Demonstration and Simulation of Dispersion in Coaxial Cables with Low Pass Filters - A Teaching Laboratory Experiment

Alex Francis Katauskas; Wenli Huang

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Conference: 2017 ASEE Annual Conference & Exposition
Location: Columbus, Ohio
Publication Date: June 24, 2017
Start Date: June 24, 2017
End Date: June 28, 2017
Conference Session: Electrical and Computer Division Poster Session
Tagged Division: Electrical and Computer
Page Count: 12
DOI: 10.18260/1-2--28103
Permanent URL: https://peer.asee.org/28103
Download Count: 1998

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Paper Authors

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Alex Francis Katauskas Defense Threat Reduction Agency

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Major Alex F. Katauskas graduated from the U.S. Naval Academy in 2002 with a B.S in Economics, and graduated from Rensselaer Polytechnic Institute in 2013 with a M.S. in Physics. He served as an instructor in the Department of Physics and Nuclear Engineering at the U.S. Military Academy, West Point, NY for two and a half years. He is a member of the Sigma Pi Sigma honor society. He is currently serving at the Defense Threat Reduction Agency.

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Wenli Huang U.S. Military Academy

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Wenli Huang is a Professor of Electrical Engineering at the Department of Electrical Engineering and Computer Science at the U.S. Military Academy, West Point, New York. She received her Ph.D in electrical engineering from the University of Connecticut. Her research interests include halftone image processing and design/modeling of nanostructure optoelectronic devices. She is a Senior Member of IEEE and a member of Phi Kappa Phi and Eta Kappa Nu honor societies.

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Abstract

Data suggest that continuous time signals and systems (CTSS), and its underlying concepts, can be difficult for students to grasp. CTSS and Electromagnetics courses at certain universities experience drop/failure rates 2-3 times higher than other required courses. Likewise, the phenomenon of absorption and dispersion is only briefly discussed in most undergraduate Electromagnetic and CTSS textbooks. This paper proposes a new teaching technique of simulating and modeling the attenuation and dispersion in a communication cable using low pass filters on a signals processing board. In our study, we used a RG-59 60 meters coaxial cable. With a function generator and an oscilloscope, we were able to observe dispersion and attenuation at high frequencies. We then used a gain-phase analyzer to measure the attenuation and phase shift produced by the cable as a function of frequency. Our results suggest the frequency response of the cable is very much like a low pass filter. The students can use the response to construct a set of filters on a signals processing board that will approximate the dispersion and attenuation observed in the cable, thus gain a better understanding of both concepts. The attenuation and dispersion can also be modeled by students using Fourier Series. At the input, any periodic square pulse signal can be expressed as a weighted sum of infinite number of sine and cosine functions. At the output, the individual frequency components are modified with a new amplitude and phase term based on the measured frequency response of the cable, and combined to give a distorted signal.

One goal is to provide a hands on learning experience for students in order to reinforce their understanding of attenuation and dispersion. Another is to reinforce the concept of Fourier analysis in modeling the input and output signals, and gain an appreciation for how a linear system modifies the amplitude and phase of a signal to produce an output signal. In this case, the dispersion and attenuation are undesired effects of the coaxial cable which can distort the output signal at higher frequencies. Lastly, the construction of the filters allows students to see how two different systems with the same transfer function can produce a closely similar output signal from an input signal.

We would prefer a poster session presentation.

Citation
Format

Katauskas, A. F., & Huang, W. (2017, June), Demonstration and Simulation of Dispersion in Coaxial Cables with Low Pass Filters - A Teaching Laboratory Experiment Paper presented at 2017 ASEE Annual Conference & Exposition, Columbus, Ohio. 10.18260/1-2--28103

TY  - CPAPER
AB  - Data suggest that continuous time signals and systems (CTSS), and its underlying concepts, can be difficult for students to grasp.  CTSS and Electromagnetics courses at certain universities experience drop/failure rates 2-3 times higher than other required courses.  Likewise, the phenomenon of absorption and dispersion is only briefly discussed in most undergraduate Electromagnetic and CTSS textbooks.  This paper proposes a new teaching technique of simulating and modeling the attenuation and dispersion in a communication cable using low pass filters on a signals processing board.
  
In our study, we used a RG-59 60 meters coaxial cable. With a function generator and an oscilloscope, we were able to observe dispersion and attenuation at high frequencies. We then used a gain-phase analyzer to measure the attenuation and phase shift produced by the cable as a function of frequency. Our results suggest the frequency response of the cable is very much like a low pass filter. The students can use the response to construct a set of filters on a signals processing board that will approximate the dispersion and attenuation observed in the cable, thus gain a better understanding of both concepts.
  
The attenuation and dispersion can also be modeled by students using Fourier Series. At the input, any periodic square pulse signal can be expressed as a weighted sum of infinite number of sine and cosine functions. At the output, the individual frequency components are modified with a new amplitude and phase term based on the measured frequency response of the cable, and combined to give a distorted signal. 

One goal is to provide a hands on learning experience for students in order to reinforce their understanding of attenuation and dispersion.  Another is to reinforce the concept of Fourier analysis in modeling the input and output signals, and gain an appreciation for how a linear system modifies the amplitude and phase of a signal to produce an output signal.  In this case, the dispersion and attenuation are undesired effects of the coaxial cable which can distort the output signal at higher frequencies.  Lastly, the construction of the filters allows students to see how two different systems with the same transfer function can produce a closely similar output signal from an input signal.

We would prefer a poster session presentation.

AU  - Alex Francis Katauskas
AU  - Wenli Huang
CY  - Columbus, Ohio
DA  - 2017/06/24
PB  - ASEE Conferences
TI  - Demonstration and Simulation of Dispersion in Coaxial Cables with Low Pass Filters - A Teaching Laboratory Experiment
UR  - https://peer.asee.org/28103
DO  - 10.18260/1-2--28103
ER  -