Abstract: A method for implementing a timed division multiple access protocol for digital communications between a radio transceiver and a repeater or another radio transceiver has the steps of dividing a radio communication into a plurality of frames having a predetermined length of time; dividing each frame into: a plurality of downlink slots, each downlink slot containing a transmission from the repeater to the transceiver; and a plurality of uplink slots, each uplink slot containing a transmission from the transceiver to the repeater.

Abstract: A personal communications system has a plurality of personal communications units defining a network. The personal communications units are configured to send and receive digital communications among one another via the network. A wireless interface adaptor further defines the network and is configured to function as a repeater. The personal communications units are configured to cooperate with the wireless interface adaptor when the wireless interface adaptor is available. The wireless interface adaptor coordinates access of each personal communications unit to at least one other personal communications unit. The personal communications units are further configured to cooperate with one another to effect communications therebetween when no wireless interface adaptor is available.

Abstract: A personal communication system provides full duplex digital communications between multiple users for both audio and data. A universal adaptor interface receives a plurality of wireless communications. The wireless adaptor interface multiplexes the plurality of wireless communications into a composite signal. The universal adapter interface transmits the composite signal wirelessly. At least one personal communications unit receives the composite signal. Multiplexing the plurality of wireless communications facilitates simultaneous reception thereof by the personal communications units.

Abstract: A method for implementing a time division multiple access protocol for digital communications between a radio transceiver and a repeater or another radio transceiver has the steps of dividing a radio communication into a plurality of frames having a predetermined length of time; dividing each frame into: a plurality of downlink slots, each downlink slot containing a transmission from the repeater to the transceiver; and a plurality of uplink slots, each uplink slot containing a transmission from the transceiver to the repeater.

Abstract: A method for using a voice operated switch in a changing high noise environment involves determining a relative energy of the background noise, calculating VOX, voice, and delta thresholds, and comparing the VOX threshold to an amplitude of an incoming data sample. When the amplitude of the incoming data sample is greater than the VOX threshold, then the delta threshold is compared to the short-term average delta. When the amplitude of the short-term average delta is greater than delta threshold, then the voice threshold is compared to the short-term average. When the short term average is greater than the voice threshold, then the incoming data sample is determined to be voice and the voice operated switch is actuated.

Abstract: A method and a coarse tuning circuit for performing direct frequency selection and down-conversion on a received analog bandpass signal for a digital receiver having C channels are disclosed. Each of the C channels has a bandwidth B. The analog bandpass signal in a channel of interest has a center frequency f.sub.c and a two-sided bandwidth not greater than B. The method comprises the following steps: (a) sampling the bandpass signal at a sampling frequency f.sub.s greater than twice the product of B and C, to produce a digital sampled signal which has an intermediate frequency much closer to the baseband frequency of zero kilohertz than the sampling frequency f.sub.s ; (b) computing, from f.sub.c and f.sub.s, a non-negative integer value m to determine the selection of a channel from the C channels of the digital receiver; and (c) forming directly from the digital sampled signal two digital signals I.sub.1 and Q.sub.