QAM detector which compensates for received symbol distortion induced by a cellular base station

摘要: A cellular subscriber modem for receiving CCITT-type quadrature amplitude modulated (QAM) signals. The includes a novel symbol detector that converts received information to polar notation. detector's constellation thresholds include circular threshold having radius greater than the magnitude of innermost symbols, but less outermost and radially spaced thresholds, which further discriminate between symbols. As result, special cellular-compatible equipment need not be connected public-access switched telephone network computer at other end, means CCITT-compatible can then treated as any type CCITT-modem. may implemented in software standard processor, or several analog comparator circuits.