Digital encoder-decoder
First Claim
1. In a data communications system for the transmission and reception of a data bit stream, the improvement comprising:
- an encoder for receiving information and processing said information into the data bit stream to be transmitted, said encoder comprising;
cyclic block encoder means for receiving information and producing an error detectable encoded bit stream corresponding thereto;
encoder storage means having a predetermined autosynchronization sequence stored therein;
said autosynchronization sequence selected to optimize, at a decoder, the generation of errors during an out-of-synchronization condition to enable determination of out-of-synchronization conditions between said encoder and decoder;
encoder combining means for combining said autosynchronization bits from the encoder storage means with the bit stream from said cyclic block encoder means to produce a concatenated bit stream; and
convolutional encoder means for receiving said concatenated bit stream from the encoder combining means and producing an error correctable encoded data bit stream corresponding thereto; and
a decoder for receiving and processing said data bit stream to recover said information, said decoder comprising;
convolutional decoder means for receiving said data bit stream and producing an error corrected bit stream;
decoder storage means having a predetermined sequence of autosynchronization bits stored therein, the predetermined sequence of autosynchronization bits corresponding to the autosynchronization bits stored in said encoder storage means;
decoder combining means for combining said error corrected bit stream from the convolutional decoder means with said autosynchronization bit sequence from the decoder storage means and to provide a block encoded bit stream; and
cyclic block decoder means for decoding said block encoded bit stream to recover said information, said cyclic block decoder means further producing an output indicating the presence of errors in the recovered data bit stream when said decoder is in synchronization with said encoder.
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Abstract
A digital encoding and decoding system suited for use in a mobile trunked dispatch communication system capable of error correction, error detection, and detection of loss of synchronization. The encoder comprises a cyclic block encoder, an autosynchronization sequence combiner, a convolutional encoder, and a bit interleaver to encode information to be transmitted. The decoder comprises a bit de-interleaver, a convolutional decoder, an autosynchronization sequence combiner, and a cyclical block decoder to recover the transmitted information and also indicates whether any errors are present in the recovered information.
108 Citations
10 Claims
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1. In a data communications system for the transmission and reception of a data bit stream, the improvement comprising:
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an encoder for receiving information and processing said information into the data bit stream to be transmitted, said encoder comprising; cyclic block encoder means for receiving information and producing an error detectable encoded bit stream corresponding thereto; encoder storage means having a predetermined autosynchronization sequence stored therein;
said autosynchronization sequence selected to optimize, at a decoder, the generation of errors during an out-of-synchronization condition to enable determination of out-of-synchronization conditions between said encoder and decoder;encoder combining means for combining said autosynchronization bits from the encoder storage means with the bit stream from said cyclic block encoder means to produce a concatenated bit stream; and convolutional encoder means for receiving said concatenated bit stream from the encoder combining means and producing an error correctable encoded data bit stream corresponding thereto; and a decoder for receiving and processing said data bit stream to recover said information, said decoder comprising; convolutional decoder means for receiving said data bit stream and producing an error corrected bit stream; decoder storage means having a predetermined sequence of autosynchronization bits stored therein, the predetermined sequence of autosynchronization bits corresponding to the autosynchronization bits stored in said encoder storage means; decoder combining means for combining said error corrected bit stream from the convolutional decoder means with said autosynchronization bit sequence from the decoder storage means and to provide a block encoded bit stream; and cyclic block decoder means for decoding said block encoded bit stream to recover said information, said cyclic block decoder means further producing an output indicating the presence of errors in the recovered data bit stream when said decoder is in synchronization with said encoder. - View Dependent Claims (2, 3)
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4. A method for enhancing the transmission and reception of data in a digital communications system comprising the steps of encoding a data bit stream by:
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error detection encoding said data bit stream with a cyclic block encoder to produce an error detectable bit stream; combining a predetermined sequence of autosynchronization bits, selected to optimize the generation of errors detected in an error detection decoding step for an out-of-synchronization condition, with said error detectable bit stream, thereby producing a concatenated bit stream; error correction encoding said concatenated bit stream with a convolutional encoder to produce an error correctable encoded bit stream; and decoding said bit stream by; decoding the convolutional encoding of said bit stream with a convolutional decoder to correct errors and produce an error corrected bit stream; combining a predetermined sequence of autosynchronization bits, corresponding to the sequence of autosynchronization bits used by the encoder with said error corrected bit stream, to produce a block encoded signal having decodable cyclic block codes; and decoding the cyclic block encoding of said error corrected bit stream with a cyclic block decoder to detect errors and produce a decoded data bit stream and an error detect signal when the encoding steps at the encoder are in synchronization with the decoding steps at the decoder. - View Dependent Claims (5, 6)
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7. In a trunked dispatch system for mobile radio communication using a digital control channel between an encoder for encoding data for transmission on said digital control channel of said trunked dispatch system, and a decoder for receiving and processing the encoded data transmitted on said control channel to recover the data, said encoder comprising:
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cyclic block encoder means for receiving the data for transmission on said digital control channel and producing an error detectable cyclic block code corresponding thereto; storage means for having an autosynchronization frame stored therein, said autosynchronization frame selected to optimize the generation of errors at the decoder caused by an out-of-synchronization condition between said encoder and decoder; modulo-2 adder means for performing a bit-by-bit exclusive-OR of said error detectable block code and said autosynchronization frame and producing a modulo-2 sum; rate one-half convolutional encoder means for encoding the modulo-2 sum and producing a bit sequence including the modulo-2 sum bits, a flush-out bit, and parity bits; and bit interleaving means for reordering the bits in the output of said convolutional encoder to produce an interleaved bit sequence. - View Dependent Claims (8)
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9. In a trunked dispatch system for a mobile radio communication using a digital control channel between an encoder for encoding data for transmission on said digital control channel and a decoder for receiving and processing the data transmitted on said control channel to recover the data, the decoder comprising;
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de-interleaving means for receiving said encoded data and producing an error correctable bit sequence; rate one-half convolutional decoder means for decoding said error correctable bit sequence and producing an error corrected bit sequence; storage means for having an autosynchronization frame stored therein; modulo-2 adder means for performing a bit-by-bit exclusive-OR of said error corrected bit sequence and the stored autosynchronization frame to produce a decoded modulo-2 sum; and cyclic block decider means for receiving said decoded modulo-2 sum and producing decoded data bits and an error detect signal. - View Dependent Claims (10)
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Specification