Abstract: A spread spectrum radio frequency communication system comprising a plurality of transmitters adapted to operate at different carrier frequencies having a preassigned frequency separation, such carrier frequencies randomly changing in accordance with a common pseudo-random code. Each of the transmitters has a predetermined bandwidth and the carrier frequencies of the transmitters are in accordance with the bandwidth of the transmitters.

Abstract: A half-duplex digitally-controlled telephone communication apparatus for permitting half-duplex communication between local and remote subscribers. Analog speech of one subscriber to be transmitted to the other subscriber is converted to a digital format, processed by real-time speech processing apparatus, stored in a delay buffer, and processed in modem apparatus for transmission to the other subscriber. In accordance with the present invention, the delay buffer provides a delay of a sufficient duration to compensate for inherent delays in the system in detecting the presence (or absence) of speech signals and serves to prevent the loss to the remote subscriber of portions of speech of the local subscriber, especially the onset of speech or rapid utterances of the local subscriber.