Abstract: A radio communication system (200) having a communication site (203) provides communication services to a coverage area (201) surrounding the communication site (203). A plurality of service resources are allocated (318) among a plurality of communication units (205) located within the coverage area (201). A method of responding to a service request transmitted from a requesting communication unit includes the steps of determining (310) a nominal service duration, and estimating (312) an available site time value. A completion probability value can then be calculated (403) using these parameters. The completetion probability value is then used to determine (405-413) whether or not to allocate, to the requesting communication unit, a service resource corresponding to the requested service.

Abstract: In a secure trunked communication system that includes a central controller, communication between a distribution panel and a limited number of console interface units may be achieved in the following manner. At power up or upon a reset condition, the distribution panel transmits a status check message to each console interface unit in the system. Console interface units that are active respond by transmitting an acknowledgement. Upon receiving the acknowledgement, the distribution panel transmits the addresses of the active console interface units to the central controller. When the distribution panel receives secure information from the central controller, it interprets the information to identify a target console interface unit and transmits the received secure information to the target console interface unit.

Abstract: A transmission line resonator assembly (100) employs a method and apparatus for adjusting its resonant frequency. The transmission line resonator assembly (100) comprises a resonator portion (101) and an electrically conductive member (102). The resonator portion (101) is operable at the resonant frequency and includes a transmission line (103) that is disposed on a dielectric material (104). A first portion (106) of the transmission line (103) is electrically coupled to a signal common (109) by a first coupling impedance. The electrically conductive member (102) includes a first deflectable surface (113) lying substantially along a first plane (201) and is coupled to the resonator portion (101) and the signal common (109), such that the first deflectable surface (113) is positioned substantially adjacent to the transmission line (103).

Abstract: Audio communication may be established between a plurality of communication units in a communication system that includes a dispatch switching center in the following manner. A first communication unit generates information to be distributed to a second communication unit. The dispatch switching center receives a digital packet including the information to be distributed, and ascertains an identifier associated with the second communication unit. The dispatch switching center replicates the information to be distributed, and uses the identifier to distribute the replicated information to the second communication unit.

Abstract: An improved integrated circuit (IC) comprises test logic circuitry operably coupled to a serial port, multiplexing circuitry coupled to the output of the IC and a data bus, and gating circuitry coupled to logic sections of the IC and the data bus. The IC may be tested by providing test parameters to the IC which includes identification of a particular logic circuit to be tested and test vectors for the particular logic circuit. Next, access is provided to the data bus for the particular logic circuit based on the test parameters. Finally, external test equipment is provided access to part of the data bus based on the test parameters such that the external testing equipment monitors data placed on the data bus by the particular logic section.

Abstract: A circuit for protecting direct current (DC) powered devices from excessive supply voltage and reverse polarity supply voltage comprises supply voltage coupling circuitry that operably couples a DC powered device to a supply voltage. The circuit also includes a first field effect transistor (FET) having an intrinsic diode operably coupled to the supply voltage coupling circuitry. Further, the circuit includes first current blocking circuitry operably coupled to the first FET for blocking current flow through the intrinsic diode. Still further, the circuit comprises gate supply circuitry operably coupled to the first FET and the supply voltage coupling circuitry to supply gate voltage to the first FET when the supply voltage is less than a predetermined value.

Abstract: A motion sensing apparatus comprises two substrates, contact means, and at least one electrically conductive element. A first substrate contains an electrically conductive layer disposed on one of its major surfaces. A second substrate contains a hole, including an interior surface that extends from one major surface to another, such that a cavity is formed by the planes of the major surfaces and the interior surface. The second substrate is positioned substantially parallel to the first substrate, such that the electrically conductive layer is positioned within an area defined by the hole. The contact means and the electrically conductive element are placed within the cavity, such that a motion sensing signal is produced when the electrically conductive element comes in contact with both the contact means and the electrically conductive layer.

Abstract: A method of tracking subscribers (201, 203) in a networked radio communications system (100, 200). The subscribers (201,203) are able to roam among a plurality of coverage areas (104-106) which are serviced by a plurality of transmitters (107-109). The transmitters (107-109) are coupled to a central processor (CP, 110), which accesses a memory device (112) for storing subscriber records and site records. Subscriber records include location information for each of the subscribers, while the site records include a logical representation of geographical relationships between the coverage areas. The method relies on the subscriber to send an inbound message (330) which includes its current location. Further, the CP (110) records a message time for the inbound message, producing a timestamped location, then updates (405) a corresponding portion of the subscriber record with the timestamped location.

Abstract: In a power supply that includes switch-mode feedback, output transient responses can be minimized by first detecting a predetermined load change. Once the load change has been detected, the switch-mode feedback is adjusted for a predetermined period of time to a maximum level for load increases or to a minimum level for load decreases. When the predetermined period of time elapses, the switch-mode feedback is adjusted to an output voltage dependent mode of operation.

