US 5,168,509 A · Quadrature amplitude modulation communication system with transparent error correction

Abstract

In a multi-level QAM communication system, Reed-Solomon encoders and Reed-Solomon decoders are employed for error correction purposes. The phase ambiguity of the received signal is eliminated with differential coding. The multi-level QAM communication system utilizing n bits ("n" being an integer) QAM signal having 2.sup.n signal points, comprises: a quadrature differential encoder/decoder unit for differentially encoding/decoding n pieces of input digital signal series to produce n pieces of differentially coded signal series; an error correction unit including a Reed-Solomon encoder and a Reed-Solomon decoder, provided inside the quadrature differential encoder/decoder unit along a signal processing path of the input digital signal series, for error-correcting the n pieces of differentially-coded signal series by utilizing at least one of the digital signal series with employment of a Reed-Solomon code; and, a QAM modulator/demodulator unit for QAM-modulating/demodulating n pieces of error-corrected signal series so as to produce 2.sup.n QAM signals.

Claims16

Dependent claims

A multi-level QAM (quadrature amplitude modulation) communication system having signal processing path and utilizing an n bits ("n" being an integer) QAM signal having 2.sup.n signal points, comprising:

differential encoder/decoder means, located along said signal processing path, for differentially encoding/decoding n pieces of an input digital signal series to resolve phase ambiguity contained in a differentially encoded input signal series;
error correction means including a Reed-Solomon encoder and a Reed-Solomon decoder, provided inside said differential encoder/decoder means along said signal processing path for said input digital signal series, for error-control-encoding/decoding n pieces of said differentially encoded input signal series by utilizing at least one of said digital signal series to correct errors by employment of Reed-Solomon codes;
and
QAM modulator/demodulator means, located along said signal processing path, for QAM-modulating/demodulating n pieces of error-control-encoded signals series so as to produce 2.sup.n QAM signals.

1 more element

A multi-level QAM (quadrature amplitude modulation) communication system having a signal processing path and for producing an n bits ("n" being an integer) QAM signal having 2.sup.n signal points from n pieces of an input digital signal series, comprising:

differential encoder/decoder means, located along said signal processing path, for differentially encoding/decoding at least two pieces of said input digital signal series for determining a quadrant of a phase plane for a signal point mapping among said n pieces of said input digital signal series so as to produce at least two pieces of differentially-encoded signal series;
first error correction means, provided inside said differential encoder-decoder means and located along said signal processing path for said input digital signal series, for error correction so as to produce at least two pieces of first error-control-encoded signal series;
second error correction means, located along said signal processing path, provided directly to receive remaining pieces of said input digital signal series so as to produce a second error-control-encoded signal series;
and,
QAM modulator/demodulator means, located along said signal processing path, for QAM-modulating/demodulating both said first error-control-encoded signal series and second error-control-encoded signal series so as to output said n bits QAM signal, whereby phase ambiguity contained in said differentially-encoded signal series is solved.

2 more elements

Dependencies are inferred from the claim text.

Quadrature amplitude modulation communication system with transparent error correction

Life of this patent

Quadrature amplitude modulation communication system with transparent error correction

Life of this patent

Abstract

Claims16