Analog Devices,inc.

Suraj Sreekanta

Nilesh Bhattad

An error correction method corrects and replaces erroneous digital signal samples (having N companded bits) in a receiver after ascertaining by parity check that a sample is erroneous. The method chooses M MSBs where M is less than or equal to N, and produces M test samples, each test sample being obtained by inverting a single bit from the M bits, keeping other bits unaltered. Each test sample is expanded and passed through a selected low pass filter (e.g., 15 kHz) to obtain a filtered output and a differential value between the test sample and its filtered output. The test sample producing the least differential value is chosen to replace the erroneous signal sample. The technique is applicable in NICAM demodulators receiving 14 bit sample signals (at 32 kHz) companded to (N) 10 bits from which (M) 6 MSB parity encoded bits are chosen for producing test samples.

Parity error correction for band-limited digital signals

An error correction method corrects and replaces erroneous digital signal samples (having N companded bits) in a receiver after ascertaining by parity check that a sample is erroneous. The method chooses M MSBs where M is less than or equal to N, and produces M test samples, each of the M test samples being obtained by inverting a single bit from the M bits, keeping other bits unaltered. Each test sample is expanded and passed through a selected low pass filter (e.g., 15 kHz) to obtain a filtered output and a differential value between the test sample and its filtered output. The test sample producing the least differential value is chosen to replace the erroneous signal sample. The technique is especially applicable in NICAM demodulators receiving 14 bit sample signals (at 32 kHz) companded to (N) 10 bits from which (M) 6 MSB parity encoded bits are chosen for producing test samples.

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Suraj Sreekanta