Abstract: A radio communication system assigns one repeater the role of priority repeater, whereupon that priority repeater exclusively relays all messages between one or more portable radios and a base site. The priority repeater monitors various indica relating to its level of activity, and transitions to a non-priority state when the level of activity exceeds a prescribed threshold. In one embodiment, the repeater includes a counter for counting the number of transactions performed since the repeater was assigned the role of priority repeater, wherein the count serves as the activity level measure. In another embodiment, the repeater includes a timer for determining the amount of time which has transpired since the repeater assumed the role of priority repeater, wherein this time value serves as the activity measure. Still another embodiment uses battery level as a proxy for activity level. The above techniques may be employed in a non-trunked type of repeater or a trunked type of repeater.

Abstract: A base station is configured to facilitate its rapid deployment to provide trunked radio communication system. The base station includes a receiving section and a transmitting section functioning as a repeater operating on a single trunked duplex channel. The base station also includes another receiving section for interrogating the presence of pre-existing RF energy in a given geographic area before allowing the base station to become active. This prevents a newly introduced deployable base station from interfering with pre-existing deployable or fixed base stations.

Abstract: A battery-powered portable radio conserves battery power while the radio monitors messages transmitted over a radio channel, e.g., a radio control channel, Message processing circuitry processes a detected message and stores that message in memory. Before processing a subsequently detected message, the subsequent message is compared with the stored message. It they do not match, the subsequently detected message is subjected to further processing including voting, matching, validity, checking, etc. However, if they match, the subsequent message is ignored as a redundant message and a power savings mode is entered to conserve battery power.

Abstract: A vehicular repeater system communicates with a portable mobile radio using the same RF communication band and digital trunking protocol that it communicates with a base site. The repeater station may employ an operational radio within a vehicle which communicates with the base site. A separate repeater radio module is connected to the operational radio, preferably through hardwired links. The separate repeater radio module includes a transmitting section which receives messages from the base site through the operational radio, and forwards these messages through a passive RF interface to a portable radio. The separate repeater also includes a receiving section which receives messages from the portable radio, and forwards these messages through the operational radio to the base site.

Abstract: A base station-based communications system provides radio communication with battery-operated, portable radios, each radio including predetermined radio operating parameters corresponding to particular radio operating conditions. Each portable radio determines for itself one or more current radio operating condition(s), and based thereon, adjusts one or more radio operating parameters.

Abstract: A base station-based communications system provides radio communication with battery-operated, portable radios, each radio including predetermined radio operating parameters corresponding to particular radio operating conditions. Each portable radio determines for itself one or more current radio operating condition(s), and based thereon, adjusts one or more radio operating parameters.

Abstract: A base station-based communications system provides radio communication with battery-operated, portable radios, each radio including predetermined radio operating parameters corresponding to particular radio operating conditions. Each portable radio determines for itself one or more current radio operating condition(s), and based thereon, adjusts one or more radio operating parameters.

Abstract: A digital radio has standardized "key" storage for several different cryptosystems (DES, VGE, VGS, etc.). Cryptographic keys are stored in a table in non-volatile memory such as EEPROM. The "keys" are stored in an "encrypted" form such that their identities are not readily revealed by a "dump" of memory contents. Additional security is provided in accordance with the present invention by extracting the "keys" from the stored table and re-"encrypting" the entire table each time a key loader device is attached to the radio. Multiple key banks are used to provide enhanced voice security by increasing the number of encryption keys available for use by a radio.