Abstract: In order to synchronize wideband signals in time while reducing the necessary amount of processing, a number of narrowband signals (203, 205, 207, and 209) are modulated (503) on their own frequency sub-carriers, such that the summation of these modulated signals remains within the bandwidth of the wideband signal (201). This composite signal is transmitted (507) to a receiver, which uses a matched filter bank (405) to recover timing data from each transmitted frequency sub-carrier.

Abstract: In simulcast systems, overlapping coverage areas (111, 113, 115, and 117) of base sites (101, 103, 105, and 107) result in distortion of the received signal to any communication unit (121 and 125) within the overlapping area. This distortion occurs because the signals are not completely time and frequency aligned when they reach the communication unit (121 and 125) due to differences in distance and geographical obstructions between the transmitters and the receiving unit. A simulcast system is provided that uses unique base site IDs to allow mobile units to locate themselves within the system. This ID system is also used to assign one site to a mobile unit (121 and 125) residing in an overlapping area, and thereafter to identify the minimum number of base sites needed for a transmission to all the relevant communication units (119, 121, 123, 125, and 127). Only those base sites (101, 105, and 107) needed to complete a transmission are enabled, eliminating distortion to units (121) in overlapping areas.

Abstract: A diversity repeater that incorporates diversity diagnostic circuitry. The diversity diagnostic circuitry monitors the outputs of at least two receivers and determines the signal strength of the transmissions received by each receiver. If the signal strength for a particular receiver is below a predetermined threshold, the diversity diagnostic circuitry determines whether that receiver is receiving a rayleigh faded transmission or is an inoperative mode.

Abstract: To compensate the audio distortion resulting from amplitude and phase imbalance in the quadrature oscillator (103) and mixers (105, 115) in zero-IF downconverters (203), a balancing action is required. An apparatus for distortion compensation compensates for the amplitude and phase imbalance to reduce audio distortion. This is accomplished by determining (309) two gain values, which are combined (217, 227, 229) with the in-phase and quadrature components of the zero-IF downconverter (203) to compensate for the imbalance.

Abstract: A method and means of automatically accessing several types of radio systems is described. The present invention allows a subscriber unit, which is normally operative in a operator selected radio system, to establish communication with an alternate system if a operator selected system cannot be found. The alternate system may be a conventional single channel mobile relay system or trunked radio system in which the subscriber is authorized to operate. Once communications are established with an alternate communication system, the present invention will periodically attempt to establish communication with the operator selected system while simultaneously attempting to be assigned a higher priority channel in the alternate communication systems according to a priority scan list. Further, the present invention will automatically ignore certain channels which are dedicated for car-to-car use.

Abstract: In a network of communication systems that comprises a plurality of communication systems, the following discloses a method that allows a communication unit that is seeking a communication system to monitor to verify the integrity of both the transmit communication path and the receive communication path. The first step is for the communication unit to acquire synchronization with the communication system. Having acquired synchronization with the communication system, the communication unit receives transmission parameters of the communication system. Based on the transmission parameters, the communication unit calculates a talk-out gain of the transmit communication path and a talk-in gain of the receive communication path and then calculates a transmit communication path loss and a receive communication path loss.

Abstract: A method of effecting handoff of a communicating communication unit from a first communication resource to a second communication resource. After determining that a handoff from the first communication resource to the second communication resource should likely be made, the method makes determinations regarding relative levels of communication degradation that will likely occur when using different handoff methodologies to effect the handoff. In general, the method selects a particular handoff methodology that will provide a best level of handoff reliability while simultaneously posing at least no more than an acceptable level of communication degradation.

Abstract: Lag information for use in a speech coder is developed by estimating lag values for the various subframes (201) of a speech coding frame (200) of information, and by then selecting lag values for each subframe that are both closely corresponding to the estimated lag values and that also observe the restrictions of a selected delta-coding routine. When a plurality of candidate sets of such information have been developed, they are compared against one another to identify that set which appears to provide the best set of lag values. This information is then available for framing and transmission. In one embodiment, the sets of candidate values are also selected to ensure provision for subsequent adjustment in either a positive or negative direction.

