Introduction to Engineering and Technology Concepts Unit Four Chapter Four - Telecommunications.

Introduction to Engineering and Technology Concepts

Unit Four

Chapter Four - Telecommunications

Instructions for Success:

• Each chapter of every unit will begin with a “Mindjog.” This is a warm up question that you should answer in your workbook in the proper chapter.

• Please take notes as you move through the presentations in the notebook that has been provided.

• Sections will come up in each presentation with an assignment notice. Turn to the section detailed on the slide in your workbook and complete the assignment before proceeding.

• Good luck!

Objective

• Students will define the components of telecommunications.

Mindjog!

• On your worksheet, please respond to the following question: 

• “In your own words, give a basic example of how a typical radio works.”

Telecommunications

• In Chapter 3, we briefly discussed telecommunications. For Chapter 4, we’re going to really delve into the science and math concepts.

• We stated in Chapter 3 that telecommunication really means communicating over a distance.

• One important aspect of telecommunication involves the principles of electricity and electromagnetic waves (Wright, 2004).

Electrical Principles

• All matter is made up of atom, and each atom has a nucleus (center). The nucleus is made of positively charged particles (called protons) and neutral particles (called neutrons).

• A group of negatively charged particles (electrons) orbit the nucleus and are held in this orbit due to their attraction to the protons.

• In certain situations, electrons will travel from one atom to another. This is called electricity.

• It will most often take place in a metal, known as a conductor.• When electrons are flowing in one direction along the conductor, it is called direct

current. If the electrons flow in both directions, reversing at regular intervals, it is called alternating current.

• Movement of electrons in a conductor creates magnetic lines of force. As these lines of force increase and decrease in strength, they cause the electrons to flow in an adjacent wire. This is called induction.

• When induction is used to change sounds into electrical signals or electrical signals into sounds, it occurs in transducers. Transducers change energy of one

form into another. (Wright, 2004).

Electromagnetic Waves

• Within electromagnetic waves, there are two important characteristics: frequency and amplitude.

• Frequency is the number of cycles (complete wavelengths) that pass some point in one second. The number of those cycles are measured in hertz.

• Amplitude measures the strength of the wave. The higher the amplitude, the stronger the signal.

• Telecommunication uses changes in the amplitude of the waves, the frequency of the waves, or both to carry the message.

• Radio waves are a series of frequencies. Radio waves are part of a series of frequencies known as broadcast frequencies, which include police/fire, broadcast, cellular, and television communication (Wright, 2004).

Broadcast Systems

• Broadcast systems send radio waves through the air carrying the signal from the sender to the receiver.

• Radio broadcasting was the first wide-spread broadcast medium. All radio uses carrier frequency that radiates from the transmitter.

• The earliest radios used amplitude modulation (AM) which merged the message onto the carrier wave by changing the amplitude (strength) of the carrier signal.

• Later, radio began using frequency modulation (FM) which encoded the message on the carrier wave by

changing its frequency (Wright, 2004).

Broadcast Systems (continued)

• Television broadcast systems are really two systems in one. One portion of the band is used by a radio-like system to send and receive audio. The larger portion of the band is assigned to a second system that communicates the video.

• Two basic television stations exist: VHF and UHF.• VHF stands for very high frequency and UHF stands for

ultra high frequency. Normally, VHF channels broadcast major networks and local stations due to reaching greater distances. Public broadcasting and smaller independent stations are often found on the UHF channels (Wright, 2004).

Assignment #1

• Please turn to the section in your workbook entitled, “Unit Four, Chapter Four – Telecommunications.”

• Complete the extension questions under the “Assignment #1” header before moving onto the next section of slides.

BEFORE MOVING ON:

• Did you complete the “Assignment #1” Section under the “Unit Four, Chapter Four – Telecommunications” section of your workbook?

• If you have, please proceed to the next slide.

Unit Four Completed!

• Please close this presentation and launch the file entitled, “Unit 5, Chapter 1.”

References

• Wright, R. (2004) “Technology” The Goodheart-Willcox Company, Inc.