Abstract: The preferred embodiment of the present invention is a communications apparatus which includes a first transmitting antenna array (15A) having a transmitting antenna (16) which is dedicated to serves only a first sector (12). Similarly, a second transmitting antenna array (17A) having a transmitting antenna (18) is dedicated to serve only a second sector (14). Each of the transmitting antenna arrays (15A, 17A) have a beamwidth (19) of generally less than fifteen degrees. Both the first and the second transmitting antenna arrays (15A, 17A) emanate shaped beams which are alternately polarized to ensure the isolation of beams that serve adjacent sectors.

Abstract: In a satellite communication system (10), a subscriber unit (26) is assigned a communication channel (17). The channel is used in the present cell (54) as well as subsequent cells (54) as the cells move relative to the earth. The channel is assigned using a cost function which includes a distance factor and an isolation factor. The distance factor which is based on a geographic distance between the nearest use of an interfering channel and the subscriber unit's cell. The isolation factor includes an interference potential between two channels. As a result of this channel assignment process, channels become associated with the geographic location of the subscriber unit. Accordingly, subscriber unit communications on the same satellite are handed-off between cells using the same channel making hand-offs invisible to the subscriber unit (26). When a hand-off is needed to another satellite, the same channel may also be used, or a new channel assigned using the cost function.

Abstract: A squelch circuit (111) that is contained in an communications receiver (100) estimates (403, 405) the energy of an input signal in an audio band and in a first portion of the audio band. The squelch circuit (111) then determines (407) whether the energy in the first portion of the audio band is at least a predetermined proportion of the total energy in the audio band. When the energy in the first portion of the audio band is at least a predetermined proportion of the total energy in the audio band, the squelch circuit increases (409) the audio band energy estimate to produce an updated audio energy estimate. The squelch circuit (111) can then use the updated audio energy estimate to adjust (413) a so-called squelch threshold that is subsequently used to determine (419) the presence of the radio frequency signal at an input (101) to the communications receiver (100).