Abstract: In a communications device, two coherent detection algorithms (102 and 103), one of which has a decision feedback equalizer (103), and a detector selection algorithm (104) are used to dynamically select a detector depending on whether delay spread distortion is present. First the correlation of the detector without the equalizer (102) is measured. If this correlation is greater than a predetermined threshold, the data from that detector (102) is used by the communications device. If the correlation is less than the threshold, the correlation of the detector with the equalizer (103) is measured. If this is less than the correlation of the detector without the equalizer (102), the data from the detector without the equalizer (102) is used, otherwise the data is taken from the equalizer (103). In any case, if the detector without the equalizer is used, the detector with the equalizer is turned off.

Abstract: In a receiver an apparatus and method substantially reduces time dispersion and multipath distortion in a received signal. An equalizer (109), including taps having gain coefficients, produces an equalized signal (110) responsive to the received signal (107) and an adaptive process signal (137), wherein the gain coefficients are adjusted responsive to the adaptive process signal (137). A first mixer (111) mixes the equalized signal (110) and a reference carrier signal (115) to produce a recovered modulated signal (119). A detector (112) detects an estimate signal (129) responsive to the recovered modulated signal (119). An error signal generator (139) generates an error signal (141) responsive to a difference between the recovered modulated signal (119) and the estimate signal (129). A second mixer (147) mixes the error signal (141) and the reference carrier signal (115) to produce the adaptive process signal (137).

Abstract: In a communications device, two coherent detection algorithms (102 and 103), one of which has a decision feedback equalizer (103), and a detector selection algorithm (104) are used to dynamically select a detector depending on whether delay spread distortion is present. First the correlation of the detector without the equalizer (102) is measured. If this correlation is greater than a predetermined threshold, the data from that detector (102) is used by the communications device. If the correlation is less than the threshold, the correlation of the detector with the equalizer (103) is measured. If this is less than the correlation of the detector without the equalizer (102), the data from the detector without the equalizer (102) is used, otherwise the data is taken from the equalizer (103).

Abstract: The .pi./4-QPSK coherent detector of the present invention has a vector input and an output comprising recovered data in bit pair form. The .pi./4-QPSK coherent detector recovers data that has been encoded in an amplitude modulated vector's phase angle. The .pi./4-QPSK coherent detector detects the .pi./4-QPSK constellation of the incoming modulated signal and outputs the recovered data stream.

Abstract: An antenna switch control circuit for use in achieving antenna selection diversity in TDM RF receivers. RSSI for at least one antenna is monitored during time slots containing information not of interest. This information can then be compared with other antenna performance information to allow a selection to be made such that the receiver generally operates with the antenna receiving the strongest signal. In one embodiment, all possible antennas are monitored during a time slot containing information not of interest. In another embodiment, RSSI for the selected antenna can be monitored during the time slot of interest, such that antenna selection can again be varied should the selected antenna diminish in performance.