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US 4,355,397 AGranted
Full duplex communication system for voice grade channels
AssigneeRixon, Inc.
InventorRichard L. Stuart
Life of this patent
Estimating the term…
Abstract
A pair of full duplex modems (12, 14), each at one end of a two-wire voice grade telephone channel (16), simultaneously transmit synchronous data at high speeds in both directions. In each modem, the simultaneous transmission and reception are accomplished by frequency division. The high speed operation is obtained by odd/even bit stream division and full response binary to ternary level coding coupled with nine level quadrature amplitude modulation and correction framing techniques.
Claims35
Apparatus for modulating and demodulating a signal comprising:
- transmitter means comprising:
- means for splitting a series of input binary data bits into an even bit stream and an odd bit stream;
- means for converting said binary data bit streams into respective streams of multi-level encoded data characters;
- means for modulating one of said multi-level encoded data character streams by an in-phase carrier signal;
- means for modulating the other said multi-level encoded data character stream by a quadrature carrier signal;
- and
- means for summing said modulated carrier signals to produce a multi-level quadrature amplitude modulated output signal;
- and
- receiver means comprising:
- means for splitting a received multi-level quadrature amplitude modulated signal into n-phase and quadrature components;
- means for demodulating said in-phase and quadrature signal components to produce first and second streams of multi-level encoded data characters;
- means for decoding said first and second streams of multi-level characters into respective streams of binary data bits;
- and
- means for combining said binary data bit streams to produce an output data bit stream representative of the information borne by said multi-level quadrature amplitude modulated signal.
11 more elements
A full response QAM modulator and demodulator system comprising:
- transmitter means comprising:
- means for splitting a series of input binary data bits into two data bit streams;
- means for converting said binary data bit streams into respective streams of ternary level encoded data characters;
- means for modulating one of said ternary level encoded data character streams by an in-phase carrier signal;
- means for modulating the other said ternary level encoded data character stream by a quadrature carrier signal;
- and
- means for summing said modulated carrier signals to produce a 3.times.3 QAM output signal;
- and
- receiver means comprising:
- means for splitting a received 3.times.3 QAM signal into in-phase and quadrature components;
- means for demodulating said in-phase and quadrature signal components to produce first and second streams of ternary encoded data characters;
- means for decoding said first and second streams of demodulated ternary data characters into respective streams of binary data bits;
- and
- means for combining said binary data bit streams to produce an output data bit stream representative of the information borne by said 3.times.3 QAM signal.
11 more elements
A method of modulating and demodulating an information bearing signal,
- the method of modulating the signal comprising the steps of:
- splitting a series of input binary data bits into two data bit streams;
- converting said binary data bit streams into respective streams of ternary level encoded data characters;
- modulating one of said ternary level encoded data character streams by an in-phase carrier signal;
- modulating the other said ternary level encoded data character stream by a quadrature carrier signal;
- and
- summing said modulated carrier signals to produce a 3.times.3 QAM output signal;
- and
- the method of demodulating the signal comprising the steps of:
- splitting a received 3.times.3 QAM signal into in-phase and quadrature components,
- demodulating said in-phase and quadrature signal components to produce first and second streams of ternary encoded data characters;
- decoding said first and second streams of demodulated ternary data characters into respective streams of binary data bits;
- and
- combining said binary data bit streams to produce an output data bit stream representative of the information borne by said 3.times.3 QAM signal.
11 more elements
Dependencies are inferred from the claim text.