Patent ID: 6421388
Filing Date: 2002-07-16
Classification: H04B

Abstract:
A method of determining decision regions in a communication receiver connected to a digital telephone network by an analog loop comprising the steps of:obtaining samples of a received signal voltage from a digital network, the samples representing a sequence of PCM codewords; determining at least one decision region within a reference lattice in response to at least one sample; quantizing the samples to a nearest valid PCM codeword using said at least one decision region within the reference lattice; calculating quantizer error by comparing the samples to the quantized samples; adjusting the reference lattice; adjusting said at least one decision region within the adjusted decision lattice; re-quantizing the samples using the adjusted reference lattice; re-calculating quantizer error by comparing the samples to the re-quantized samples; and selecting a final reference lattice for use in the receiver in response to the calculated and re-calculated quantizer error thereafter, quantizing all received samples using the final reference lattice.