systems which allow users to send and receive data.

It enables people to share and exchange data and information electronically. This is done over a network , such as a LAN.

Communication systems framework

Definitions- Source: Where the message originated from- Transmitter: Piece of hardware which generates or encodes the data onto

the medium creating a signal- Protocol: A set of rules and procedures which must be followed by two

devices to transfer data efficiently and successfully- Medium: Thing which the signal travels through (fibre optic cable)- Switching and routing:- Receiver: Piece of hardware which decodes the signal- Destination: Where the data is being sent and ends up

Functions performed in the communication system in passing messages between source and destination

- Message creation: Message is compiled at the source to prepare for sending. Software application is used to compose the message.

- Organisation of the packets at the interface between source transmitters: The data is organised for transmission by going down each protocol from the Application level to the Transmission level which organises the data packet by wrapping it with its own header and trailer. This is to prepare for transmission. When the message is received the message goes through a reverse process.

- Signal generation by the transmitter: The transmitter encodes the data onto the medium which creates a signal. The transmitter is a piece of physical hardware.

- Transmission: When the signals travel through the medium. The data travels as a wave between the transmitter and receiver.

- Synchronising the exchange: The receiver must use the same timing process as the transmitter, so that the each part of the signal (data) can be detected

- Addressing and routing: Each hardware element the message travels through will read the address (destination of the data) and send it to where it needs to go to (routing). Various transmission level protocols such as Ethernet uses the address of the data being sent and determines the path the message will go through.

- Error detection and correction: When messages go down the various protocols they perform either checksums or CRCs (Cyclic Redundancy Check) values and add them to the header or footers. Then when it goes back up the various protocols the checksum or CRC is performed again to make sure the values equal to the 1st result. Parity check can also be used. Parity bits are added to the data which gets checked by the receiver to make sure all the bits have arrived.

- Security and management: Messages can be encrypted during transmission and also usually have user name and password protection.

Roles of protocol in communication- Handshaking and its importance in a communications link: Handshaking is

when two devices agree on the type of protocol to use whilst transmitting and receiving. Messages are passed between the two devices and a connection is established when the devices agrees on the rules to use while communicating. It is important because otherwise the message would become corrupt if it did not follow the same protocol at both ends.

- Functions performed by protocols at different levelsApplication level

These protocols create messages and organises data so it can be transmitted

Communication control and addressing level Makes sure data or messages are delivered correctly through error

checking and making sure it delivers to the right placeTransmission level

Level where the message or data is physically sent The client server model

- Role of the client and server: The client is a computer on a network which uses the server, which is a computer with large storage space and provides services

- Thin clients and fat clients: Thin client is a computer which relies on servers to provide most of the processes and software functions and does little processing. Power usage of a thin client is less than the power usage of a PC. The thin client is easier to manage as a network administrator. All the data are stored onto the server as well. Disadvantages include bigger capacity server because if it is not big enough, then the server will go down if it is used for high processing tasks by a lot of users. A fat client is a computer which does most of its processing and has most of the application software and is more independent than thin clients and it works when the network is down.

- Example of clients: Web browser: Accesses a webserver and asks for webpages or files and displays them on the computerMail client: Emails are received by the mail client from POP servers and are shown on the computer and they can also send emails

- Examples of servers:Print servers: It controls access to printers for many clients. It receives print requests and queues them so the printer can print the documents in order. They allow cancellation of printing documents and changing priorities of certain documents.Mail servers: SMTP and either POP or IMAP are used on the servers. An email client uses a SMTP application which sends the message to a SMTP server

which then uses either POP or IMAP servers to pass the message to the email client IMAP: Short for Internet Message Access Protocol, a protocol for retrieving e-mail messages. The latest version, IMAP4, is similar to POP3 but supports some additional features. For example, with IMAP4, you can search through your e-mail messages for keywords while the messages are still on mail server. You can then choose which messages to download to your machine.Web servers: provide services to web browsers mainly retrieving and sending web pages. It also allows authenticated clients to edit, upload or delete webpages.

Examples of communication systems- Teleconferencing systems: These systems allow people to have a meeting at

the same time in different locations. There are two types. Audio conferencing where a single telephone call with three or more people at different places occur and they all can talk to and hear each other. Video conferencing is having a face to face meeting where there is a live video of the other person(s) and live audio and video can be sent and received.

- Messaging systemsEmail- allows communication with other email users by sending and receiving electronic messages by computer. It can be sent and received by people with an email address. There is a username followed by @ and the domain name. The message is text and pictures but attachments such as video, music and other files can be added.

- VoicemailIt allows communication with other people by storing and forwarding spoken messages. It is used in mobile phones where the receiver dials the voice mail number and retrieves their voicemail, listening to it. It can also be deleted from the voicemail server or saved locally onto the phone.

- VOIPCalls made over the internet, which can be made to any telephone or it can also be made to computers with VoIP software. If both ends of the call are using VoIP then it’s free.

Other systems dependent on communication technology such as- Ecommerce- Buying and selling goods on the Internet- EFTPOS- Allows people to purchase goods and services with a credit or debit

card- Electronic banking- Allows customers to manage their bank account, but

cheque or cash withdrawals cannot be made

Transmitting and receiving in communication systems

Transmission media- Wired transmission

Data are transferred through wires or cableso Unshielded twisted pair: Cable with two thin insulated copper wires

twisted to form a spiral. This reduces the amount of interference from other cables. It can also be shielded to protect against interference. Its bandwidth is 60kbps

o Advantages: Very cheap due to lack of shield 30-40 cents per metre, easy to install and is more flexible than other cables

o Disadvantages: Low bandwidth speed, not shielded from a lot of interference

o Coaxial cable: A single copper wire surrounded by an insulator, ground shielding and an outer insulator. Its bandwidth is 10Mbps and can be used over a fair distance of less than a few kilometres.

o Advantage: higher bandwidth, it is flexible (can be bent easily), durable due to its outer layer protecting against elements, less loss than UTP, more shielding than UTP

o Disadvantages: High installation costs RG6- $1.50 per metreo Fibre-optic cable: Laser of light to carry data in small glass fibres. It is

very fast, secure and has little errors. Its speed is over 400 Mbps.o Advantage: no interference, fast speed, costly when you have

to splice it (join it or put an end to it)o Disadvantage: A major disadvantage is that it is costly

compared to the other types of wire available and the process of splicing adds more cost to connect to it.

- Wireless transmissionMoves through the air and space and does not need a fixed physical connection with between the source and destination

o Microwave: High frequency radio signal which can be transmitted over long distances. It has been used for decades to transmit voice and data.

o Satellite: Specialised sender and receiver in space which orbits around the Earth. A ground station sends a signal out to the satellite which sends the signal to another ground station

o Radio: Radio waves are used in mobile phones to communicate with the cellular stations

o Infrared: Waves which occur above microwaves but below visible light. It travels in a straight line and can only be used in over short distances. Usually used with a detector, this causes an action to occur such as a TV remote which turns on the TV.

Characteristics of media in terms of speed, capacity, cost, and security Communication protocols

- Application level protocols- HTTP: (Hyper Text Transfer Protocol) Used by a web browser to request a

particular file from a web server- SMTP: (Simple Mail Transfer Protocol) This examines the envelope data of an

email and the SMTP servers relay messages to other servers until it reaches their destination

- SSL- Protocol that uses 2 keys to encrypt data (https)- Communication control and addressing level protocols- TCP: (Transmission control protocol) Requires IP to be operating and ensures

that messages are delivered correctly in the internet. It checks for errors with the checksum method.

