Telefonaktiebolaget Lm Ericsson (Publ)

Anders B Sandell

Tomas O Backstrom

Peter L Wahlstrom

A radio-frequency receiver employing antenna diversity is provided with a plurality of antennas and a local oscillator. Individual error signals are derived from each of respective ones of signals received from the plurality of antennas. The error signals are thereafter combined in such a way as to arrive at a combined error signal having greater reliability than any one of the individual error signals taken alone. Finally, an automatic frequency control circuit is controlled using the combined error signal. Since the effect of fading on the input signal to the automatic frequency control circuit is reduced, performance of the automatic frequency control circuit is increased and the quality of radio reception is improved.

Diversity radio receiver automatic frequency control

Synchronization is maintained between a regional radio transmitter/receiver and a remote transmitter/receiver communicating across a TDMA channel by detecting time misalignment of communications from the remote transmitter/receiver to the regional transmitter/receiver, commanding the remote transmitter/receiver to adjust its transmission timing, and, until the remote transmitter/receiver has adjusted its transmission timing, looking for a synchronization pattern accompanying transmissions by the remoter transmitter/receiver during two discontinuous time intervals, one centered about a time of occurrence of the synchronization pattern before the command and another centered about an expected time of occurrence of the synchronization pattern in response to the command. Effectively, what would otherwise be a disadvantageously wide time window is split into two advantageously narrow time windows to avoid detection of false syncs. Fewer false syncs are detected, and speech quality is increased.

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Upplands Vasby, Sweden

Anders B Sandell