Britt Fidler

Publication Date


Document Type


First Advisor

Hashemian, Reza

Degree Name

B.S. (Bachelor of Science)

Legacy Department

Department of Electrical Engineering


Phase shift keying (PSK) is a phase modulation method for communication. Phase shift keying at 31.25 baud (PSK31) modulates a carrier signal at 31.25 Hz [1-8]. There are several flaws (i.e., natural or otherwise) in the current method of PSK31. This PSK31 modem utilizes field programmable gate arrays (FPGAs) to solve the problems and glitches of the current PSK31 method. This capstone project focuses on taking the information available for the current method of PSK31 and the information available for software-defined radio, and then merging and modifying it in order to develop a PSK31 modem. The PSK31 modem modulates and demodulates a PSK signal from ASCII to Varicode or vice versa. In order to modulate, the PSK31 modem (1) accepts data, (2) converts the data to phase modulated pulses, and (3) converts the pulses to an analog signal. In order to demodulate, the PSK31 modem (1) shapes, compensates, and converts the analog signal into a digital signal, (2) decodes the digital signal, and (3) displays the data.


Includes bibliographical references.||Missing pages 33, 50, and 86.


109 pages




Northern Illinois University

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Alt Title

The Phase Shift Keying 31 modem

Media Type