- IP: (Internet address): Moves the data packets from sender to receiver. Does not check for errors, but it can reroute (redirect) the message to the most efficient delivery method

- Transmission level protocols- Ethernet: Built into hardware devices used to transmit and receive. It uses

Carrier Sense Multiple Access with Collision Detection to deal with collisions when messages are sent at the same time. When a collision is detected the message will be retransmitted at a later time and if it keeps colliding then the time period in which it waits until it is retransmitted increases

- Token ring: A token which is a special bit pattern travels around the nodes of a local area network. To send a message, the computer adds the message to the token ring. When the message reaches its destination, the token ring will travel around the nodes on the LAN and continue circulating the network and devicesstar

Strategies for error detection and error correction- Parity checking: Checks for errors in data transmission using an additional bit

called the parity bit. It is used to check whether the bits that were sent arrived correctly in 8-bit ASCII data. The parity can either be even or odd, depending on the number of 1’s in the data.

- Checksum: This error detection method is calculated by summing numbers up. The bytes are added up as if they were numbers and then the value is sent along with the message. When it is received a checksum is performed again by the receiver to make sure the values are the same.

- Cyclic redundancy check (CRC) uses a division to check for errors and give a value. The data is divided into already determined lengths and divided by a fixed divisor. The remainder of the calculation is added to the data and the receiver uses the same method to check whether the value of the remainder is the same.

- Error correction is usually done by retransmitting the data. Network topologies: A physical layout of devices in the network

- Star: A central computer (hub, which has a managed switch) with the devices (nodes) in the network connected to it. The central computer sends the messages to the correct device. Each device is connected only to the central computer with wires. If the central computer fails, then the network will fail.

- Advantages: one malfunctioning node doesn't affect the rest of the network, easy to add and remove nodes

- Disadvantage: Expensive to set up, if central computer fails everything else can not communicate

- Bus topology: All devices on the network are connected to a direct line called the bus (the backbone). Messages can only be received by devices if it was intended for them. The devices check the bus for messages and can communicate with other devices. If one node fails then the others can still work and use the network.

- Advantages: Inexpensive to install, easy to add stations, use less cables than other topologies, works well for small networks

- Disadvantages: No longer recommended, backbone breaks whole network down, limited no of devices can be attached, difficult to isolate problems, sharing same cable slows down responses

- Ring topology: Each device is connected in a line arranged as a circle where data and messages travel in one continuous loop around passing each device.

- Hybrid: Uses various network topologies in the system- Wireless networks: There is no physical arrangement. Signals travel through

the air to a device which asks for access to the device it is trying to get to and if it is accepted then the message or data is sent or access is granted

The functions performed by the following hardware components in communication systems

- Hubs and switches: A hub amplifies and retransmits the packets to all attached nodes, while switches determines the receiver of the packets and forwards to the destination nodes only.

- Routers: can communicate with different networks and directs messages through the most efficient method to reach its destination

- Modems: Are used to connect to the local ISPs, which services internet access to users. They provide an interface between modulated analogue waves (for long distance transfer) and digital waves for use by computers

- Bridges and gateways: Bridges link two similar networks, such as LANs. Data packets are forwarded from one network to another and connect to networks that use the same protocol. Gateway links two different types of networks with different protocols, and usually it has to convert the protocols.

- Network Interface Cards: This is expansion board or card which is inserted into a computer that can be connected to a network, allows network to be cabled

- Mobile phones: Send messages or data in 5 data types to other mobile phones, devices such as tablets or computers on the same network or landline phones

- Cables: Provide a direct connection between a node and another device- Wireless access points: WAPS are the central nodes on wireless LANs. They

repeat all the packets they receive- Bluetooth devices: It is a short range signal for transmission between

portable devices. It operates in the 2.4 ghz spectrum. A piconet is a network of Bluetooth devices. Up to 7 devices can join a piconet. One Bluetooth device is the master and the rest connected are known as slaves because they can only send and receive data from the master.

Characteristics of network operating softwareThey include:

o Administration: Manage accounts, check various users, allocate levels of access, assign printers, give file permissions as well

o File management: View, edit, delete, modify files and data, sharing of folders

o Applications: The apps which people can use in the network operating software which is loaded onto the server usually from a client computer. Also there is automated installation systems which can be implemented into the network to automatically install applications on all computers connected to it.

o Security: Backup must be managed, so must security from access from other people as well as checking various files for corruption

Similarities and differences between the internet, intranets and extranets- Intranet: Private network, which usually has connection to the internet and

consists of many LANs joined together. It shares information and computing resources among the employees of the organisation.

- Extranet: Intranet that can be accessed by customers, suppliers or other people outside the organisation. There are FAQs, product information and other information which will not harm the business if made available to people outside the organisation.

- Internet: Global collection of computer networks which exchanges data through various ways such as the World Wide Web, or email. It is not private and if a computer on this network is not protected, it can be easily accessed.

Other information processes in communication systems Collecting: In communication this involves generating the data to be transmitted

- e.g. EFTPOS collects credit or debit card details for electronic banking- e.g. Telephones collects voice mail and also collects and transmit audio data

when making a phone call at the same time Processing: In communication this is the manipulation of data (it is converted into a

form for transmission).The list below states processing in communication devices.- Encoding and decoding analog and digital signals. This is modulation and

demodulation. It is a process used by all modems which provide internet access to computers or devices. Waves travel through the air and gets converted into digital signal so it can be used by computer systems. This is called demodulation. Modulation is where digital information is encoded onto an analog wave by changing various properties of the wave such as amplitude, frequency or phase.

- Formation of data packets:o As data travels down the protocols, a header and a trailer is added to

the data making it become a data packet- Routing: Directing messages in the most efficient path to reach the

destination of the message. It is a process performed by routers. Routers can communicate with networks which use different protocols and different methods and media for communication and send the message through the different networks.

- Encryption and decryption: During transmitting and receiving in communication systems, data needs to be encrypted to make sure any attempt to intercept the data can not be easily done. There are different types of encryption but all require a key. Encryption changes the message into nonsense while transmitting and the person who receives an encrypted message needs a key to decrypt it and make it useful.

- Error checking o Parity bit check: Checks the parity bits in the message to make sure

the data has been sent correctly.o Check sum: A calculation is performed on the number of set bits in

the message and is added to the data. The receiving end also checks it and matches the values of the calculations to make sure they are the same.

o CRC: (cyclic redundancy check) uses a division to check for errors and give a value. The data is divided into already determined lengths and divided by a fixed divisor. The remainder of the calculation is added to the data and the receiver uses the same method to check whether the value of the remainder is the same.

Displaying such as:

- The phone. It displays voice mail, videos received and also text messages on screen. It also displays live while taking or making calls. The data which it can display include text, sound, video, image and numerical data.

- EFTPOS terminal. It displays information on the EFTPOS transaction. It shows the name and price of the item being purchased and also provides a receipt. The main data displayed is text and image (text on the receipt, images on the screen of the EFTPOS system.

