Abstract: Shown, herein, is a method of allowing use of small, low-power communication systems within the service coverage area of larger trunked systems. The small, low-power systems are constructed to reuse at least some of the inbound frequencies of communication resources, also used by the larger system. The large system measures signal strength values of large cell communication units and transfers such values to the small systems. A small system also measures the signal strength and compares the measured and transferred values with thresholds and when the thresholds are exceeded, reuses the communication resources under a TDM format within the small system.

Abstract: A way of allowing small, low-power communication units to reuse trunked system communication resources within the service coverage area of the larger trunked system without experiencing significant interference from the trunked system. The low power units (requestors and targets) avoid interference through spread spectrum transmissions.

Abstract: In a geographic region that contains a trunking communication system and a cellular communication system, where the coverage area of each system substantially overlaps, a method that enables a communication unit to operate in either system is disclosed. Normally in accordance with the present invention, a communication unit will monitor a control channel of the cellular communication system. When the communication unit is needed within the trunking communication system, a communication channel controller of the trunking communication system will place a telephone call to the communication unit via the cellular communication system. The telephone call indicates to the communication unit that it should transfer its affiliation from the cellular communication system to the trunking communication system. Once the communication unit has transferred its affiliation to the trunking communication system, it operates as a trunking communication unit.

Abstract: Independent communication systems are provided with additional receivers that allow the systems to monitor one another's outbound control signalling channels. Secondary control signalling can be interleaved with the primary control signalling information on this communication resource, which secondary control signalling information is intended for reception and use by the monitoring system.

Abstract: A communication system supporting dispatch-like communications in a geographic reuse system environment. An originating user provides a verbal alias corresponding to a target communication unit. The system utilizes the verbal alias to locate a corresponding system identification code for the target unit. The system then determines the general whereabouts of the target unit, and establishes a communication path between the two units. The original voice message may be stored and subsequently transmitted to the target unit upon properly identifying, locating, and establishing a communication path to the target unit.

Abstract: A personal identity authentification system is provided in which parametric data of an authorized possessor is encrypted into a memory of a portable transceiver device. The portable transceiver device, carried by a possessor, may be activated by an identity request transmitted from a nearby, authorized verification device. Upon activation, the portable transceiver transmits the encrypted data to the verification device which, when decoded by a verification unit, provides positive identification of the authorized possessor.

Abstract: Communication systems having dedicated communication resources are provided with receivers that monitor the communication resources of other communication systems, and roamers are preregistered in non-home systems. Using this infrastructure, a group call can be sourced in one system and relayed to roamers located in other systems.

Abstract: A trunked communication system wherein less than all of the communication units may transmit an identifying data word thereby registering their location to a system controller every time they enter a different coverage area, while the remainder of the communication units do not. The identity of the communication units which operate in each mode is known to the system resource controller in advance. Pre-registration allows the system controller to know the locale of target units in advance when communications to those units is requested. The locale of units that do no pre-register their location are identified through system wide paging. Coordinating the identification of locales of units in both modes permits greater optimization of spectral resources.

Abstract: Reusing radio frequency specta in a trunked radio system by establishing small cell trunked radio systems within a large cell trunked radio system wherein low power radio transmission occurs permits multiple small cell trunked radio systems in geographically separate locatiosn to use a limited number of radio resources simultaneously, increasing usage of a finite number of communication resources. As used in cellular telephone systems, very low power trunked radio systems separated from each other can reuse the same frequency without interfering with each other or interfering with a large cell trunked radio system license holder.

Abstract: An improved communication system is disclosed wherein at least one reprogramming station is added to a communication system. The reprogramming station is constructed and arranged to communicate with the subscriber units thereby either reprogramming or regrouping them. The subscribing units receive the reprogramming command and acknowledge individually, altering a memory means until either reprogrammed back to the original state, or to another state. In another mode, the reprogramming station transmits a regrouping command wherein two or more groups are combined to form a super group.

