Remote Triggered Analog Communication Electronics Laboratory for e- Learning

Remote Triggered Analog Communication Electronics Laboratory for e-Learning

C.M. Markan Department of Physics and Computer Science

Dayalbagh Educational Institute Agra, India

[email protected]

Sajal Mittal Department of Electrical Engineering

Indian Institute of Technology Kanpur, India

[email protected]

Satendra Gupta Department of Physics and Computer Science

Dayalbagh Educational Institute Agra, India

[email protected]

Goutam Kumar Department of Physics and Computer Science

Dayalbagh Educational Institute Agra, India

[email protected]

Abstract— Currently most universities have Online-learning environments ready to be remotely accessed through the internet, however in engineering education activities, the role of experimentation is a key concept. Remote Triggered Laboratories have emerged as viable alternatives in developing skills to deal with physical phenomenon and instrumentation in absence of real laboratory experience as well as to provide a sustainable option to shift from Faculty-Centric to student–centric teaching approach, which is more and more relevant in higher level education now a days. Remote laboratories can provide remote access to experiments ( and simulators as well), and can allow students to access experiments without time and location restrictions, providing the necessary guidance and constraining operation in order to avoid dangerous situations (both from set-up integrity and from the user’s point of view). The proposed Remote Triggered analog communication laboratory is designed for analog communication using NI-Elvis and Emona Datex that not only operates in a traditional one-equipment-one-user ‘interactive mode’ but also provides multi-user scalability. Keywords-Remote Triggered Laboratory, Emona-Datex, Ni-Elvis, e-learning, Analog communication

I. INTRODUCTION Present transition of education system from classrooms

(Faculty-Centric) to OnLine learning (Student-Centric) [1] teaching approach has definitely revolutionalized the past pedagogy however OnLine learning is still deficiting with basic phenomenal aspects like Laboratories. Laboratory work is an important part of the engineering course [2], in which the students can make practice of what they learned in the classes, which helps them to reinforce the learning of the concepts. Remote Triggered Laboratories are envisaged as teleoperation of physical laboratories, providing touch and feel of a real laboratory and thus proving to be a paradigm shift in OnLine Learning environment. Currently Remote Triggered Labs have

clearly shown their academic usefulness [3] and emerged as a substitute of real physical laboratories [4-5].

Despite the advantages of Remote Triggered (RT)

Labs, RT labs still face certain technological hurdles that belittle the potential applications for which they were created.--One of them is that only a single user can access and control an instrument throughout the duration of the experiment in what is termed as one-equipment-one-user ‘interactive mode’[6]. In this mode assuming that an experiment needs a one hour slot we can expect only a single user or a group of collaborative users will have access to the lab in that duration and hence no more than 24 such users would complete an experiment in a day. Given the fact that an RT lab built with sophisticated instrumentation and advanced ICT features may sometimes cost up to 10 times more than the traditional real lab, we are faced with a scenario where RT labs do not appear to be financially attractive. This may be a primary reason that despite hundreds of RT labs that have been developed in research labs only a very few have been accepted into the mainstream.

The first Remote Triggered Laboratory was developed

with covering the Basic experimentation aspects of electronics (eVALIDATE) [7] now its success has motivated us to build up Remote Triggered Laboratory for Analog Communication experiments with features like multi-user scalability [10].

In developing RT lab for Analog Communication to

conduct communication experiments (Modulation, Demodulation etc.) we have developed RT Lab that is traditionally conducted using a breadboard and electronic components we have used Emona Datex board (Plug-in module for Emona Datex trainer) and National Instrument’s Educational Remote Instrumentation Suite (NI ELVIS) [8].The DATEx [9]-ELVIS II bundle enables

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the use of a hands-on approach in teaching engineering communications concepts. However, experiments can’t be remotely performed using Labview.

To provide students a complete e-learning environment where they can find themselves comfortable and accessibility to information of theoretical concepts and basic fundamentals knowledge of experiments, a website is developed consisting information about the Laboratory, procedure to perform experiments in Remote environment and detailed information including (Theory, Introduction, Calculation, Procedure, FAQ’s) for each and every experiment. Video Tutorials are also uploaded on website providing step by step procedure to perform experiments so that it becomes easy for a student migrating from a physical laboratory to a Remote Triggered laboratory. After completing experiment on Remote Triggered laboratory, student can go back to the website and solve provided quizzes and calculate and verify his/her experiment results.