Managing communication systems There are network administration tasks to maintain the system such as:

o Adding/removing users: new users can be added and assigned a username and password and accounts of those who left the system or are inactive will be removed

o Assigning users to printers: Printers can be assigned to users or workstations. Usually printers are assigned to workplaces not users because users can log in anywhere and print from the printer, but if it was assigned to a workplace it would be closer to the user

o Giving users access to file rights: Permissions on files or directories can be assigned to different levels or users or specific users or for all users. There are various permissions which allow users to either not be able to access the files, make the file read-only or be able to be modified.

o Installation of software and sharing with users: Installation of software to multiple users in the network can be automatic and saves time.

o Client installation and protocol assignmento Logon and logoff procedures: The administrator manages how people will log

on and off the network. Passwords and usernames will usually be issued so they can access the network.

o Network-based applications: Network based applications are loaded onto the servers. The clients which connect to the network will be able to use the software available on the network without local installation.

Issues related to communication systems Security: If a communication system is not secured messages can be intercepted and

taken or the message may be modified or malicious things such as viruses can be added to it.

o Advantage: more better encryption and protectiono Disadvantage: new security threats such as more fraud, spam and phishing

Globalisation: Communication can be made with people all over the world and although this is good, local businesses can be harmed as buying some items such as phones, laptops from overseas is cheaper than buying the same things in Australia

Changing nature of work: Many people now receive email messages to notify them of changes and workers may not like new technology and prefer the old paper based systems, while some may not know how to use new technology

o Advantage: New opportunities and also work can be easier Interpersonal relationships: A bond/relationship (incl. love, friendship) between two

or more people can be lost from lack of face to face contact.o Positive: You can make a lot of new friends without having to meet them or

make friends from overseaso Negative: The experience gained from face to face contact will be lost

E-Crime: Hacking is known as an e-crime. It is when you commit crimes on the internet, and the crimes are equivalent to real world crimes such as threats, harassment and theft

Legal: Files can be transmitted and communicated over the internet and piracy of files can occur, which is not legal and is associated with e-crime. All of e-crime falls under legal issues. Privacy issues involving messages are also legal issues.

Virtual communities: Social networking websites, online places where a group of people with common traits can communicate with each other and also second life

o Advantages: Education values, money can be made such as creating property in second life

Current and emerging trends in communications Blogs: Online diaries written by people which could be either true of fictional. It can

also be a series of articles written to help people or it could be written entirely just for fun.

Wikis: These are online encyclopaedias on a certain subject or on everything e.g. Wikipedia. They can usually be edited by users.

RSS: A news feed where updates on websites which submit RSS feeds, notify users of updated pages or new pages

Podcasts: Short online audio or videos which can be on any subject Online radio: Music streamed online. Can be a live stream in the internet browser or

from an external program or can be accessed by downloading the radio file and opening it in windows media player.

TV and video on demand: Tv shows and movies made available for streaming or downloads whenever the user requests it to be available

3G technologies for mobile communications: Allows access to internet and better connectivity to phone towers to make phone calls and have better connectivity than previous mobile standards

9.4.4 Multimedia systems

Characteristics of multimedia systems Multimedia systems are information systems that uses a combination of multiple types of

media. There are different types of ways media can be classified. It can be static media, where the content does not change over time or dynamic where the content can change over time. The following are different types of media used by multimedia systems.

o Text and numbers: These are a sequence of characters such as letters of the alphabet, unique symbols and numbers such as 1, 2, 3. It includes ASCII, real numbers and integers. This format is used in books and videos and other multimedia systems. Books can be literally defined as multimedia as it uses text and images and also numbers. Numbers are characters which usually have a format and are generally used in calculations. There can be various ways of representing numbers such as using a pie graph.

o Audio: In multimedia systems, sound is digitised and is made by taking measurements of pitch and volume of the sound. It is used to explain concepts, reinforce selections and provide special effects in the multimedia system. It is commonly in MP3 format as it is a compressed form of audio, using less space than the standard WAV. There is almost no quality difference because the sound humans can’t hear is removed.

o Images: An image is any non text representation. Images on the screen are made of pixels, which are small dots and is the smallest part of the screen which can be controlled by the computer. The number of pixels on the screen is called its resolution. This is given buy the horizontal number of pixels time the vertical number of pixels. Images are either bit-mapped or vector graphics.

Bit-mapped graphics: Treat each pixel on the screen individually and record information about every single pixel. During resizing, they lose detail. They use up a lot of space so it is often found in compressed formats such as GIF and JPEG.

Vector graphics: Images which are represented using math formulas. They can be resized without distortion because everything will be in proportion and it will be very clear. The points of the objects are mapped and the characteristic (position, line width and patterns) of the rest of the image is represented with a math formula. They require less space than bit-mapped graphics and formats are CGM, EPS and WMF.

o Animation: Moving graphics made of still images called frames, which are played quickly. Each frame in an animation is called a cell. Traditional cartoons were drawn on cellulose paper, now most are computer based. They can present information more clearly than images and text because the images are moving and can be visualised more easily. It is usually displayed at 12 fps. Animated GIF and QuickTime are common formats for animation.

o Video: This is a combination of sound and pictures displayed over time. A video is a continuous event where everything is recorded and then broken up into frames, different to animation as animation starts with a single picture and then more is

added to create a moving illusion. Videos are usually at 25 frames per second. More is not allowed because subliminal messaging could occur. Common formats are mkv, mov, mpg, avi, wmv.

o Hyperlinks: These are usually highlighted and blue text in or an image in a multimedia product helping people navigate through it and cross-linking people to other documents, files or websites. It provides interactivity in the multimedia and keeps users interested.

Differences between print and multimediao Different modes of display

Printing is leaving a mark on static material. It output is a hard copy meaning the information is displayed on paper based forms such as books, papers, magazines and posters. Once anything is printed on static material the whole document must be replaced to update it.

Multimedia products on the other hand are displayed using screens and speakers.Screens: Display surface that immediately displays what the computer is doing. It can display text, number, image, animation and the visual part of the video. The resolution and size of the screen can affect the quality of the multimedia product. Speakers: Displays sound. They are usually built into laptops, however for desktop computers external speakers must be connected to the sound port.

o Interactivity and involvement of participants in multimedia systemsPrint provides less interactivity between the product and the user whereas multimedia systems have wider interactivity possibilities. Interactivity is when the user is allowed to choose the order and content of information. For example the Internet is an interactive multimedia system using hyperlinks to move through different pages. Multimedia systems accept input from mice, touch screens or keyboard and do an action in response to this input.

o Ease of distributionPrint systems take longer to prepare and distribute than multimedia systems because there is time needed for the physical transportation of the item. However the systems which produce printed items can be easy to use or automatic, meaning there is less input from the distributor and there are no platform issues, meaning specialised equipment is not needed by the receiver.

Multimedia systems can be quickly distributed over the internet however special equipment may be needed, such as specific hardware and software.

o Authority of documentIt is easier to determine print product’s creator, date published and the owner, but in multimedia products it is much harder and less reliable.

Demands placed on hardware by multimedia systemso Primary and secondary storage requirements: Many multimedia systems require

large amounts of storage to produce a better quality product. Primary and secondary storage requirements are determined by the following:

Bit depth and a representation of colour data Bit depth is the number of bits needed to store information about a pixel. One or more bits must be stored about each pixel on the screen. Video and animations are made up of bits on each frame and the audio data with it.

Sampling rates for audio dataBecause audio is analog data, an ADC is needed to convert it into digital data. Samples or parts of the audio wave are recorded as bits, and the number of samples taken is the sampling rate, usually measured in seconds. During sampling, the amplitude of the wave is converted to a number.