Abstract: In a communication system, a password that enables an embedded software program within a base station can be generated using public key cryptography in the following manner. A system controller (103) obtains a unique identification code and an embedded software code for the base station (101). Once obtained, the system controller (103) encrypts the unique identification code and the embedded software code using a private key to produce a password. The password is transferred to the base station (101) where, upon receipt, is decrypted using a public key to produce the unique identification code and the embedded software code. The base station (101) compares the unique identification code and an embedded unique identification code (107) and, when they substantially match, the base station (101) stores the password.

Abstract: In the following manner, a receiver that receives quadrature modulated signals may determine desired components of the quadrature modulated signals by minimizing effects of transmitted distortion produced by gain, phase, or gain-phase imbalance. A quadrature modulated signal that includes a desired component, a fading component, and a transmitter distortion component is received by the receiver, wherein the transmitter distortion component includes a conjugate component and an imbalance component. The receiver estimates the fading component, the conjugate component, and the imbalance component and determines the desired component based on these estimates and the quadrature modulated signal.

Abstract: A radio communication system (600) having at least two radio interface devices (602) requires an access protocol for accessing a common information bus (605). The bus (605) is necessary for sending information to a communication system controller (601). A first of the interface devices periodically polls the common information bus (605) to determine whether or not it is available for sending information to the communication system controller (601). When available, the device acquires access to the bus (605), and sends information to the controller (601), via the information bus (605). The device then releases the bus (605) at a subsequent polling period for that device, thereafter allowing a second interface device to gain access to the bus (605). The foregoing sequence ensures that each of the interface devices (602) will, within a predetermined time, poll the bus (605) and acquire it, as necessary, for sending information to the system controller (601).

Abstract: A test device (101) for use in a trunked radio system (102) employs a received signal strength indicator (RSSI) detector (120) to analyze transmission parameters. The test device (101 ) includes a transceiver (118) for transmitting and receiving radio signals, and a channel controller (116). The test device further includes memory (117) for storing (403) data, and test control means (116) for causing the transceiver to receive (303, 406) outbound signals on active communication channels. The test device (101) then processes (303-305, 402-404) the power levels for the outbound signals, and either re-transmits (305, 307) the results, or stores (407) them in memory.

Abstract: In a radio communications system, a selectively enabled time- and/or frequency-diverse signaling scheme is employed to improve signal quality. In particular, a method of exchanging a message between communication devices using a communications resource might include the step of transmitting a first portion of the message on a first frequency within the communications resource. After determining the quality of the communications resource to be unfavorable, a second portion of the message might be transmitted on the first frequency, and also re-transmitted on a second frequency and/or at a separate time.

Abstract: A method is disclosed which automatically establishes a communication path between at least two devices (106, 110, 118, 120, 128). Each device has a unique identification (ID), and is coupled to a switching center (132-137) of a Public Switched Telephone Network (PSTN, 130). The PSTN (130) has a facility access center (FAC, 140) for coupling the switching centers (132-137) to a storage facility controller (SFC, 146), which provides access to a central storage facility (148). The method includes the steps of determining (306) an ID of a first device and then selecting (318) a portion of the central storage facility (148) associated with that ID. Then, after ascertaining a second ID of a second device, an element associated with the second ID is retrieved (322) from that portion of the central storage facility (148). Lastly, a communication path is created (327, 328) between the first device (106, 110, 118) and the second device (108, 112, 128).

Abstract: A data transmitter (100) operating at a transmit frequency provides a modulated data signal (114) by adjusting a reference frequency signal (108). The method of modulating an N-level data signal (102) inputted to the transmitter (100) provides for inputting, to a signal processor (201), a frequency deviation value. Using the frequency deviation value, the signal processor (201) then determines a maximum rate of enabling the frequency adjustment. Further, a deviation ratio corresponding to one of the N-levels is determined, and an increment value is then calculated (302) using this deviation ratio. Lastly, the frequency adjustment is enabled (312, 320) using the calculated increment value.

Abstract: A shielding apparatus for use with a non-conductive package has an insulated lid (102) which is retained in contact with a substrate (104) for holding an electrical circuit. The shielding apparatus includes a first conductive flash (201) deposited on the interior surface of the insulated lid (102), to produce a substantially contiguous conduction layer, and a second conductive flash (203) deposited over a film (110) disposed on the edge of the insulated lid (102), to produce a partially contiguous conduction layer. The shielding apparatus also includes a layer (108) for affixing the insulated lid (102) to the substrate (104), to produce an enclosure for isolating the electrical circuit from extraneous radio frequency (RF) energy.

Abstract: A method of collapsing a communication path among at least two communication units (104-107) reduces the number of sites normally required to provide a communication. Each of a plurality of site controllers (103) in a radio communications system has a corresponding coverage area (100, 101), and at least some of the coverage areas (710-712) overlap one another. The method includes the step of determining (402) whether the communication units are currently being serviced by different sites, and then determining (405) whether they can be serviced by a common site. When the communication units are serviceable by a common site, the call might be established (406) through the common site, resulting in a reduced number of sites required to complete a call.