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Electrical and Computer Engineering

Portland State University

Theses/Dissertations

2020

Radio -- Transmitter-receivers -- Design and construction

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Design Of A 7-Mhz Portable Direct Conversion Transceiver With Digitally Controlled Keying, Abram Morphew Jun 2020

Design Of A 7-Mhz Portable Direct Conversion Transceiver With Digitally Controlled Keying, Abram Morphew

Dissertations and Theses

This thesis outlines the design of a portable direct conversion transceiver system for the 7-MHz (or 40m) band. This band is popular due to its propagation characteristics which allow for world-wide communication with very low power. The transceiver utilizes a crystal-stabilized local oscillator optimized for frequency agility, low power consumption, and an optimal drive level of +7 dBm. A low power 8-bit microcontroller acts as an interface for either a straight key providing manual Morse code operation or digital logic control from a personal computer. It also acts as a side tone oscillator providing audio feedback to the operator during …