Sampling size: Number of bits per sampleo Processing as a result of:

Video data and frame ratesFor video data, a lot of processing is required as it is made up of both analog audio and image data, which needs to be converted into digital data. In video cameras, there is a video capture card, which converts analog signals into digital signals. Editing must also be done to make the video better for presentation or suit the creator’s purpose and make it a multimedia product. Editing can involve adding text, audio or images to the video. This places high demands on hardware systems as videos are usually large so more processing needs to be done in order to be able to edit it. The frame rate is how often the image changes usually measured in fps.

Image processing (commonly found in animations) Morphing: Morphing is smoothly changing one image to another.

First there is just one image, and then the second image is slowly incorporated into the first image, until the second image completely replaces the first image.

Warping: Distorting part of an image. It divides the image into things which can be manipulated.

Animation processing Tweening: Generation of in-between scenes by animation software.

This means the software automatically fills in what it believes will occur between one scene and the other.

Display devices as a result of: Pixels and resolution: Pixels are tiny dots of the screen which

produce colour. Display device resolution (meaning the number of pixels on the screen horizontally and vertically) must be adequate so the image does not look bad and pixelated

The variety of fields of expertise required in the development of multimedia applications. There are several roles which people need to undertake to help create a multimedia product and they include:

o Content providers: People who provide the media for the multimedia product. This includes images, text, audio, video and graphics and sketches. They are experienced in the type of media they provide, but do not necessarily have good technical skills.

o System designers: System designers are those who design the system and plans and organises the hardware and software to be used. They work out the requirements of a system and find a feasible solution.

o Project managers: Manages the product through scheduling, supervising all the components and making sure everything goes well and on time.

o Those skilled in collection and editing of each of the media types: These people are specialists in what type of media they collect and edit and are needed to get the best possible multimedia product and help create an application which works.

o Those skilled in design and layout: These people make sure that the multimedia product is easy to use, keeping things clear and simple. Having expertise is design and layout will allow the client’s needs to be met.

o Those with technical skills to support the use of information technology being used: These people can help solved technical problems and also ensure that the technology is appropriate for the client. Those with technical skills are also people who work on the parts of the multimedia product, supporting the back end. Examples could be somebody responsible for backups or scripting.

Examples of multimedia systems The major areas of multimedia use, including:

o Education and training: Multimedia systems are great for learning and educating people because it maintains their interest through interactivity. It allows greater understanding of items through a graphical or audio representation of the item. It also allows training to occur at convenient times (e.g. video tutorials can be opened and listened to whenever). It is also a cost effective method of training. Examples include sports performance monitoring, help files and tutorials.

An example of a multimedia system used for education and training is CBT (Computer based training). A person uses CBT at his own pace. Different types of media are used and provide opportunity for the user to go over things in the CBT. Typing tutor is an example of this CBT and helps train people to type and assesses their level of typing, before teaching more advanced techniques.

Advantages/disadvantages over traditional form of education and training: Costs more More interesting due to interactivity & different media types Can be carried out with large numbers

o Leisure and entertainment: These systems are often referred to as computer games. Different types of media are used, although there is minimal text and the interactivity may vary depending on what type of game it is. The response of the user determines what occurs in the game and the sequence of actions may be short or long depending on the game designer.

o Information provision such as information kiosk: Information can be provided with multimedia systems, such as with a multimedia encyclopaedia. There are a variety of

ways information can be displayed making it easier to understand the information and the interactivity allow greater control of the information. Information kiosks are machines with a touch screen that allow people to find information about an organisation or service. The user chooses the information to be displayed and these are commonly found in places like shopping centres, providing information to location of shops, services and description of items.

o Virtual reality and simulations such as a flight simulator: Virtual reality is using computer modelling and simulation to create a fake environment in which the user interacts with. These usually simulate real world things using realistic modelling and graphics to provide a close to real experience. Flight simulators train pilots and have external effects such as weather conditions, to test how well pilots can fly. It is very expensive as good hardware is needed with good graphics and the scenarios need to be carefully designed to be as realistic as possible. Flight simulators also take up a lot of space and involve complex systems, adding to the cost, but it is cheaper and safer than risking people’s lives and real airplanes. Advantage is also immediate feedback and can be used to recreate real events and investigate what happened. Different environments can also be experienced by pilots in flight simulators, such as flying on ice. Other negatives include: it doesn’t fully represent reality creating an over reliance on artificial environments, costly as well.

o Combined areas such as educational games: Different areas can be combined to produce a better, more useful product. An example is educational games, combining learning with entertainment, further reinforcing concepts.

Advantages: Disadvantages:

Advances in technology which are influencing multimedia development:o Increased storage capacity allowing multimedia products to be stored at high

resolutions: With cheaper, bigger hard drives and USBs, there is now room to store high resolution images. Better quality images can now be viewed allow greater appreciation of multimedia products. Multimedia products can have graphics and videos at great quality due to increased storage space, allowing for more details for each pixel to be recorded. Movie servers can also be set up.

o Improved bandwidth allowing transmission of higher quality multimedia: Compression is not needed as much due to better bandwidth allowing faster data travel speeds, meaning greater quality multimedia can be enjoyed much faster than they could be. New possibilities can occur such as streaming videos onto tv over the internet.

o Improved resolution of capturing devices: Allows high quality media to be recordedo Increases in processing powers of CPUs: Satisfies demands of a higher work rateo Improved resolution of displays: Quality of the output is important for userso New codecs for handling of media while improving quality: Speeds transmission and

reduce storage requirements and be pleasing for the user to view Codecs: Computer software that both shrinks multimedia file size

(compression), and makes them playable on your computer (decompression). e.g. mp3, divx, xvid

Displaying in multimedia systems Hardware for creating and displaying multimedia

o CRT (cathode ray tubes). They are bulky devices which consist of three electron guns which fire at a screen that has phosphor dots producing glowing colours. TO create an image many phosphor dots are hit simultaneously. Colour images are created by the electron guns firing a primary colour such as red, green and blue. Most CRT displays use a raster scan. It fires the electron stream is a series of zigzag lines maintaining the image on the screen, because the glow only lasts for a few seconds. This is called refreshing.

o LCD displays (Liquid Crystal Display) are flat screened. A liquid crystal layer is a crystal layer between two polarised screens. When a current is applied at particular points light passes through the liquid crystal. They take up little space and are as good as CRT quality. Also use less power and emit less radiation than CRTs. Transistors are needed to produce colour.

o Plasma displays: These displays have pixels on the screen made up of red, green and blue. Charged electrodes react with gas in the screen, becoming plasma, producing UV light, which then reacts with the red, green and blue phosphor on the screen in each pixel producing light.

o Touch screens: These are screens which sense people touching the screen by detecting the touch of the user’s finger as it interrupts infrared light beams shining on the screen.

o Digital projection devices: These are devices which can project images onto other medium. These include data projectors.

o Speakers and sound systems: Digital signals are converted into analog sound waves for transmission. Sound is produced electromagnetically. A coil of wire is attached to a cone or diaphragm. The coil is wrapped around a magnet, becoming magnetised when any electrical signal passes through it. As it is being magnetised, the coil moves, moving the cone or diaphragm at the same time. As the cone or diaphragm vibrates, the air around it vibrates causing sound.

o CD, DVD and Video players: CD, DVD and Videos are devices with media such as audio, image and video stored on them. The players for these media storage devices usually are connected to a screen and read the media on the CDs, DVDs or Videos and sends signals to the screen and speakers.

o Heads-up displays: These are devices worn on the head which can display image, video, text, sound and animation. It was originally designed for virtual reality.

o Headsets: Headsets are devices worn on the head which allows people to listen and speak, as it has speakers and a microphone. It is usually connected to computers or phones as well as other devices.

