Digital audio satellite transmission system
First Claim
1. A system for demodulating and processing a modulated intermediate frequency signal containing coded, combined digital audio and digital data signals comprising:
- (1) a binary phase shift key demodulator for demodulating the intermediate frequency signal into a data stream;
(2) a differential decoder for differentially decoding the data stream output by the demodulator;
(3) a bit deinterleaver for deinterleaving bits contained in the data stream output by the differential decoder;
(4) a forward error correction decoder for identifying partity bits in the data stream output by the bit deinterleaver;
(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.
1 Assignment
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Accused Products
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 or FEC decoding. The compressed digital signal is then expanded and converted to an analog audio signal.
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Citations
15 Claims
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1. A system for demodulating and processing a modulated intermediate frequency signal containing coded, combined digital audio and digital data signals comprising:
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(1) a binary phase shift key demodulator for demodulating the intermediate frequency signal into a data stream; (2) a differential decoder for differentially decoding the data stream output by the demodulator; (3) a bit deinterleaver for deinterleaving bits contained in the data stream output by the differential decoder; (4) a forward error correction decoder for identifying partity bits in the data stream output by the bit deinterleaver; (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. - View Dependent Claims (2, 12, 13, 14, 15)
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3. A system for demodulating and processing a modulated intermediate frequency signal containing coded, combined digital audio and digital data signals comprising:
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(1) a binary phase shift key demodulator for demodulating the intermediate frequency signal into a data stream; (2) a differential decoder for differentially decoding the data stream output by the demodulator; (3) a bit deinterleaver for deinterleaving bits contained in the data stream output by the differential decoder; (4) a forward error correction decoder for processing the data stream output by ythe bit deinterleaver to identify partity bits utilizing the convolutional self orthogonal code utilized in coding the signal; (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. - View Dependent Claims (4, 5, 6, 7)
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8. A method for receiving analog audio signals which were transmitted by:
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(a) converting the analog audio signals to digital form; (b) compressing the digital signals to reduce their data rates; (c) combining the compressed signals into a single data stream; (d) scrambling the data stream; (e) differentially encoding the scrambled data steam; (f) inverleaving the bits contained in the differentially encoded data stream; (g) forward error correction encoding the differentially encoded data stream utilizing a convolutional self orthogonal code; (h) binary phase shift key modulating an intermediate frequency carrier with the forward error correction coded data stream; (i) converting the modulated intermediate frequency signal to an earth-to-satellite transmission frequency; (j) amplifying the transmission frequency signal; (k) transmitting the amplified signal to a geosynchronous communication satellite with transponder; and (l) converting the signal received by the satellite to a satellite-to-earth transmission frequency and transmitting it to earth, comprising the steps of; (m) receiving the signal transmitted from the satellite and amplifying it; (n) converting the amplified received signal to the intermediate frequency; (o) demodulating the received intermediate frequency signal into a received data stream; (p) differentially decoding the received data stream; (q) bit deinterleaving the differentially decoded data stream; (r) idenfiying the forward error correction parity bits in the bit deinterleaved data stream utilizing the convolutional self orthogonal code utilized in encoding in the forward error correction encoding step; (s) descrambling the data stream from which the forward error correction parity bits have been stripped; (t) demultiplexing the descrambled data stream into separate data streams; (u) digitally expanding the demultiplexed data streams; and (v) converting the expanded digital data streams into analog audio signals. - View Dependent Claims (9)
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10. A method for receiving transmitted binary phase shift key modulated, partity bit forward error correction coded, bit interleaved, differentially encoded, scrambled, combined compressed, digitized analog audio signals comprising the steps of:
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(a) receiving the transmitted signal and amplifying it; (b) demodulating the received signal into a received data stream; (c) differentially decoding the received data stream; (d) bit deinterleaving the differentially decoded data stream; (e) identifying the forward error correction parity bits in the bit deinterleaved data stream; (f) descrambling the data stream from which the forward error correction parity bits have been stripped; (g) demultiplexing the descrambled data stream into separate data streams; (h) digitally expanding the demultiplexed data streams; and (i) converting the expanded digital data streams into analog audio signals. - View Dependent Claims (11)
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Specification