US 4,567,591 A · Digital audio satellite transmission system

Abstract

A digital audio satellite transmission system involving analog-to-digital conversion of audio signals, processing of such signals and transmission to and reception from a satellite transponder link. The digitized audio signal is digitally compressed to reduce the data rate. Several such signals are then time division multiplexed together. Differential encoding, bit interleaving and forward error correction coding is utilized to maintain high signal quality, together with binary phase shift key carrier modulation. Matched filter reception of the BPSK signal transmitted over a conventional satellite transponder link is provided together with BPSK demodulation, TDM demultiplexing, differential decoding, bit deinterleaving and threshold FEC decoding. The compressed digital signal is then expanded and converted to an analog audio signal.

Claims15

Dependent claims

A system for processing analog audio and digital data signals and modulating an intermediate frequency carrier for subsequent conversion to a transmission frequency, amplification and transmission comprising:

(1) a source encoder for converting the analog audio portions of said signals to digital form;
(2) a digital compressor for compressing the digitized analog audio signals to reduce their data rates;
(3) a multiplexer for combining into a single data stream the compressed signals output by the compressor;
(4) a forward error correction encoder for encoding the data stream output by the multiplexer utilizing a convolutional self orthogonal code;
(5) a bit interleaver for interleaving the bits contained in the data stream output by the forward error correction encoder;
(6) a differential encoder for differentially encoding the data stream output by the bit interleaver;
and
(7) a binary phase shift key modulator for modulating the data stream output by the differential encoder at an intermediate frequency.

5 more elements

A system for transmission and reception of analog audio and digital data signals comprising:

(a) a signal processing and modulation subsystem comprising:
(1) a source encoder for converting the analog audio portions of said signals to digital form;
(2) a digital compressor for compressing the digitized analog audio signals to reduce their data rates;
(3) a multiplexer for combining into a single data stream the compressed signals output by the compressor;
(4) a differential encoder for diferentially encoding the data stream output by the multiplexer;
(5) a bit interleaver for interleaving the bits contained in the data stream output by the differential encoder;
(6) a forward error correction encoder for encoding the data stream output by the bit interleaver utilizing a convolutional self orthogonal code;
and
(7) a binary phase shift key modulator for modulating the data stream output by the forward error correction encoder at an intermediate frequency;
(b) a frequency conversion, amplification and transmission subsystem comprising:
(1) an up-converter for converting the modulated intermediate frequency signal output by the modulator to an earth-to-satellite transmission frequency;
(2) an amplifier for amplifying the signal output by the up-converter;
and
(3) an antenna for transmitting the amplified signal output by the up-converter;
(c) a geosynchronous communication satellite with transponder for receiving the signal transmitted by the transmission antenna, converting it to a satellite-to-earth transmission frequency and transmitting it to earth;
(d) a reception, amplification and frequency conversion subsystem comprising:
(1) a receiving antenna for receiving the signal from the communication satellite;
(2) a low noise amplifier for amplifying the received signal;
and
(3) a down-converter for converting the signal output by the low noise amplifier to the intermediate frequency;
and
(4) a forward error correction decoder for decoding the data stream output by the bit deinterleaver to identify transmission errors utilizing the convolutional self orthogonal code utilized in the forward error correction encoder;
(5) a demultiplexer for dividing into separate data streams the single data stream output by the forward error correction decoder;
(6) a digital expander for expanding the digitized audio signals output by the demultiplexer;
and
(7) a source decoder for converting the digitized analog audio portions of the signals output by the digital expander to analog form.

23 more elements

Dependencies are inferred from the claim text.

Digital audio satellite transmission system

Life of this patent

Digital audio satellite transmission system

Life of this patent

Abstract

Claims15