To deploy Emona Datex board in Virtual Remote

Triggered Analog Communication Electronics Lab (RT-ACE) that gives RT-ACE a traditional feel a frontend has been developed that provide students the capability to perform any communication experiment using Emona Datex blocks irrespective of the constraints to perform predefined experiments like any other RT Laboratory. In this paper in section II we describe the architectural details and front-end GUI of the innovative methodology adopted to build RT-ACE Laboratory based on Emona-Datex and NI-Elvis set up. In section III we will discuss about sustainability and scalability of Remote Triggered Labs. In section IV we will examine the RT-ACE Lab experiment results authenticity and reliability by comparing experimental data without physical Lab experiment results. In section V we will also point out few major differences between RT-ACE Lab with other available Remote Triggered Labs.

II. LAB ARCHITECTURE In order to perform communications experiments using the ELVIS II-DATEx setup in a remote laboratory environment, there is a need for eliminating the user interface needed to perform the required connections for the DATEx modules and to provide extendibility to wiring circuits from client-side, which is accomplished by using a Agilent LXI switching matrix. Client-Server Architecture as shown in Figure1 for RT-ACE is a generic platform developed for Ni-Elvis and Emona-Datex. Unlike other Remote Triggered Labs that have been build up using Ni-Elvis and Emona Datex with each Laboratory deficits the requirement of a scalable model to justify the cost of expensive instruments utilized in Remote Triggered Labs, this platform provides architecture to build up a scalable model of Remote Triggered Labs using Elvis-Datex setup. Presented architecture also denies the requirement of Labview run time engine on client side. To setup a scalable model of

Figure1. Client Server Architecture of Remote Triggered Analog

Communication Electronics Lab

Elvis-Datex, we have designed a animated oscilloscope which displays the plot of data acquired from Ni-Elvis- Emona Datex setup provides a feel and illusion of a real oscilloscope. Figure2 shows the design of animated oscilloscope. This architecture provides a rigorous mechanism of acquiring and displaying the acquired data from Ni-Elvis-Datex setup. To work in scalable environment, SSH server has been setup to communicate between Linux Main server and Ni-Elvis Data acquisition board. Elvis-Datex can be setup behind a reverse proxy server to restrict direct access to instruments. Labview VI’s are converted into dll (Dynamic Link Libraries) and run through command line using Microsoft Visual Studio.

This setup allows clients to obtain real data by wiring up a circuit in the laboratory using GUI of a Datex Virtual breadboard, devices and instruments on the Web all through remote access over the internet.

A. Emona DATEx board The Emona DATEx trainer is a plug-in module for the ELVIS platform. The DATEx- ELVIS II bundle enables us to use hands-on approach in teaching engineering communications concepts. Datex blocks provide students a fundamental approach in a bottom up manner (Block Diagram Approach). Students can easily implement theoretical concepts in labs by using block diagram

Figure2. Design of animated oscilloscope

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approach used as standard notations in text books to describe mathematical equations. We have shown the photograph (Figure3) of Emona-Datex Board set up in our Laboratory. Students can log in and perform any experiment by wiring up circuit on a GUI (virtual Datex Board).

B. LAN extension for Instrumentation (LXI) Most instrument interface standards such as GPIB, PCI, PCI-X or USB need specialized physical ports, drivers and interfacing software before any communication is possible with an instrument. In contrast LAN based instruments are neither localized nor limited by number of ports on computer. Although Ethernet has been used in this role for some time, the problem is that the there was no standard and the way instruments communicate over Ethernet varies from one instrument to the next. It is this problem that LXI seeks to address. It sets standards for instruments to have an embedded Web-server, a SCPI language compiler and conformation to IVI and VISA standards. We have utilities Agilent's LXI c class based switching matrix to interface Emona-Datex to perform required connections.

C. NI-ELVIS II National Instruments Education Laboratory Virtual Instrumentation Suite (NI-Elvis II) consists of Labview-based virtual instruments, a multifunction data acquisition (DAQ) device. We have used NI-Elvis's instruments – Multimeter, Analog two channel oscilloscope, Function generator, variable power supply, digital signal analyzer. Ni-ELVIS web server interface allows each instrument to be readily controlled and observed from the Web on real-time basis. The data acquisition interface allows students to make real-time data acquisitions on the Web. When an instrument is requested by clicking on it in the Web window, a window pops up showing instrument controls

for the instrument them and the reading of the instrument as shown in Figure4. The instrument settings can be changed by the controls on the Web containing control knobs and buttons on the client computer screen.

