Abstract: A method for a non-registered communication unit to access a communication system consists of sending a service request. Upon receiving a service request, the communication resource allocator assigns an entry in the communication system database to the non-registered unit and assigns system default features to the entry such that the unit has default access to the communication system. Thus allowing a communication unit that has subscribed to system services and has not been recognized by the system manager to access the system utilizing default parameters until the system manages properly registers the unit.

Abstract: A secure communication system (100) that is capable of over-the-air-rekeying (OTAR) employs a key management controller (108) to provide secure communications for a requested call. The key management controller determines (403) when the requested call has been initiated and identifies (405) some of the plurality of radios as being members of the requested call. A call key is then transmitted (409) to the members of the requested call where it is used (514) for the duration of the requested call. In this manner, secure communications between the members of the requested call is provided.

Abstract: Time division multiplex (TDM) radio communication systems require a method of providing communication service to a plurality of subscribers throughout a coverage area. This coverage area typically includes a central resource allocator and a plurality of satellite receivers throughout the coverage area. The method includes the step of, upon receipt of a transmission from a subscriber, transmitting to the central resource allocator an arrival time for the transmission. The central resource allocator then selects, based at least in part on the arrival time, a favorable satellite receiver for facilitating subsequent transmissions from that subscriber.

Abstract: A heat sink assembly (100) employs multiple heat sinks (401-403) that are juxtaposed to provide pneumatically coupled air flow pathways. At least one of the heat sinks (401) preferably includes an air circulator to force the air flow towards a periphery of the heat sink. A plurality of heat radiating surfaces provide pneumatic pathways (201) for the air flow, and at least two of the pneumatic pathways (201) are arranged substantially non-parallel. In this manner, the air is forced (i.e., when an air circulator is provided) radially from a center point of the heat sink (200) toward a periphery. Similarly, the air is directed (i.e., when an air circulator is not provided) toward a central locale from the periphery of the heat sink (300).

Abstract: A linear transmitter (100), which utilizes closed loop feedback to maintain its linearity, employs a method for reducing off-channel interference produced by the linear transmitter (100). A dynamically alterable parameter source (DAPS, 126) is provided to the linear transmitter (100). The DAPS (126) is then used to adjust at least one loop parameter of the closed loop feedback such that off-channel interference is reduced.

Abstract: A data communications system comprising first (B), second (C) and third (A) remote units arranged for communication over a common communications channel. A first message to be sent to the second unit (C) is generated at the first unit (B). The first unit (B) waits for the channel to become available for independent transmission of the message. If (t.sub.0), before the channel becomes available for independent transmission, a new message is received from the third unit (A) requiring an acknowledgement, the new message is received from the third unit (A), an acknowledgement of receipt of the message is transmitted (t.sub.1) and in a substantially continuous transmission (t.sub.2), the first message to the second unit is transmitted in a "piggy-back" manner. In a preferred arrangement, multiple messages can be piggy-backed to different units. Priorities can be assigned to these messages for acknowledgements.

Abstract: In a radio transmitter (100) that includes a power amplifier (104) and an antenna (106), a method for enhancing an operating characteristic of the radio transmitter (100) can be accomplished in the following manner. The power amplifier (104) provides a signal (113) to a variable matching network (111), wherein the signal (113) comprises energy to be radiated by the antenna (106). The variable matching network (111) couples the signal (113) to a sampler (112) that is operably coupled to an output of the variable matching network (111 ) and the antenna (106). The sampler (112) samples a forward component (114) and a reflected component (115) of the signal (113). The radio transmitter (100) processes the sampled forward and reflected components (116, 118) to produce a feedback control signal (120). The feedback control signal (120) is used to adjust the variable matching network (111 ), such that an operating characteristic of the radio transmitter (100) is enhanced.

Abstract: A TDMA radio communication system provides communication service to a plurality of mobile communication units through use of a TDMA frame. The TDMA frame includes a plurality of timeslots that are distributed across a TDMA frame duration and are used to facilitate communications involving a first mobile and a second mobile. Audio delays are reduced using a method that includes the steps of measuring a hold time for each of the mobiles, and determining a present aggregate hold time based at least in part on the measured hold times. When the present aggregate hold time exceeds the TDMA frame duration, the method provides for the re-assignment of at least one of the mobiles to an alternate timeslot within the TDMA frame.

Abstract: A multi-site communication system (100) includes a plurality of communication units ( 112-117), a central controller (101) for coupling a plurality of communication sites (106-108), and a site controller (103) corresponding to one of the communication sites (106). Communication access between two or more communication units (112-117) can be enhanced by a method (200, 300) including the steps of receiving (201) a request for a first communication, and directing (211) the appropriate site controller to re-submit the request. By so doing, the site controller (103) can request (314) the central controller (101) to establish a realizable communication between two communication units in the system (113, 114).

Abstract: A receiver (100) that includes an antenna (101) employs a method and apparatus for producing diversity gain of a signal (106) received by the antenna (101), wherein the signal (106) is subject to a time-variant fading condition. Upon receiving the signal (106), the receiver (100) determines a signal quality metric of the signal (106) and compares the signal quality metric to a quality threshold. When the signal quality metric is below the quality threshold, the receiver (100) orients a predetermined antenna pattern (304) of the antenna (101) to improve the signal quality metric, thereby producing the diversity gain.

