Modulators – Amplitude modulator – Nonlinear device controlled by modulating signal
Patent
1983-07-27
1985-03-12
Grimm, Siegfried H.
Modulators
Amplitude modulator
Nonlinear device controlled by modulating signal
332 9R, 332 16R, 332 22, 375 52, 375 67, H04L 2720
Patent
active
045048029
ABSTRACT:
An improved four-phase differential phase shift keyed modulator for use in a modem is shown. A microprocessor (15) generates two vectors of equal frequency and equal magnitude, but different relative phases, by reference to a cyclic sine table contained in a read only memory (22). Values of the two vectors are summed and provided as an output (32) to a digital to analog converter (35). The phase shift of the carrier in a phase plane with reference to a predetermined reference phase (86) shows that the path taken by a vector in the phase plane defines a straight line (88) between two phase values by which dibits are encoded. The result is lower out-of-band transmitted signals resulting in a relatively simple transmit filter (37).
REFERENCES:
patent: 3128343 (1964-04-01), Baker
patent: 4049909 (1977-09-01), Peck
patent: 4327439 (1982-04-01), Gockler et al.
"A MOS/LSI Multiple-Configuration 9600 BPS Data Modem", by Logan and Forney; Proceedings of the 1976 IEEE International Conference on Communications.
"A New Multilevel Modulation and Demodulation System for Carrier Digital Transmission" by Ishio et al.; 1976 IEEE International Conference on Communications.
"The Design of Modems for Digital Data Communication" by Kretzmer; 1976 IEEE International Conference on Digital Communications.
"Microprocessor Controlled 4800 B/S Modem: Lower Cost Versatility", by Walsh and Shum; Proceedings of the 1979 IEEE International Conference on Communications.
"Multiprocessor Architecture for Voiceband Data Processing (Application to 9600 BPS Modem)" by Murano et al.; Proceedings of 1979 IEEE International Conference on Communications.
"A 4800 Bit/s Microprocessor Data Modem" by Watanabe et al.; vol. COM-26, No. 5, IEEE Transactions on Communications, May 1978.
"Implementation of High Speed Data Sets with Microprogrammable Data Processors" by Caplin et al.; Proceedings of the IEEE 11th Annual Microprogramming Workshop, Nov. 1978.
"Digital Implementation of an FFSK Modem" by Matyas et al.; Conference Record of the IEEE 1978 National Telecommunications Conference.
"A PSK Modem Employing Microprocessor-Based Digital Signal-Processing Techniques" by Kirkpatrick et al.; Proceedings of the 1977 IEEE International Conference on Communications.
"Microprocessor Implementation of High-Speed Data Modems" by Van Gerwen et al.; vol. COM-25, No. 2, IEEE Transactions on Communications, Feb. 1977.
"Microprocessor Implementation of Data Modems" by Snijders; Proceedings of IEEE Eurocon 1977 Conference on Communications.
Grimm Siegfried H.
Hayes Microcomputer Products, Inc.
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