Abstract: A computer aided dispatch system is provided for use in a trunked communication system. The system comprises at least a master file node and a plurality of user nodes. The master file node contains a data record for each subscriber on the trunked communication system. Each data record has a plurality of fields that may assume various values. Each dispatcher "attaches" to a particular value of at least one field in any of the data records. The master file node maintains the records for each subscriber and automatically transmits an updated record to each dispatcher attached to the subgroup in which the subscriber operates. In this way, dispatchers are continuously provided the latest subscriber status even though the responsibility for monitoring the status of a particular subscriber unit may dynamically pass from dispatcher to dispatcher.

Abstract: Disclosed is a method to dynamically allocate a number of data channels on a trunked radio system (100). The data activity is monitored during a predetermined time interval. If activity is above a predetermined maximum, an additional channel may be reserved for data use. Conversely, if data traffic is low, a data channel may be reallocated for voice message use. Moreover, should the amount of data traffic among the available data channels be unbalanced, the present method contemplates reassigning subscriber units (114 or 116) to the available data channels to balance the data traffic load, thereby providing superior access time and system performance.

Abstract: Selected regional trunking systems are equipped with telephone interconnect capability and provided with local computers (106), which communicate with a national hub computer (110). At each selected trunking system, several IDs are reserved as "roaming IDs" to be temporarily assigned to roaming subscribers (112). When a subscriber determines that it has roamed into a new trunked system, it requests a roaming ID. A roaming ID is assigned and transmitted to the subscriber, which thereafter operates within the new trunked system using its roaming ID. The roaming assignment is also transmitted to the national hub computer (110) so that interconnect calls may be approximately properly forwarded. The roaming subscriber (112) continues to operate under the assigned roaming ID until it roams out of the range of the current system and into yet another trunked system. In this way, the subscribers may roam from system to system.

Abstract: An improved communication system is disclosed wherein at least one reprogramming station is added to a communication system. The reprogramming station is constructed and arranged to communicate with the subscriber units thereby either reprogramming or regrouping them. The subscribing units receive the reprogramming command and acknowledge individually, altering a memory means until either reprogrammed back to the original state, or to another state. In another mode, the reprogramming station transmits a regrouping command wherein two or more groups are combined to form a super group.

Abstract: An optimized method of bus contention comprising monitoring the bus for an idle or busy bus condition and either attempting an asynchronous bus access if the bus is idle or synchronously attempting a prioritized retry after a busy bus condition is sensed, after a bus access collision is sensed, and upon initial power-up, synchronized to the current message completion. The prioritization comprises a constant time delay plus a bit-time delay proportional to said accessing device's address identification.

Abstract: A fault tolerance signal receiver (10) for use with differential voltage level transmission systems from which two voltage levels may be substantially simultaneously sensed to allow the two voltage levels to be decoded into digital signals. The receiver (10) includes an input unit (11) for receiving the two voltage levels and for producing outputs related to these two voltage levels, a first logic unit (12) for receiving the output from the input unit and for producing an output, with the output being selectively variable when the two voltage levels are valid and non-variable when the two voltage levels are invalid due to the presence of a fault condition in the transmission system, and a second logic unit (13) for receiving the output of the first logic unit (12) and the input unit (11) for correctly outputting a decoded digital signal (17) provided that the transmission system has no more than one fault condition present thereon. A fault condition signal (27) may also be provided.

Abstract: An MSK or OK-QPSK data signal demodulator includes a filter and limiter for filtering and amplitude limiting the data signal, a timer for generating a timing signal indicating elapsed time and a microcomputer coupled to the limited data signal from the limiter and the timing signal from the timer. The microcomputer is interrupted by each transition of the limited data signal and stores the timing signal from the timer. An interrupt routine of the microcomputer extracts the clock offset, which is an estimate of the relative location of the bit boundaries, and the phase intercept, which is an estimate of the phase of the data signal at the bit boundaries, from the timing signals.

Abstract: An apparatus and a method are provided for determining when a moving body assumes a motionless state. A rate of turn sensor is attached to the moving body. A signal indicating that the body is substantially motionless is generated when the rate of turn signal generated by the sensor is substantially constant.