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Analog Communications Using Infrared Transmission

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1996 Annual Conference


Washington, District of Columbia

Publication Date

June 23, 1996

Start Date

June 23, 1996

End Date

June 26, 1996



Page Count


Page Numbers

1.80.1 - 1.80.6

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Paper Authors

author page

Thomas E. Russell

author page

David R. Loker

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NOTE: The first page of text has been automatically extracted and included below in lieu of an abstract

Session 1547


David R. Loker, Thomas E. Russell The Pennsylvania State University at Erie The Behrend College


The Baccalaureate Electrical Engineering Technology program at Penn State University at Erie, The Behrend College, offers a two-semester course sequence in communication systems. The first course is intended to introduce the fundamentals of analog communication systems, while the second course is intended to introduce the more advanced communication systems topics including digital/data communications and high frequency communication techniques. During the first course in analog communication systems, the students are introduced to communication circuits, Fourier series, noise analysis, amplitude modulation, frequency modulation, transmission lines, and antennas. Along with the lecture material, the students meet weekly in the lab for experimentation. Since the fundamentals of analog communications have been in existence for many years, there is a need to introduce current technology to students in this course.

In this paper, an innovative use of current technology within analog communication systems is presented. This paper describes a laboratory project which uses infrared transmission techniques with amplitude modulation for voice communications. The purpose of the laboratory project is to introduce the design for an AM transmitter/receiver which uses an infrared LED and a photodetector for infrared transmission and detection of voice signals.

First, a series of week] y lab experiments for students are presented to complete the overall lab project. This includes the design of an infrared transmitter which consists of the design of an AM modulator using an IC oscillator, the design of a pre-amp, and the design of a common-emitter transistor driver circuit for an infrared LED. The infrared receiver consists of a photodetector connected to an op-amp for current-to- voltage conversion, op-amps for amplification and filtering, a precision peak detector for demodulation, and an audio power amplifier to drive the speaker.

Next, results are presented to show what the students learned. This includes using IC oscillators for amplitude modulation, driver circuits for infrared LEDs, switching speed limitations for infrared LEDs and photodetectors, photodetector circuits, high-speed op-amps for improved frequency response, noise reduction techniques, and peak detector circuits.

Lastly, students’ reactions are presented. Based upon their comments, much enthusiasm and interest was generated over this project, and most students were able to successful y complete the entire project.

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Russell, T. E., & Loker, D. R. (1996, June), Analog Communications Using Infrared Transmission Paper presented at 1996 Annual Conference, Washington, District of Columbia.

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