D. Virtualization Software All the virtualization software is done in HTML, JavaScript, Java, Visual C, Labview, shell script and in Perl language for the CGI interface. The HTML, JavaScript and the Java reside in the Main server. Labview web server resides on a windows system connected to Datex-Elvis II set up. Labview web server provides NI-Elvis instrument panels (as shown in Figure 4) to remote clients. Microsoft Visual Studio provides a platform to run Labview built DLL’s (Dynamic Link Library) also resides on windows system, Cygwin environment has been set up for interfacing windows system with the Main Linux server to acquire and send data between Main server and Data acquisition Board (Datex-Elvis II).The Web-based software are, written in HTML, JavaScript, Labview and Java, integrates the virtual breadboard, components, scope, Emona-Datex controllable knobs and waveform generator (customized in Labview). Figure 5 shows a Web capture of the circuit wired on the virtual Emona DATEx board just like any student will do in a normal laboratory.

D. Frontend GUI (Virtual Datex Breadboard) To provide accessibility of Emona-Datex and Ni-Elvis in remote laboratory with flexibility to wire up a circuit by patching up Datex blocks is been made possible using a

Figure4.  Upper  image  shows  the  virtual  control  panel  of  RT-­‐ACE  Lab  with  all  the  knobs  and  lower  image  shows  the  actual  NI  ELVIS  control  

panel

Figure3. Hardware Setup of Remote Triggered Analog Communication Electronics Lab

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Agilent switching Matrix and a Web-based GUI for Emona Datex (Emona Datex Virtual Board), Figure5 shows a typical Web-based “Emona Datex Virtual Board” which is a photograph of a real Datex board. The user is able to patch up any Datex blocks over the Datex virtual breadboard as desired to accomplish the necessary wiring. When the user completes the circuit and presses a “run” button, the software at the host analyzes the circuit to extract a net-list i.e. determines which hardware pins are connected together, Figure6 explains connection diagram of Datex-Elvis II set up. The pin connections represent nodes. The circuit may be wired (correctly or incorrectly) on any portion of the Datex virtual breadboard on the Web but the software turns on only the appropriate relays to connect the circuit wired on the Datex virtual breadboard. RT-ACE web-page appears like a dashboard that shows a summarized view of all involved instruments and a virtual Datex breadboard. The representative buttons provide a way to open up elaborate front panels of the measurement instruments, while the display panels of these instruments convey essential information for quick view. Background software ensures electrical rules and breadboard topology are encoded so as to extract an electrical circuit from the virtual Datex breadboard GUI. The RT-ACE interface is greatly simplified by using a graphical interface to allow the students to experience the frustrations and hands-on experiences of a real-world laboratory environment. A student trained on these virtual panels is not likely to feel out of place in a real laboratory see Figure 2, 4, and 5. RT-ACE backend consist two components (i) the virtual Datex breadboard, and (ii) the relay matrix. The virtual Datex breadboard is a java program that allows user to draw up a schematic which results in a netlist. The relay matrix containing fixed devices and customized relays provides realization of the circuit netlist. Student draws up

the schematic on the virtual Datex breadboard, connects different Datex Blocks and Instruments such as Master Signal, function generator, and Oscilloscope as needed. When the student presses the Run button, requirement to infer connectivity from the schematic and create the same connectivity physically in the lab by closing specific relays on the relay matrix. Thus by closing specific relays, selected devices can be connected in any desired topology, thus matching the circuit to be drawn.

III. SUSTAINABILITY AND SCALABILITY In initial stage, every technology faces difficulties and challenges and requires a great effort to replicate and replace the other. There are several factors e.g. Feasibility, sustainability, affordability etc. that comes into consideration at the time of implementing the technology and it’s adaption but once the technology has evolved and perfectly matured, primary concern remains the sustainability. Remote Triggered Laboratories uses high cost instrumentation which is more precise then physical laboratory instruments. To justify the cost of the expensive instrumentation used to build up Remote Triggered Laboratory, multiuser scalability is a necessary mechanism providing simultaneous access to multiple users in real time frame. We have invoked a queuing mechanism to precede request on first come first server basis in quick sequential steps seen as rapid switching of the relays on the hardware. The average hardware verification time for each user was nearly one second. Under ordinary circumstances, it is unlikely that all users will request hardware verification simultaneously, in such a situation each of the user’s hardware requests is attended almost immediately within a second.

