Pulse or digital communications – Repeaters – Testing
Patent
1981-02-20
1983-08-09
Buczinski, S. C.
Pulse or digital communications
Repeaters
Testing
179 1555R, 328166, 328167, 375 13, 375 15, 455 46, H04M 170, H04B 100
Patent
active
043980627
ABSTRACT:
Source intelligence within a predetermined bandwidth is normally provided to a transmission channel having a bandwidth constraint of the predetermined bandwidth. For privacy transmission, a first pulse train indicative of the source intelligence is derived and is enciphered by addition of pseudo-random values to the pulses, either directly or modulo some specified constant. The enciphered pulse train is converted to first and second symbol pulse trains at subharmonic frequencies of the first pulse train. Energy within a selected spectrum is derived from each symbol pulse train, such as by filtering, and used to modulate first and second channels of a quadrature modulator having a carrier frequency centered within the predetermined bandwidth. A suppressed carrier quadrature modulated output is transmitted along with a carrier frequency component. Receiving means include a quadrature demodulator and means for reconstructing symbol pulse trains and means for reconstructing an additively enciphered pulse train from symbol pulse trains. The enciphered pulse train is provided to an adaptive filter and deciphering means for provision of an output to an intelligence utilization means. A training mode of operation is also provided in which calibrating information is transmitted from enciphering means to the deciphering means. Weights of the adaptive filter may be adjusted during the training mode, and the adaptive filter is synchronized to sample each transmitted symbol several times.
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Glover Edward B.
McRae Daniel D.
Perkins Frank A.
Buczinski S. C.
Harris Corporation
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