A DIGITAL DISCRIMINATOR FOR A NORTHERN COMMUNICATION SYSTEM
Date
1971-03
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ORCID
Type
Degree Level
Masters
Abstract
The problem of communication with northern Canada by means of high frequency radio is briefly examined, and previous workers and their contributions are mentioned. Specifically, this project was to add modulation and demodulating capability to a previously designed and constructed system. The existing system utilized a low power (i.e. less than 100 watts) transmitter, a propagation method of forward E scatter, and a receiver coupled to a frequency compression demodulator, FCD.
The solution chosen uses standard teletype machines with ASCII binary codes modulated onto the transmitted signal in the form of frequency shift keying along with a digital method of demodulation. A method of augmenting the received signal to noise ratio when information is being sent while retaining the advantages of low power transmitting equipment is achieved by increasing the
transmitter power for a time period which allows reception of four cycles of the transmitted signal.
The digital discriminator includes a form of error correction and noise recognition circuitry. Various methods of testing the resultant system indicate that normal operational parameters of the FCD will result in a threshold of approximately 4db for seventy per cent correctness of the received signal.
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Degree
Master of Science (M.Sc.)
Department
Electrical Engineering