Figure5. Webpage of Remote Triggered Analog Communication Electronics Lab through which user can perform any experiment

Figure6. Connection Diagram of Remote Triggered Analog Communication Electronics Lab

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IV. COMPARISON OF EXPERIMENTAL DATA While performing analog communication experiments, noise plays a crucial role in obtaining appropriate experiment results otherwise in presence of noise student will never be able to get the desired output results of his experiment. So there is a need to verify the results obtained from Remote Triggered Lab to prove its authenticity and reliability in analog communication. To verify the experimental results and data of Remote Triggered Laboratory obtained from real hardware in real time, we performed Double sideband suppressed carrier experiment (with variable frequency and variable amplitude message signal and 1Vpp, 100 kHz carrier signal) and analyzed the experimental results obtained. Again we performed the same experiment in offline manner (without using Remote Lab) and verified the results obtained in both conditions. We noted down the Signal-to-Noise Distortion Ration (SINAD) in dB and Total Harmonic Distortion (THD) in both the cases. THD is zero in both the case and slight variation in SINAD is observed as shown in Table I and II. Figure 7(a) shows the message signal and DSB-SC signal without using RT-ACE Lab and Figure 7(c) shows its corresponding FFT of DSB-SC Signal having two frequency band and SINAD value in dB and also THD at the bottom of figure similarly Figure 7(b) shows the message signal and DSB-SC signal by using RT-ACE Lab and Figure 7(d) shows the corresponding FFT of DSB-SC signal having two frequency band and SINAD value in dB and also THD at the bottom of figure. Now on the basis of the above results as compared in both the conditions we find almost same results. Signal-to-Noise Distortion Ration is almost similar in both the cases so we can say that performing experiment by RT-ACE lab doesn’t add any additional noise in the output of experiment. Hence these results justify our statement of using RT Labs in e-Learning environment.

TABLE I SINAD IN DB BY PERFORMING DSB-SC EXPERIMENT WITH THE RT-

ACE LAB

Amplitude(Vpp) Frequency(kHz)

2 4 6 8 10

2 3.05 2.98 2.99 3.05 2.91 4 3.08 2.96 2.96 3.07 2.92 6 3.07 2.97 2.95 3.08 2.93 8 3.08 2.96 2.95 3.07 2.93

10 3.06 2.95 2.96 3.06 2.92

TABLE III SINAD IN DB BY PERFORMING DSB-SC EXPERIMENT WITHOUT THE RT-

ACE LAB

Amplitude(Vpp) Frequency(kHz)

2 4 6 8 10

2 3.05 2.96 2.99 3.06 2.91 4 3.07 2.96 2.95 3.08 2.93 6 3.06 2.95 2.96 3.08 2.91 8 3.08 2.96 2.95 3.06 2.92

10 3.05 2.95 2.96 3.07 2.92

(a) (b)

(c)(d)

Figure 7:- (a) Shows the Message and DSB-SC signal without using RT-ACE lab, (b) Shows the Message and DSB-SC signal by using RT-ACE lab, (c) FFT of DSB-SC Signal obtained by not using RT-ACE Lab, (d)

FFT of DSB-SC Signal obtained by using RT-ACE Lab

V. COMPARSION WITH OTHER REMOTE LABS These are few points of comparison between Remote Triggered Analog Communication Lab and other Remote Labs available as shown in table 1.

RT-ACE Lab Other Virtual Labs Modes of Operation

Batch Mode and One Shot (time 1

to 3 seconds)

Batch Mode and Interactive Mode (time 10 to 100

seconds) GUI User can wire up

arbitrary circuit Can’t wire up

arbitrary circuit Labview Runtime

Requirement

Not Necessary Necessary

Switch Matrix Agilent 34980A, 64 switch [16

32] , 8 Slot

NISCZI 1169, 100 Switch [18 29], 4

slot Table1. Comparison between RT-ACE and other Remote Labs

VI. CONCLUSION

In comparison with traditional e-contents (virtual Classrooms, e-projects) remote laboratory conception implies additional difficulties. These difficulties are due to

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teleoperation requirements providing touch and feel of a real lab. The user must be given the ownership of the hardware where he/she can design and execute an experiment of choice that includes all the pitfalls of real lab experiment i.e. making wrong wiring, debugging a circuit and feeling of jubilation at overcoming challenges. In this work, we presented a setup that can be used to perform Analog communications experiments remotely in a distance learning environment. We have also summarized the comparison of RT Lab experiment results with physical Lab experiment results. Current RT-ACE Lab set up is a scalable model of Ni-Elvis and Emona Datex and provides a pedagogically rigorous mechanism of instructions for students to perform analog communication experiments using concepts of block diagram approach.

ACKNOWLEDGMENT The author CMM acknowledges MHRD GOI for the

financial support under NMEICT Nationally Coordinated Project on Virtual Labs.

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