Abstract: A data communications system is described that covers a geographic area divided into a plurality of non-overlapping zones and includes a general communications controller (GCC), a plurality of channel communications modules (CCM) and associated transmitters and receivers, and a plurality of portable radios. Message signals carrying alphanumeric information are communicated between the GCC and the portable radios by way of a radio channel. Each CCM takes a signal strength measurement every time it receives a message signal from a portable radio. The GCC gathers the signal strength measurements from the CCM receivers receiving the same message signal and computes an adjusted signal strength for each zone. The GCC then selects the zone having the largest adjusted signal strength for determining the location of the portable radio that transmitted the message signal.

Abstract: A data communications system is described that covers a geographic area divided into a plurality of non-overlapping zones and includes a general communications controller (GCC), a plurality of channel communications modules (CCM) and associated transmitters and receivers, and a plurality of portable radios. Message signals carrying alphanumeric information are communicated between the GCC and the portable radios by way of a radio channel. Each CCM takes a signal strength measurement every time it receives a message signal from a portable radio. The GCC gathers the signal strength measurements from the CCM receivers receiving the same message signal and computes an adjusted signal strength for each zone. The GCC then selects the zone having the largest adjusted signal strength for determining the location of the portable radio that transmitted the message signal.

Abstract: A data communications system is described in which variable length messages are communicated between a general communications controller (GCC) and a plurality of portable and mobile radios. The variable length messages include a bit synchronization field, a message synchronization field and a plurality of channel data blocks for efficiently and reliably handling long strings of data or text. Each channel data block includes an information field, a parity field for error-connecting the information field and a channel state field indicating whether or not the radio channel is busy or free. The GCC is coupled to a cellular arrangement of channel communications modules (CCM's), which each include a radio transmitter and/or radio receiver. The mobile and portable radios communicate with the GCC by way of the CCM's.

Abstract: A data communications system is described in which variable length messages are communicated between a general communications controller (GCC) and a plurality of portable and mobile radios. The variable length messages include a bit synchronization field, a message synchronization field and a plurality of channel data blocks for efficiently and reliably handling long strings of data or text. Each channel data block includes an information field, a parity field for error-connecting the information field and a channel state field indicating whether or not the radio channel is busy or free. The GCC is coupled to a cellular arrangement of channel communications modules (CCM's), which each include a radio transmitter and/or radio receiver. The mobile and portable radios communicate with the GCC by way of the CCM's.

Abstract: A data communications system is described that covers a geographic area divided into a plurality of non-overlapping zones and includes a general communications controller (GCC), a plurality of channel communications modules (CCM) and associated transmitters and receivers, and a plurality of portable radios. Message signals carrying alphanumeric information are communicated between the GCC and the portable radios by way of a radio channel. Each CCM takes a signal strength measurement every time it receives a message signal from a portable radio. The GCC gathers the signal strength measurements from the CCM receivers receiving the same message signal and computes an adjusted signal strength for each zone. The GCC then selects the zone having the largest adjusted signal strength for determining the location of the portable radio that transmitted the message signal.

Abstract: Data muting apparatus is described that mutes variable-length data signals communicated between a central station and mobile and portable radios in a dispatch radio communications system. The central station includes a base station transceiver, a dispatcher console, a general communications controller (GCC), a digital communications computer and a display terminal. The base station transmitter and receiver communicate over an RF duplex channel to the transceiver of the mobile and portable radios. The dispatcher console provides for voice communications and is coupled by a transmit signal line and a receive signal line to the base station transceiver. The GCC provides for data communications and is also coupled to the transmit signal line and is interposed between the dispatcher console and the base station transceiver in the receive signal line. The GCC and mobile and portable radios include data muting apparatus enbodying the present invention.

Abstract: A mobile data terminal system is capable of voice or microprocessor controlled data transmission over a keyed transmitter. The improved timer apparatus disables further transmission if the transmission duration or the average duty cycle over a predetermined time period of repeated transmitter keying exceed predetermined limits. Where the disable mode resulted from a microprocessor fault, the transmitter continues to be disabled until the microprocessor is reset.

Abstract: In a control circuitry for a two-way mobile radio voice/data shared communications system including a plurality of mobile stations with data and voice terminals, a base station, a dispatching station for voice and data, a voice/data processor interposed between the voice/data dispatching station and the base station, there is provided means for enabling transmission and reception of inbound and outbound voice and digital data signals between the base station and the mobile stations selectively to effect full-duplex voice/data shared communications.