Abstract: An improved duplex time division multiplexed (TDM) communication system is provided while conserving spectrum and efficiency. To accommodate two voice signals on one channel, the time allocated in a channel for brief listener voice acknowledgements is short; the time allocated for talker transmission is long. Moreover, the coding rate for the listener is slower than for the talker. The slot allocation can be switched whereby whoever is the dominant talker will maintain the longer slot.

Abstract: A two-way radio includes a receiver having a squelch circuit and a selective calling decoder. A transmitter is connected to an inhibit circuit. The inhibit circuit is responsive to the selective calling decoder for permitting transmission after reception of the radio's ID code. The inhibit circuit inhibits further transmissions if the squelch circuit indicates loss of carrier for more than a predetermined time during receive.

Abstract: A signalling and control protocol is provided wherein each subscriber unit (106) operating within a communication system (100) must transmit a request (200, 200' or 200") to communicate to a central station. If a communication channel is available, the central station returns a channel grant (210), which includes a time code representing a time duration during which the requesting subscriber may communicate. After receiving the channel grant (210), the subscriber unit may communicate for a time interval not exceeding the time duration, and, immediately prior to the expiration of the time duration, the subscriber unit may itself provide a warning tone indicating the impending loss of the communication channel. Conversely, if a communication channel is not available, the central station provides a busy message (216), which includes a code (218) representing the requesting subscriber unit's position is a call request queue.

Abstract: A radio communication system includes a base station and a plurality of remote units. The remote units can be operated in one of several modes. In the Message Storage mode, a telephone or remote unit caller is verbally informed that the called remote unit is not receiving calls, and the caller is then given the option to store a voice or numeric message for later transmission to the called remote unit. If a caller enters an Override code, however, the system attempts to establish voice communication between the caller and the called remote unit. In the Call Screening mode, the caller's message is stored in the base station and, simultaneously, forwarded to the called remote unit. During reception of the message, the called remote unit can "pickup" the call and begin normal voice communications with the caller. When a remote unit changes from the Message Storage mode to some other mode, its stored messages are automatically forwarded to the remote unit.

Abstract: A stretchable, flexible cargo strap assembly comprises an elongated, stretchable first member having the properties of generating restoring force when stretched from a relaxed condition to a tensioned condition, and an elongated second member having a portion which coextends with at least a portion of the first member. The second member is secured to the first member by a plurality of securing members distributed at two or more longitudinally spaced locations along the coextending portions of the first and second members and intermediate the ends of said members, for substantially inhibiting or limiting relative longitudinal movement of the first and second members at these locations while providing for such movement between these locations. The second member is extendable, by stretching of the assembly, to an extended position in which the end-to-end distance of the second member is at least about 1.