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A Psk31 Audio Beacon Project Provides A Laboratory Capstone Design Experience In Digital Communications

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Conference

2008 Annual Conference & Exposition

Location

Pittsburgh, Pennsylvania

Publication Date

June 22, 2008

Start Date

June 22, 2008

End Date

June 25, 2008

ISSN

2153-5965

Conference Session

Electrical ET Curriculum and Projects

Tagged Division

Engineering Technology

Page Count

18

Page Numbers

13.93.1 - 13.93.18

Permanent URL

https://peer.asee.org/3752

Download Count

102

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Paper Authors

biography

James Everly University of Cincinnati

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James O. Everly is an Associate Professor of Electrical and Computer Engineering Technology at the University of Cincinnati. He received a BSEE and MSEE from The Ohio State University in 1969 and 1970, respectively. He is a Senior Member of the Institute of Electrical and Electronics Engineers (IEEE) and a registered professional engineer in the state of Ohio. He is the current past Chair of the IEEE Cincinnati Section, and in 1997 he received the IEEE Professional Achievement Award. He has held several research and management positions in industry working for such companies as Battelle's Columbus Laboratories, Rockwell International, and Claspan Corporation. He joined the University of Cincinnati in 1985.

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Brian Resnick University of Cincinnati

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Brian Resnick is an Assistant Professor of Electrical and Computer Engineering Technology at the University of Cincinnati. He received a BSEE and MSEE from The University of Cincinnati and is a Senior Member of the Institute of Electrical and Electronics Engineers (IEEE) and a registered professional engineer in the state of Ohio. He is the current Chair of the IEEE Cincinnati Section. His speciality is software engineering and prior to joining the university he had a software consulting business. He joined the University of Cincinnati in 2005.

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

A PSK31 Audio Beacon Project Provides a Laboratory Capstone Design Experience In Digital Communications

Abstract

This paper focuses on combining a 433.92 MHz wireless temperature sensor with a PSK31 Audio Beacon transmitter to provide a laboratory capstone experience for junior students in Electrical and Computer Engineering Technology. The laboratory capstone PSK31 Audio Beacon Project is structured to support course goals and objectives of "Digital Communications" offered at the beginning of the junior year. The paper presents the "project concept" together with its theory of operation and project schematic. Also, students are required to build a prototype audio beacon transmitter using surface mount components, implement a packaging concept, and write a complete project specification. The secondary goals of the project are to introduce students to radio frequency (RF) amplifier concepts, and to prepare students for the upcoming Senior Design Capstone Experience required for a baccalaureate degree in engineering technology. To this end, students are required to maintain a project journal to record ideas, data, test results, and experiences throughout the project. The authors have found that student attitude towards the course and subsequent feedback to be most rewarding, and were very encouraged by the level of student involvement in the project.

Introduction

Over the past four years a phase shift keying (PSK31) Audio Beacon project has been introduced to a group of students in a Digital Communications at the University of Cincinnati. After a couple of iterations of the project, the authors noticed that student comments on the “project evaluation” form tended to center around adding additional capabilities to the project in order to make it more interesting. This paper is a direct result of those student evaluations together with a conscientious attempt on behalf of the authors to utilize projects in the laboratory portion of the course to stimulate student interest in RF communication concepts.

This laboratory capstone project illustrates the integration of a 433.92 MHz wireless temperature sensor into a PSK31 modulated audio beacon transmitter. The temperature sensor is a Dallas Semiconductor DS18S20 integrated with a standard "off-the-shelf" 433.92 MHz RF transmitter module that uses amplitude modulation. The transmission method known as "On-Off Keying (OOK)" transmits the temperature data by simply switching the carrier signal on and off. The RF data-link serial receiver can be located up to 500 feet from the transmitter and interfaces to the PSK31 Audio Beacon via an RS232 interface. The Audio Beacon features PSK31 encoding and audio waveform generation using a single-chip SX28 RISC microcontroller operating at 50 MHz. The beacon has a choice of three base carrier audio frequencies, namely: 500 Hz, 1 kHz, and 2 kHz. As an added bonus, students are introduced to RF amplifier concepts by taking the output from the audio beacon and injecting the audio signal into the microphone input of a five watt single-sideband transmitter. To form a conventional RF Beacon operating on 3.579 MHz (Amateur Radio 80 meter band), the output of the Class AB push-pull RF power amplifier is sequentially reduced by switching in-line a series of 3 dB attenuators until the output power reaches 0.63 watts. The transmit Beacon data string consists of station identification (Amateur

Everly, J., & Resnick, B. (2008, June), A Psk31 Audio Beacon Project Provides A Laboratory Capstone Design Experience In Digital Communications Paper presented at 2008 Annual Conference & Exposition, Pittsburgh, Pennsylvania. https://peer.asee.org/3752

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