Abstract: In a communication system that includes a plurality of communication units, a limited number of communication resources, and at least one operator station, the operator station can monitor audio messages produced by plurality of communication units in the following manner. Upon receiving at least one audio message generated by at least one of the communication units, the console will buffer the received audio message and establish a group of buffered audio messages. From the group of audio messages, the console selects at least one of the buffered audio messages pursuant to a pre-established selection procedure. Once an audio message has been selected it is retrieved and processed to render the audio message audible.

Abstract: A voltage sensing circuit is used to determine when the current supply to a processing unit is under transition. During power up transitions, the voltage sensing circuit allows the processing unit to reset normally. During power down transitions, the voltage sensing circuit prevents the processing unit from resetting until a predetermined procedure has been completed, thereby assuring an orderly shutdown.

Abstract: A first heat sink member with extension slots and component detailing is cast from a thermally conductive material. Fin members are constructed from a similar, but not necessarily identical, thermally conductive material. The fin members are constructed so that they will mate with the extension slots of the first heat sink member. Positioned in alignment with the extension slots to the first heat sink member, the fin members are attached with a thermally conductive bonding agent.

Abstract: An electronic device package includes a portion that functions as a membrane to allow small molecules, such as gas molecules, to relatively freely traverse the housing boundary, while simultaneously substantially preventing large molecules, such as liquid molecules, from entering the confines of the housing. As a result, the package can be readily used in reflow processing without risking damage to the boundary integrity between the housing and the support surface that supports both the electronic device and the housing.

Abstract: An adaptive spectral postfilter in a synthesized speech platform has a denominator characteristic that corresponds to a preceding LPC filter stage, and a numerator characteristic that is developed as a function of the denominator characteristic through application of spectral smoothing techniques. This allows the numerator to track the denominator without the introduction of spectral distortion that would otherwise affect the processing in an adverse way.

Abstract: Authentication of system status OSWs in a trunked communication system is provided by first verifying (411) that a received system ID (313) matches a pre-programmed system ID. A system status OSW must then be matched twice before the information in the system status OSW is programmed into a communication unit (115), thus limiting the possibility of false decoding of system status OSWs.

Abstract: A method (215) of converting a current control channel for use as a communication (voice/data) channel, in order to maintain a predetermined level of service in a radio communications system, employs a central controller (101) to allocate a limited number of communication channels among a plurality of subscriber units (108-112). After receiving (203) a request for a communication channel from one of a plurality of subscriber units (108-112), the controller (101) determines (205) whether all of the communication channels are busy. The controller then temporarily converts (215) the current control channel to a communication channel.

Abstract: A personal communicating computer (112) (FIG. 1) remains in contact, via a wireless network, with an office server (101). Documents from various sources can be transmitted to the personal communicating computer (112) using this network. Upon receipt, such documents can be accessed and utilized in a variety of ways. In particular, such documents can be annotated in a variety of ways, and those annotations forwarded on to other destinations for appropriate review and handling.

Abstract: A method of synchronizing a plurality of remote site transmitters (200) in a digital simulcast transmission system is described that enables use of four-level modulation on two-level modulation systems. A synchronization signal is transmitted at a predetermined data rate from a prime site, which signal might include a synchronization pattern having a first and a second portion. The first portion of the synchronization pattern is used for synchronization, while the second portion indicates the completion of the first portion. The method includes detecting (205, 320) of the first portion of the synchronization pattern. Each remote site transmitter (200) further has a modulation clock having a phase polarity which is selected (215, 324) in response to the detection of the first portion of the synchronization signal.

Abstract: In a geographic region that contains a trunking communication system and a cellular communication system, wherein the coverage area of each system substantially overlaps, a method that transfers a private data transmission from the trunking communication system to the cellular communication is disclosed. When a data transmission unit is prompted to transmit data, it transfers its affiliation from the trunking communication system to the cellular communication system. Once affiliated with the cellular communication system, the data transmission unit transfers its data via the cellular communication system. The trunking communication system detects the requested data and routes the requested data to the appropriate data target. Once the data transmission unit has transmitted the requested data, it transfers its affiliation back to trunking communication system.

Abstract: A resilient housing actuated multi-level housing switch comprises a compression sensitive circuit which is actuated by compressing a resilient housing. The compression sensitive circuit comprises a compression sensing device which produces an analog signal, an A to D converter, and a microprocessor. The microprocessor is programmed with algorithms to control the power levels of communication equipment and volume levels based on signals produced by compressing the compression sensing device.