Dissertation/Thesis Abstract

Design of a 7-MHz Portable Direct Conversion Transceiver with Digitally Controlled Keying
by Morphew, Abram, M.S., Portland State University, 2020, 81; 27735832
Abstract (Summary)

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 keying and reducing circuit complexity. Switching field-effect transistors (FETs) were used to change from transmit to receive with a switching speed of less than 300 microseconds and allowing for full break-in functionality. For the transmitter portion of the design, a dual-stage power amplifier was developed capable of power output levels greater than 30 dBm. Transmission tests were received at several locations ranging from Calgary, Canada to Tucson, Arizona having a maximum propagation distance of 1103.5 miles from the transmitter source.

Indexing (document details)
Advisor: Bass, Robert
Commitee: Pejcinovic, Branimir, Sanchez, Erik
School: Portland State University
Department: Electrical and Computer Engineering
School Location: United States -- Oregon
Source: MAI 82/3(E), Masters Abstracts International
Source Type: DISSERTATION
Subjects: Electrical engineering, Engineering
Keywords: Analog, Design, Digital, Hardware, Radio, Transceiver
Publication Number: 27735832
ISBN: 9798664783070
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