Error correction of digital signals
First Claim
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1. A method of correcting errors in a digital signal, the method comprising the steps of:
- receiving a digital signal comprising information bits, first error control bits corresponding to a first error control code, and second error control bits corresponding to a second error control code,decoding the first error control bits to determine the probability of error in the received signal,decoding the second error control bits,using the error probability determined from the first error control bits to define a correction algorithm, andcorrecting the information bits by performing on them the said correction algorithm using the decoded second error control bits.
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Abstract
Data bits are combined at a transmitter with parity check code bits and convolutional check code bits. On reception the parity check code bits are decoded to determine the error probability in the received signal. The convolutional check code bits are used to correct the received data according to a correction algorithm which is defined in dependence on the error probability revealed by the parity check code bits. The received data is divided into bytes and each byte is given a respective error probability rating. Circuitry including logic gates and shift registers are used to carry out the encoding, decoding and correction operations.
36 Citations
25 Claims
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1. A method of correcting errors in a digital signal, the method comprising the steps of:
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receiving a digital signal comprising information bits, first error control bits corresponding to a first error control code, and second error control bits corresponding to a second error control code, decoding the first error control bits to determine the probability of error in the received signal, decoding the second error control bits, using the error probability determined from the first error control bits to define a correction algorithm, and correcting the information bits by performing on them the said correction algorithm using the decoded second error control bits. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. Apparatus for correcting errors in a digital signal, the apparatus comprising:
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input means to receive a digital signal comprising information bits, first error control bits corresponding to a first error control code, and second error control bits corresponding to a second error control code, first decoding means connected to the input means to decode the first error control bits to determine the probability of error in the received signal, second decoding means connected to the input means to decode the second error control bits, algorithm -- defining means connected to the output of the first decoding means to define a correction algorithm using the error probability determined from the first error control bits, and correction means connected to the algorithm-defining means, the second decoding means and the input means to correct the information bits by performing on them the said correction algorithm using the decoded second error control bits. - View Dependent Claims (11, 12, 13, 14, 15, 16)
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17. A data transmission system comprising in combination
a. a transmitter including encoding apparatus for coding a digital signal for error correction on reception comprising: -
transmitter input means to receive information bits to be trasmitted, first error control bit inserting means connected to said transmitter input means to add to the information bits first error control bits corresponding to a first error control code and decodable on reception to determine the probability of error in the received signal, second error control bit inserting means connected to said transmitter input means to add to the information bits second error control bits corresponding to a second error control code and decodable on reception so that a correction algorithm defined in accordance with the error probability determined from the first error control bits can be performed on the information bits using the decoded second error control bits, and output means connected to the outputs of the first and second error control bit inserting means, and b. a receiver including correcting apparatus for correcting errors in the coded digital signal, the correcting apparatus comprising; signal input means connected to receive the coded digital signal first decoding means connected to the signal input means to decode the first error control bits to determine the probability of error in the received signal, second decoding means connected to the signal input means to decode the second error control bits, algorithm-defining means connected to the output of the first decoding means to define a correction algorithm using the error probability determined from the first error control bits, and correction means connected to the algorithm-defining means, the second decoding means and the input means to correct the information bits by performing on them the said correction algorithm using the decoded second error control bits. - View Dependent Claims (18, 19, 20, 21, 22, 23, 24, 25)
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Specification