Abstract: A method and apparatus diversity-combine radio signals received from a plurality of branches (108, 214). Each radio signal comprises a plurality of subchannels (806). The radio signal from each branch (108, 214) is digitized (904) into digital samples that are converted (908, 910) into frequency domain signals (702, 712). Each frequency domain signal (702, 712) corresponds to a subchannel and a branch (108, 214). A weighting factor is determined (916) for each branch (108, 214) and each subchannel (806) from instantaneous signal energy and noise power calculated (912, 914) from the frequency domain signals (702, 712). The frequency domain signal (702, 712) corresponding to each branch (108, 214) and each subchannel (806) is multiplied (918) by the weighting factor therefor to produce weighted frequency domain signals corredponding to each branch and each subchannel.

Abstract: A frequency shift keyed receiver (214, 220, 218) estimates a carrier frequency and demodulates (1020) a symbol value associated with the carrier frequency. During symbol intervals, the receiver (214, 220, 218) receives a radio signal including symbol values (502-518) corresponding to predetermined frequency offsets (604, 606) from a carrier frequency. The radio signal is digitized (1008) during a symbol interval, and then converted (1010) into a frequency domain signal. The frequency domain signal is stored (1012), and additional symbol intervals are converted to obtain a plurality of frequency domain signals, which are processed to generate (1016) a composite frequency domain signal (702, 704). A windowing function (706) of predetermined shape is convolved (1018) with the composite frequency domain signal (702, 704) to locate a frequency distribution therein that corresponds to the predetermined frequency offsets (604, 606).

Abstract: Power consumption in a portable communication unit (101) is reduced by first transmitting at a first time, a message (701) at a first transmit power level to a repeater (103) on a first communication channel. At a second time the message (701) is repeated (903) by the repeater on a second communication channel, thereby transmitting a delayed message (703). The portable communication unit (101) tunes (807) to the second communication channel after transmitting all of the message (701), so as to receive at least part of the delayed message (703). The repeater (103) establishes a receive quality metric (705) for the message (701) and transmits (909) the receive quality metric after all of the delayed message (703) is transmitted. The portable communication unit receives and stores (809) the receive quality metric (705), and determines a second transmit power level for transmitting another message using the receive quality metric.