Pulse or digital communications – Repeaters – Testing
Patent
1983-06-24
1986-02-25
Griffin, Robert L.
Pulse or digital communications
Repeaters
Testing
375 54, 375 67, 375 86, 329112, 332 21, H04L 2718, H03C 300, H03D 300
Patent
active
045731667
ABSTRACT:
An all digital modem includes a clock divider for generating four waveforms at a desired transmission frequency but mutually phase shifted by 90 degrees, a first microprocessor programmed to receive digital data at its input, to convert the data into dibits and to select as a modem output one of the four waveforms phase shifted 90 degrees with respect to each other. To demodulate incoming signals, a zero crossing detector detects zero crossings of an incoming modulated signal, a second microprocessor coupled receives the zero crossing information along with parity information and converts the information into dibits, and a third microprocessor receives dibit outputs from the second microprocessor and converts the dibits into a serial stream of data, at essentially constant frequency.
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Glenny Raymond C.
Griffin Robert L.
Wolfdata, Inc.
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