Software for creating and displaying multimedia, including:o Presentation software: This is used to display multimedia professionally to a group

of people and helps create a more effective presentation. Presentations are made up of slides, which are defined as an individual screen or page of the presentation. Links can be easily made between slides with presentation software and allows for an automatic presentation. Examples of presentation software include Prezi and

Microsoft Powerpoint. They create documents which are used in a presentation such as audience handouts and speaker’s notes.

o Software for video processing: Videos can be edited by this software and also be converted to suitable formats with a range of codecs so it can be displayed on various devices. Clips from different sources can be edited and then merged to form a movie. Images, text and numbers can also be added. It also allows storage on various storage media, such as CDs and DVDs. This software also opens and plays videos.

o Authoring software: Creates a multimedia product by combining various types of media and stores it onto CD, DVD or tape. It allows users to create interactivity in their multimedia product by using a scripting language which assigns relationships and actions they will perform.

o Animation software: Takes images and displays them quickly to give a sense of movement. There are cell-based and path based animations. This software allows control of various layers of a frame to control movement of the image. It controls the frame rate and sizes. Tweening and morphing is also used.

o Web browsers and HTML editors: Web browsers display web documents as do some HTML editors. It also displays web pages in other languages such as Javascript, PHP and with additional plugins also Flash and other formats. Web browsers configure the security level of a webpage. They also allow download of files. HTML editors create web pages using HTML. HTML editors allow various elements and media to be added into a webpage such as hyperlinks, videos and audio. Some HTML editors are WYSIWYG, such as Dreamweaver CS5.

Other information processes in multimedia systems Processing:

o The integration of text and/or number, audio, image and/or video: Multimedia systems perform various processes which combine different types of media together to create a multimedia product.

o Compression and decompression of audio, video and images: Since multimedia products often result in large file sizes, compression is needed to reduce the number of bits needed to represent the information. Compressed file formats are very common in multimedia systems and these include JPEG and GIF. A codec is an algorithm used to encode and decode many types of data. Codecs are used for audio and video. They convert analog signals (audio and video) into compressed files.

o Hypermedia- the linking of different media to another: Multimedia systems have the ability to link different together to provide new information and also create interactivity for users to keep them interested.

Organising presentations using different storyboard layouts such as:o Linear: A simple sequential path showing movement in one direction (usually in one

line)o Hierarchical layout: A top down design starting from the beginning then going

through various pathso Non-linear: No structure with frames and just arrows

o Combination: Uses a mix of these types of layouts

Storing and retrieving:o The different file formats used to store different types of data:

Different file formats are used depending of the quality of the data and the application software used to create the data.

Images Jpeg (Joint photographic experts group): Stores bitmapped images.

Can have a high compression ratio of 100:1. Uses lossy compression so quality and data is lost. Can use 16.7 million colours.

GIF (Graphics Interchange Format): Stores bitmapped images. Use lossless compression. Can only use 8 bit colour (256 colours). Has a compression ratio of 2:1.

PNG (Portable Network Graphics): Uses alpha channels, gamma correction and two dimensional interlacing.

BMP : Videos and animation

MPEG (Motion Picture Expert Group): Standard format for compression of video. They have a high compression ratio due to use of lossy compression and only storing changes from one frame to another. MPEG-1 has a lower resolution than MPEG 2.

QuickTime: Video and animation format made by Apple and built into Macintosh. There is also a windows version.

AVI: MWV:

Audio

MP3: (MPEG Audio Layer 3) has a compression ratio of 11:1. It is a format to compress audio sound and can compress CD-quality sound. It removes wavelengths of sound which humans cannot hear.

Wav: Can store 8 or 16 bit sound. They do not have much compression and have a large file size.

WMA: MIDI: (Musical Instrument Digital Interface) It is a connection with

the computer and a MIDI musical instrument. When the music is played the computer stores information on the notes and not the details of the soundwave, requiring less storage.

Animations SWF:

o Compression/Decompression: Compression is done to minimise transfer times, bandwidth and storage requirements by reducing the number of bits required to represent the information. It is done with codecs, which is an algorithm. When the compressed media is viewed it has to be decompressed. The amount a file is compressed by is found using a compression ratio, e.g. 2:1. There are two types of compression:

Lossless compression: This compression allows the full file to be recovered, when decompressing, after it has been compressed. It does this by finding repeating data and replacing it with something which is smaller in size. It is mainly used on text files such as word documents.

Lossy compression: This compression results in a smaller file size but sacrifices some quality. It is mainly used on images, videos and audio. Redundant data is eliminated and also data which humans cannot sense such as different frequencies of sound are eliminated. This provides very high compression ratios. Some formats of this include: JPEG, MP3.

Collecting: When data are collected for multimedia products, they can either come from a digital source

or be digitised from an audio format.o Text and numbers in digital format: Text and numbers can come digitally from

keyboards.o Audio, video and images in analog format: Digital cameras and video recorders are

devices which capture video and images. Microphones are devices which capture audio only. These devices capture analog data and then save it as digital data.

o Methods of digitising analog data: Flatbed scanners: Documents are scanned and then saved as images. OCR

software then scans the document and finds text and numbers converting it to a digital form allowing editing of the data such as copying the text.

Speech recognition software: Audio data is converted by the software and changed into text and numbers. It can be collected from the web or other places where you get audio files or from a microphone.

Sound cards: Sound cards convert analog signals into digital data which can be understood by the computer. They are found inside microphones and video cameras.

Video capture card or software: These are pieces of hardware which can convert video and image analog data into digital formats. Video capture cards interpret each frame of the video as a bitmapped images. They also compress the video clip. Video capture cards Software can used to create animations and images.

Issues related to multimedia systems Copyright: the acknowledgement of source data and the ease with which data can be

modified: Work of other people’s is protected by copyright meaning it can not be used without the creator’s permission. Students who use multimedia products for their work have to properly cite the author and acknowledge where it came from. There is a minimum amount of information which must be stated to acknowledge the place where the product came from. Multimedia products can be easily modified, but the product is still covered by copyright and can not be done without the creator’s permission.

Appropriate use of the Internet and the widespread application of new developments: Privacy is an important issue and when using internet it must be considered. New developments such as live video streaming can cause problems such as streaming people from the street and placing private videos can occur. Multimedia products can also be shared easily on the internet, and illegal products can be transferred, however this also allows for better sharing of legal files which can help people such as information and free tutorials.

The merging of radio, television, communications and the internet with the increase and improvements in digitisation: The merging of technology is occurring very quickly. Everything is becoming dependant on another and people have to buy lots of different things using money. Since computers have many new capabilities, it can replace the need for other technologies such as radio and television and everything can be done on just one device. Improvements in digitisation can save costs as well as make multimedia usage become extensive. Merging of different technologies are also changing the nature of work such as usage of smartphones and tablets.

The integrity of the original source of data in educational and other multimedia systems: Data integrity is the reliability of the data. If the data integrity of a multimedia product is bad then usage in education systems will cause false information to be distributed. Data can be easily obtained from the internet, however, the data may not be reliable and accurate. To make sure it is reliable, data can be taken from various websites and cross check them.

Current and emerging trends in multimedia systems:o Virtual worlds: Virtual worlds are being increasingly used due to advances in

technology. There are many purposes including entertainment, education and scientific and social research.