Abstract: A communication unit that is registered in a trunked communication system can continue to receive a communication from a first communication unit after initiating a push-to-talk request while the first communication unit is transmitting voice data in the following manner. Having allocated a communication resource to a group of communication units and while processing a request to communicate for the first communication unit, a communication resource allocator receives a request to communicate from a second communication unit to produce a new request to communicate. The communication resource allocator stores the new request to communicate and transmits a response to the second communication unit such that the second communication unit can continue to receive the remainder of the communication from the first communication unit.

Abstract: A method of reliably transmitting signalling tones employs a radio communication unit suitable for encoding (303) data packets. The radio has a processor (101) for processing a first signal, which processing is incompatible for use with signalling tones. The radio further includes an input device (110) for providing signals when asserted. In a preferred embodiment, when the processor (101) is enabled to process the first signal, and a user does not assert the input device (110), the radio transmits the processed first signal. On the other hand, when the processor (101) is enabled, and the user asserts the input device (110), the radio transmits (304) repeated data packets, for the duration of the assertion, which identify a particular signalling tone.

Abstract: A data transmission scheme for use in a low channel bandwidth-to-modulation symbol rate ratio (BW:R.sub.S) application employing a linear modulator for producing in-phase and quadrature (I and Q) components of a data stream inputted at a predetermined symbol rate. This transmission method allows for the recovery of signals having unfavorable delay spread characteristics. That is, a specialized function is used to process the I and Q components, whose time domain transfer characteristic remains within a predetermined range of a data constellation point for a duration that exceeds 25 percent of a symbol period corresponding to the predetermined symbol rate. The processed response is then band-limited to produce a modulation signal that is usable in the low BW:R.sub.S application.

Abstract: Memory (120) in a device (100) that includes a power source (105) is erased when an alarm triggering event is detected. An alarm signal is provided that is used to determine whether the memory (120) has been erased since a transition from normal to low power mode. It is only when the memory (120) has not been erased since such a transition, that the memory (120) is erased, thereby providing an energy efficient erasure process.

Abstract: Determining transmit time of a received signal in a simulcast multi-site communication system begins when a communication unit transmits a message to one or more network receivers. The receivers transport the received signal with a time stamp to a master transceiver in the network via a digital communication network. The master transceiver then determines a launch time for transmission of a selected received signal, wherein the launch time is based on a previously executed procedure to determine the inbound and outbound delays in the simulcast multi-site communication system. Finally, the master transceiver transports the selected received signal with the launch time to other transceivers assigned to the call, wherein the transceivers transmit the selected received signal at the launch time.

Abstract: A radio communication system controller (100) includes a first (103) and second (104) processor for processing input communication messages (101) used in a radio communication system. The controller (100) further includes shared memory (105), which memory is accessible to each of the first (103) and second (104) processors, for storing the input communication messages (101). The controller (100) is further equipped with fault detection capability (107) for determining (402) when a processing fault has occurred.

Abstract: A radio system user (126) is alerted (129) as to the occurrence of a financial transaction by a customer (118). Data (122) is obtained from the customer (118) and used to identify a radio system user (126), who is authorized to conduct the financial transaction. A message, indicative of the financial transaction, is automatically provided to a radio system and broadcast (129) to the radio system user (126), thereby alerting the user (126) to the financial transaction.

Abstract: A radio transmitter includes a power amplifier (12); a linearizer (10) for maintaining linearity in the power amplifier; and a feedback path (13) for feeding a signal from an output of the power amplifier to the linearizer. The amplifier, linearizer and feedback path cooperate to form a feedback loop having adjustable loop linearization parameters (for example phase and gain). Further, a look-up table (19) is used to store predetermined loop linearization parameters and cooperates with a microprocessor having an operating condition input.

Abstract: In a radio communication system, a method of transmitting encoded data includes providing a plurality of discrete data elements to be presently transmitted. These data elements are then encoded using a first encoding technique. An indication is then provided when at least some of the encoded discrete data elements have been compromised. At the receiver, it is determined whether at least some of the received, encoded, discrete data elements have been compromised. A decision metric is then provided based on this determination, and the data elements are decoded using the decision metric.

Abstract: A filter (200) having an input terminal (208), an output terminal (209), and a common terminal (210) includes two impedance inverters (201,202) and a first resonator (203) that is operable at a resonant frequency. Each impedance inverter (201, 202) is coupled to the common terminal (210) at a common node (223) and includes a corresponding input node (221,225) and output node (222, 226). The input node (221) of the first impedance inverter (201) is coupled to the input terminal (208). The input node (225) of the second impedance inverter (202) is coupled to the output node (222) of the first impedance inverter (201), while the output node (226) of the second impedance inverter (202) is coupled (e.g., via a second resonator (205)) to the output terminal (209). The first resonator (203) is coupled between the input terminal (208) and the output terminal (209).