Pulse or digital communications – Apparatus convertible to analog
Patent
1995-03-20
1996-05-21
Chin, Stephen
Pulse or digital communications
Apparatus convertible to analog
375200, H04L 2560, H04L 2564
Patent
active
055197256
ABSTRACT:
The present invention provides a novel Geometric Harmonic Modulation (GHM) system. The GHM system operates in two modes, a preamble mode and a traffic mode. During the preamble mode, n+1 frequencies are each offset by a predetermined phase offset in a transmit unit and passed through a channel to a receive unit. The set of phase offsets is used as the spreading code in the transmit unit, and also acts as an `address` of receive units to transmit to. The receive unit monitors preamble signals to determine the phase offsets. When it recognizes a set of phase offsets, or `address`, which pertains to itself, the receive unit stores the phase offsets and uses these phase offsets to despread and decode the appended message. After the preamble mode is finished, the transmit unit enters the traffic mode and requests the message to be transmitted from the message source. A traffic carrier waveform is created by multiplying tones, each having its specific phase offset. Both analog or binary message are provided by a switching device in interleaved fashion to an appropriate modulator which encode the messages in the traffic carrier waveform. The receive unit detects a preamble carrier and recovers the particular preamble phase offsets to be used as the despreading `key`. The receive unit then senses then separates the binary from analog message signals and employs the phase offsets in despreading the received signal to recover the transmitted analog and binary messages in an interleaved fashion.
REFERENCES:
patent: 5311542 (1994-05-01), Eder
U.S. patent appliction entitled "Dynamic Code Division Multiple Access Communication System", (Attorney Docket No. RD-24193) J. E. Hershey, A. A. Hassan, G. J. Saulnier.
U.S. patent application entitled "Method of Geometric Harmonic Modulation (GHM)", (Attorney Docket No. RD--23786), J. E. Hershey, G. J. Saulnier, A. A. Hassan.
U.S. patent applicaiton entitled "Geometric Harmonic Modulation (GHM)--Digital Implementation", (Attorney Docket No. RD-24194), J.E. Hershey, G. J. Saulnier, A. A. Hassan.
U.S. patent application entitled "Correction of Multipath Distortion in Wideband Carrier Signals", (Attorney Docket No. RD-24196), J. E. Hershey, G. J. Saulnier.
U.S. patent application entitled "Geometric Harmonic Modulation (GHM)--Analog Implementation", (Attorney Docket No. RD-24203), J.E. Hershey, G. J. Saulnier, A. A. Hassan.
U.S. patent application entitled "Interlaced Geometric Harmonic Modulation", (Attorney Docket No. RD-24223), J.E. Hershey.
Hershey et al. "Multiplexed Synchronization: An Electronic Warfare Countermeasure", IEEE Trans. on Communications vol. 39 No. 6 Jun. 1991.
Hassan Amer A.
Hershey John E.
Saulnier Gary J.
Chin Stephen
General Electric Company
Snyder Marvin
Webster Bryan E.
Zale Lawrence P.
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