9.4.3 Automated manufacturing systems

Characteristics of automated manufacturing system Automated manufacturing systems as information systems involved in production, by

inventory tracking, record keeping, production scheduling and actual production:

Automation refers to systems which automatically do various industrial processes, which were once done by humans. Manufacturing is the process of producing a product which meets the requirements of the intended owner of the products. The information technology in automated manufacturing systems has different uses.

o Inventory tracking: This is when the location of products and parts are recorded. Staffs are also tracked and can be traced back to their shifts. This data can also be analysed to check demand times. Allows products to be ordered when they are needed while also maximising production times.

o Record keeping: Storing information on the employees, such as how well they worked and what they did

o Production scheduling: Each part of the production is scheduledo Actual production: These systems also manufacture the product and follows the

schedule The direct users of this system as:

o Supervisors overseeing operation: Supervisors use the information from automated manufacturing systems to determine whether an operation is running smoothly or not. They also use the information to make sure everything is running on schedule. Usually they depend on the system heavily for information, such as in an automated warehouse because there may be no lighting to save money, so the supervisors can’t see.

o People whose task is dependent on the system for information: These people are direct users who need the information from the system to do what they need. Examples of information needed from the AMS could be:

Numbers of parts needed for a product Number of employees and skills needed to produce the product Cost of parts Cost of production Sources of component parts Prediction of market need Number of finished products in stock

The ability of these systems to collect data from the environment through a wide range of sensors, process this data into information and use this information to complete a physical task: Data collection from the environment for AMS involves using sensors. A sensor is an input device that measures data from the environment, getting information such as: Temperature, pressure, motion and light. Data is then processed with a microprocessor and a controller. A controller converts the data into a form suitable for use by the system. Actuators do the physical task by getting signals from the controller and carrying out a mechanical action. Usually when a product is manufactured, it moves from one place to another where a different task is performed on it.

Infrared sensors vs. microwave sensors: Microwave sensors use microwaves and send it out. The microwaves bounce back and a change in the waves is detected if movement occurs.Photoelectric: Beam is always being sent and always being received on the other end. If interrupted it sends a signal to the sensor and then the processor.

The use of microprocessors in these systems as a controller: Microprocessors allow various processes such as analysis of data to occur in AMS.

Block diagrams as a tool for describing the interactions between information technology items within these systems: These are diagrams which represent systems. Circles represent Input or Output, rectangle represents a systems and circle with a line through the middle represents the output of one system which is also the input of another system

These diagrams can also be refined, meaning each part is represented as subsystems and is in the systems rectangle.

Examples of automated manufacturing systems specific examples, including:

o Assembly line production such as the car industry: An assembly line is a series of workstations where each part of the product is worked on and processed, meaning

the product is created as it passes through each workstation, connected by a transfer system which allows them to be moved. The production needs to co-ordinated using programmable logic co-ordinators (PLCs). They are used to capture data, control timing and control actuator.

Assembly lines are used in the car industry. There are over 5000 parts in a car. Assembly line production allows good quality control and reduces the cost of production. The AMS system also records information and data, such as parts ordered from other manufacturers and also data on the employees in areas such as accounting and management. Information about the actual production also is recorded such as the time required making the car, machine maintenance and faults in production.

o Materials and production scheduling: System where production of materials are scheduled automatically by computers. This is vital so production can continue without major delays.

o Automated warehouses: These systems automatically manage storage of items in warehouses. The location of items are tracked for the following reasons:

Knowing when to re-order a part Monitoring the daily or weekly use of a part

The location of items is stored using a barcode. When the barcode is scanned and the information is stored in a database, you can find out information on the product and where it is located. Automated warehouses use automatic machines for unloading and loading a product. These machines are controlled by a central computer, which has access to the database. The computer can also track products over many different warehouses.

o CAD/CAM such as: computing numerical control (CNC) systems: CAD is Computer Aided Design system. Developers plan out their product on the computer instead of on a drawing board. The model created is stored on a database. The CAD software allows analysis of the model and makes changes depending on the results of the model. After everything has been designed by the person the software makes detailed drawings required to make the product.CAM is computer aided manufacturing. It is a group of manufacturing tools which are operated by computer systems. Actions of various equipment are controlled and data are collected and analysed, with the results being sent to management.CAD/CAM can work together and is used in industries. Everything related to the manufacture of the product is automatic, including the design and the manufacture itself.

o rapid prototyping: Rapid prototyping is using various techniques to quickly obtain a model prototype of part of or a whole product using CAD data.

How it works: A CAD model is converted into STL file format The machine creates the items by slicing each layer of the model Everything is cleaned

o Mail sorting: Mail sorting is the process used to deliver letters. Letters are collected, sorted and then delivered to the intended address. Mail used to be sorted by hand,

but now there are automated sorting machines. These machines use OCR machines. An example of this machine includes Electrovision EV-40. It is used in high-volume outbound and incoming mail applications. It is a software which is installed into the automated mail sorting machines. It scans the letter and finds the four lines of address on machine printed mail. This is converted into a barcode and is encoded onto the letter. Barcode mail increases savings and efficiency.

reasons for automation, including: o repetitive tasks : Repeated actions are done accurately as opposed to humans, due

to its automation. Humans can get bored doing repetitive tasks, decreasing productive and increasing errors.

o faster decision-making: Can analyse products faster than humans and process data more better. Control systems can respond quickly to changes so the production process occurs quickly and is continuously running.

o safety: can be used to identify dangers. People can work with increased safety because the dangers will be identified so they can be avoided and fixed through use of sensors. Also as some machinery replaces workers in dangerous conditions, the risk is avoided in the first place.

o cost reduction: Can run for a long time with low costs as opposed to humans and their benefits (holiday and sick leave). There is also better control over waste and usage of materials by the machines, meaning things are not wasted.

o customisation: Products can be made to a customer’s specificationso quality control: Quality over products can be maintained at an equal level due to

automation. As machines do not have emotions they are more predictable than humans and are safer in terms of keeping the products the same quality, as humans may purposefully break items or modify them. Products will almost be the exact same and quality control is achieved through a lower tolerance range making sure low quality products are not released to the public.

o precision and acceptable tolerance range: Machines usually have a lower tolerance range allowing for better products released to the public

o Productivity gains: More products are produced cheaper, quicker and better than humans producing it leading to productivity gains. Machines can work for longer, better and cheaper and do not need the same requirements that humans do, such as holiday and sick leave, lunch and toilet breaks. They also do not get sick so can continuously work, although machine errors can occur.

o gains through simulating and modelling, such as: Automated structural calculations: The CAD software can create a virtual

model which can be used in simulations. A model can be created by the system automatically and can be changed by putting it through simulation, making automatic structural calculations to fit the criteria. This allows knowledge to be gained and is cheaper than creating a real model and building components to simulate an environment. It is also much faster than creating a real life environment, instead of running models through a computer simulation.

Automated ordering of components: Parts can be ordered from manufacturers automatically, by using a model and find out the parts.

Collecting in automated manufacturing systems systems that collect data and information from participants via computer aided design

(CAD) software and directly link this to the rest of the system through computer aided manufacture (CAM): There is an interactive page on the CAD software which participants can use to create the data and design the product. Data are stored in a database, containing information on product specifications. The CAD software allows further manipulation of the design such as:

o Image manipulation: add, delete and editing imageso Transformations: Changing the image, such as rotating and scaling imageso File management: Create, merge and delete files

CAD designed data are used in CAM to create the product automatically. identification of the data to be collected and the most appropriate input device: Sensors

are devices which measure data from the environment. Analog data are collected and they convert one physical quantity or another, either by creating voltage or generate a potential difference. To get a good sensor it needs to be accurate, have high resolution, repeatability, range and a dynamic response.

the physical operation and scientific principle(s) underlying sensors used to collect data, including:

o Temperature: These sensors measure the temperature of the air, fluid or any object. In industry, temperature control is required to manufacture the products. If an item gets overheated then it will melt and cause deformations. Temperature is detected using the resistance of a conductor. With changing temperature comes changing voltages. There are three main types of temperature sensors:

Resistance thermometers: A metallic conductor is used. As the temperature changes, resistance to the electrical current changes. It is either coiled or deposited as a thin film on a material called substrate. Used for temperatures between 200-800 degrees Celsius

Thermocouples: Temperature is measured using two different metals that are in electrical contact. Voltage is produced proportional to their temperature differences. The point where the two metals meet is called the thermo junction. There are two junctions, one which is used as a reference temperature and the other which measures the temperature of the metal that is used to make contact with the item being measured.

Thermistor: Works like a resistance thermometer, however, the resistance in the semiconductor is rapid, leading to faster more accurate results.

o Pressure: These devices measure the amount of power coming from a source. A pressure gauge is a sensor which senses pressure in a pipe or container.

The gauge is a curved tube which is connected to the liquid or gas being measured, and the pressure forces the gauge to change shape, into less bent or a full straight line. This movement is turned into a voltage using a resistor called potentiometer. The resistor also has a current going through it and

the difference between the voltages can be detected as the resistance changes. The voltage is then used to register the pressure.

A diaphragm is usually a small piece of material inside a container, with one side in contact with normal air and the other side in contact with the object being measured. This causes the diaphragm to move and this gets converted into voltages and is passed to a computer.

o Motion: Motion sensors detect how far an object has moved from its initial position. This is done by using electromagnetic induction to see how fast and far the metal has moved in a magnetic field. The device is an armature with fixed magnets around it like an electric motor. Rotation of the armature produces a current in the windings and a voltage proportional to the rate at which the conductor is being rotated.

o Flow: These sensors detect movement of liquids and gasses. Often used to measure fluids in pipes and drains. There are different types of flow sensors. A simple one is a small paddle wheel being used and the fluid causing this wheel to turn. The speed of the rotation measures the flow of the fluid. This wheel is attached to a tachometer and creates a proportional voltage allowing flow to be measured. Another flow sensor is one which uses ultrasonic signals to detect a frequency change due to moving fluids and this is converted into a voltage.

o Light: These sensors detect a change in light and are used to test for imperfections, such as dents, in products Light sensors are also used on robots so they can detect their surroundings and are used to control robots. With complex optical light sensors in robots come two main problems:

The amount of data that has to be transferred involves high frequencies, resulting in an increased number of bits required to travel per second so the bandwidth must be high.

A lot of processing must be done on the data to quickly analyse it and determine whether each pixel is an object or not.

Other simpler light sensors include a barcode reader which only detects between black and white.- A photodiode is a device which detects any light which falls onto its surface and produces a voltage proportional to the light which falls on its surface. It is used in light beam switches. A light is shone onto the diode and whenever the beam is interrupted the voltage of the diode falls. It is used to detect whether an object is present or not.- CCDs are also sensors. It is made up of a grid of photosensitive elements. As light falls on the grid electric charge is generated. CCD devices are used as cameras for use on robots and in industry. Advantages of CCD cameras include:

- low voltages (safe) and low power requirements (cheap)- accurate, moving objects are not blurred

where are ac motors used/ what characteristics/ why they not used in home appliances or r they

o AC motors are used as a power source for automated equipment because it can be operated easily by connecting motors directly to an AC power supply.AC motors work when a current is passed through the coil twisting it. It needs to run at a sine

wave to run smoothly. There is energy wasted due to the high current which needs to pass through the motor to power it well and this can cause cost problems as well as shorten the lifetime of the motor, which is why they are rare in household appliance as it will waste more money to people and it is dangerous because sparks are also produced from AC motors.

the integration of sensors into manufacturing machinery to automate processing, such as:o robotic arms: Automated robot arms have a variety of sensors. This helps the robot

to determine what to do and where certain products are. Sensors allow the robot to move on its own and determine its own path without having to follow pre-programmed positions so it can still work if an object is slightly misplaced.

o conveyor belts: Photodiode can be used to detect whether a part has moved onto another part of the conveyor belt by detecting its presence. The process that is needed to work on that part on the conveyor belt is then done and the conveyor belt moves on.

barcode readers, radio frequency identifiers tags (RFID) and inventory tracking and production: Barcode readers are input devices which scan barcodes and allow it to be read by a computer. Barcodes are black and white bars with different widths. When scanned, the barcode reader changes the patterns into characters sends them to a computer for further processing. The barcode contains information about the product or part. This information can be used to track the number of products and parts there are to manufacture the product. An inventory is the amount of products and parts there are in stock. It is important to have an adequate inventory to allow manufacturing of products to keep running, maintaining profits.

o RFID (Radio frequency identifier tags): These are like barcodes however are read wirelessly within the field of these tag readers. It does not need line of sight to read this so is faster than scanning barcodes and can also hold more information. The tags are attached to or incorporated into an item which sends out radio waves and can be identified due to their unique radio frequency.

Characteristicso Active: These are active tags and use batteries although they can be connected

to an external source. it has a long range and can be read at 100 feet or more. However these are quite large and are quite expensive, $20 or more. Used in etoll collection. It has the highest data bandwidth and can initiate communications. Maintenance can cost more for active tags than passive tags especially when battery is replaced. However due to usage of the battery it can include extra things such as sensors for additional data.Passive: Passive tags are tags which do not contain a battery and gets the power from the reader. When the radio waves pass through the tag, a magnetic field is created from the coil in the tag and electricity is generated. This is used by the tag. This tag then sends information encoded onto the tag’s memory. It can only be read at very short distances. They have a longer life than active tags due to no usage of the battery (20 years +) and are smaller than active tags. It is cheaper to manufacture.

the analog nature of the data collected by the sensors and its conversion to digital for use in the system: Data collected by sensors are analog because in the real world everything is

analog. To be used by a system it needs to be converted into a digital signal to allow for processes such as analysis. ADC (Analog to Digital Convertors) and DAC are used to convert between the two types of data.

o ADCs receive analog data which include voltages and is converted into digital data which are made of bits

Damping as the process that modifies the signal to the output device based on the input signal: Process of changing the output of an actuator so it is stable by the controller. The input from sensor is processed by the controller and changes the actuator’s action. It is usually automated through a feedback system where sensors keep collecting information from the environment changing the output.

types of damping, including:o Underdamping – a quick response to change leading to rapid fluctuations:

Underdamping is when the actuator reacts quickly to a change in the environment detected by the sensors and controllers but takes a short while to change to a stable level. While it is getting to a stable level fluctuations in the output occur.

o Overdamping – a slow response to change without fluctuations: Overdamping is where the actuator takes a long time to react to a change and takes a long time to reach a stable output level.

o Critical damping – a quick response to change and quick return to stability: This is used in AMS systems which require a fast response to changes and needs to return to stability quickly. The fluctuations are less than underdamped systems and become stable quickly.

other information processes in manufacturing systems • processing: In manufacturing systems processing is used on data to be converted into a form suitable for transmission. A controller and a microprocessor work together to convert data and perform tasks on it.– the trend to mass-production while meeting the needs of individuals : Mass production is manufacturing products in large quantities. There are many principles which need to be taken into consideration when mass producing items including:

Standardisation of parts Machines which require little human input and have a high output rate Planning Division of tasks

Mass production have led to cheaper products due to the cost effectiveness of the production and also the products are more similar to each other, or the exact replicas. There are many advantages

of mass production such as easier inspection of products as they should all be the same and quality can be controlled with mass production However, mass production is not flexible because many of the products are continually being manufactured and if there needs to be a variation then the future products are affected. Also due to the standardisation of parts for the machines making the products, new machines may need to be bought or the machines must be modified wasting money and reducing efficiency due to install/modification time.

– the different types of systems and the features of each type of system, the types of tasks they perform and the scheduling of these tasks: - Continuous: These systems are designed for manufacturing products whenever needed. There are specific, scheduled times for maintenance, but other than that product manufacturing is almost continuous. It is often used for products needed in bulk and examples of products manufactured by continuous systems are chemicals, food and metal. It is very hard to modify to make new products. it is usually continuous production due to demand and is almost always used to make one product only. Another e.g. is iron ore.

Advantages:o Cheap to build because usually it is only for one producto Economical to runo It is easy to run for human operatorso Fast production rate

Disadvantages: o Hard and expensive to modify, but for cars that are the same model, there

can be different coloured products- batch: A batch system is a system which produced a set number of goods at one time. Usually each batch run is for similar, but slightly different products. Some of the same manufacturing equipment is used, but new ones can also be added. It can be reprogrammed and changed whenever a different product is required for batch production. Batch systems can be completely automated however humans need to have more IT skills to reprogram the controller to produce new products. Examples include fruit tins for fruits which are good for different seasons.

Advantages:o Suitable for large production runs of similar products

Disadvantages:o Need humans to have moderate computing skills

- discrete: These systems are used to produce items which are needed in small quantities. The whole system is used for just the production of one product. Items can be customised and this requires the participants/operators to be IT professionals who can program and monitor the manufacturing process in the system. Generally takes a long time to build. It is used to usually produce expensive/high value items such as a jet, satellites and oil rig carriers.

Advantages:o Flexible: Different products can be easily made

Disadvantages:o Expensive to makeo Slower production rateo Need people with high IT skills

displaying: – actuators – specialised display devices that perform a mechanical action under the control of the system: Actuators are devices which produce a mechanical action as an output of the AMS after receiving a signal from the controller. They are devices which do work on the product. Actuators have an effect on another system or the environment.

– types of actuators, including: - solenoid: It is a coil of wire around an iron magnetic rod. When electricity passes through it the magnet will move one way as it is in a magnetic field. When the electricity is turned off the magnet will move the other way. They are usually attached to valves which are used to open or close something, such as a pipe, e.g. in a washing machine, it adjusts the amount of water which enters the machine. - motor: These actuators are the most common types of actuators. They

are used to power many gear and lever systems which are then used for other applications. It uses electricity powered magnetism to spin a coil of wire. DC motors have an adjustable speed, while AC motors need full power for full speed.

DC motors are a smooth and continuously running motor and provide a lot of force due to its torque (twisting motion).

- stepping motor: These are motors which are able to operate on a small scale, capable of producing small, fine movements. They are used in robots and are also found in hard drive readers, where small movements are used to read the data stored. Stepping motors can make very precise movements.

Stepper motor: Converts electrical pulses into movement. Shaft rotates in small portions called steps depending on the speed of the pulses. rotates the shaft on a specific number of degrees

Advantages: Precise, can start or stop very well Errors can only go over by 3-5% maximum for each step and the

error will not go onto the next step

- relay : These actuators are used as switches. It is made from a solenoid which moves and either turns the switch on or off. It is used to control large currents with smaller currents, making it safer as the signals are also isolated from the power grid. Large voltage devices are opened using relays.- hydraulic pumps: Hydraulic fluids (usually oil) power the pumps which force it to go into piston chambers. The piston moves due to the hydraulic fluid forces and that causes a mechanical action. The fluid returns to its chambers.

can be used to lift heavy loads is quick and precise

– The conversion from digital to analog to control actuators: As digital data is binary and actuators can only work with analog data, the bits are converted into voltages so that the actuators can operate using DACs.• transmitting and receiving: – noise as the interference in a signal: Noise is interference in a signal, reducing the quality of the data and causing corruption in data. There are two types of noise: Random noise is when the interference occurs randomly and is weaker than Periodic noise. Periodic noise is regular patterns or waves which influence the signal and add onto it. Shielding is a form of protection from interference.– The causes of noise: Noise is caused by background interference, badly designed systems or electrical equipment which sends out waves. It can also come from a direct connection to the source of the noise. Another example is lightning. – Ways of correcting noise: There are different ways to fix noise:

Signal conditioning: Changing the signal itself to produce better quality Filtering: This is used for analog parts of the system. They get rid of the unwanted noise by

removing frequencies that are above and below a certain value giving a better signal, by only keeping the desired signal.

For digital signals, the most common way to correct noise is resend the data and the errors can be identified with error checking techniques such as sending start/stop parity bits.

Shielding prevents noise

issues related to automated manufacturing systems

• the changing nature at work resulting from automation in manufacturing technology: People are now being replaced by machines which can do what they can but even better and/or cheaper. Unemployment has resulted from automated manufacturing systems. It has also changed the way people work by allowing people with technology skills to have jobs such as operators. People who still work can operate differently due to the technology in AMS such as sensors and robotic arms to allow people to work much safer. The structure/schedule of which people work have changed such as operators who work on a conveyor belt can have lunch during production, maximising productivity.• the advantages of semi-automation by utilising skills of people which leads to job satisfaction, including: – flexibility: People are more flexible than machines and can work out a solution better than a programmed robotic arm.– common sense: Machines do not have common sense, which is where humans come in and use this to fix or identify problems.– ingenuity: People can think of new ideas to improve the AMS system.• the need to develop systems that are human-centred and assist participants to complete tasks, as opposed to machine-centred systems where humans assist machines: Human centred systems offer many more advantages to participants than machine centred systems. Human centred systems make work easier for the participants. It is built with a participant to understand the requirements more better. On the other hand machine centred systems are those which rely heavily on the participants to manage the machine just to form simple tasks and it may be confusing for the participants, reducing productivity.• the reliability and quality of performing repetitive tasks such as: automatic painting: Automatic painting not only allows for a better quality result as various techniques such as magnetism of the paints and calculation of the exact amount of paint are done by robots to allow an even finish.spot welding, newspaper production, computer embroidery: These tasks are repetitive and so productivity is increased and due to the programming of machines, the output is almost the same each time. As machines do not tire out they are more reliable then humans and are prone to less human errors.• the improved safety as a result of automated manufacturing: Safety has increased due to automated manufacturing systems which are doing dangerous jobs instead of people, such as spot welding. It has also increased safety by using sensors to detect whether an accident could occur and does the most appropriate action to stop the accident from occurring. However if an automated manufacturing system is badly designed it could be even more dangerous than not have an AMS.• current and emerging trends in automated manufacturing systems:Use of AMS for quality control: Quality control is achieved due to the machine’s accuracy and reliability. It is advantageous and allows most of the products to be the same.

Features of actuators Use electricity to perform a mechanical action, which does something physical to a product.

It is a display device.

Signals are received as voltages sent by the controllers which convert digital data, so that it can be understood by the actuators

o It is an analog device