Abstract: A phase-locked loop incorporates a quadrature modulator for generating constant envelope phase or frequency modulation. Locating the quadrature modulator within the feedback loop or feeding the output signal of the quadrature modulator into the feedback loop permits accurate constant envelope phase modulation of the loop reference oscillator and completely suppresses undesired AM and PM components of the modulated signal.

Abstract: An implementation of coherent diversity combining in a RAKE receiver that uses energy in signal echoes by integrating information from main-path and bit-period-delayed signal propagation paths to remove echo distortion, or time dispersion, is described. If delayed by one chip in a CDMA system, such echoes appear as uncorrelated interference. The RAKE receiver correlates a despreading code with the current (main-path) signal samples and with the signal samples delayed by 1, 2, 4, . . . bit periods, and combines the correlation results to determine the information content of the signal. After appropriate conditioning, the received signal is digitized and the signal samples are stored. Groups of samples are Fast Walsh Transformed, and the real and imaginary transforms are scaled according to a table of coefficients; the scaled results are stored. Weighted, scaled transforms of groups shifted by 1, 2, 4, . . .

Abstract: A LAN multi-node generic digital signal communications link within a radio frequency (RF) base station system communicates control signals within and between base stations. The generic digital signal link eliminates the use of multiple lines for respective functions by using the same generic communications interface for various different functions. By using such a generic digital signal link for inter and intra base station communications, RF and auxiliary control become standardized--reducing complexity in the product, in the documentation and in field repair techniques.

Abstract: A high frequency power amplifier amplifies periodic signals in the form of HF bursts. The power output of the amplifier is adjusted by a control loop which produces a control signal in response to a comparison made between a set-point value (BV) and the actual power output (Put) of the amplifier and applies the signal to the power amplifier. The control loop includes a differential amplifier. A correction circuit measures the output voltage of the differential amplifier over a time period (t.sub.1 to t.sub.2) prior to each HF burst and stores in a memory (C) a magnitude proportional to this output voltage. During the following HF burst, this magnitude is used to introduce into the control loop a correction magnitude (Ukorr) for correction of offset voltages (Uoff) occurring in the control loop.

Abstract: A digital FM base station radio having a dedicated digital signal processing (DSP) board operates on audio signals from RF links and land lines. The DSP board detects, filters and generates tones and communicates information regarding these tones to a controller microprocessor on the central control board for the radio.

Abstract: A multisite network switch for a series of RF digital trunked radio transceivers and dispatcher consoles. Each transceiver covers a certain site area. The switch establishes audio communications between different sites and various dispatcher consoles. The multisite switch has a distributed architecture in which each node of the switch is supported by a microprocessor controlled card. The nodes are connected by audio buses and a dedicated message bus. The messages on the message bus allow the nodes to communicate control information regarding the status of slots on the audio bus, the members in groups, the location of radio units, call types and a host of other information needed to operate the switch.

Abstract: A simple and effective "RF snubber" circuit resolves the problems associated with transient spectral noise caused by radio transmitter activation in nearby channels. By connecting an RF snubber circuit in parallel with the RF amplifier output, the rise time or turn-on characteristic of the RF signal generated by the transmitter is controlled. As a result, adjacent channel interference is substantially eliminated.

Abstract: In a hinge mechanism, a first hinge portion and a second hinge portion are urged toward predetermined angular relationships relative to one another. A force, directed outwardly from the first hinge portion, is applied by an axle pivotally connecting the first and second hinge portions and having a V-shaped tip against a V-shaped groove in the second hinge portion, urging the V-shaped tip and groove to engage. In addition to being urged toward predetermined angular relationships, the first and second hinge portions are kept in predetermined angular relationships until a torsional force is applied to one of the hinge portions to overcome forces keeping the V-shaped tip and groove in engagement.

Abstract: A multisite network switch for a series of RF digital trunked radio transceivers and dispatcher consoles. The switch establishes audio communications between different sites and various dispatcher consoles. The multisite switch has a distributed architecture in which each node of the switch is supported by a microprocessor controlled card. These nodes perform all of the logical functions of the switch. When the switch is booted-up or reset, each node executes a dynamic address generation algorithm to select a unique address and resolve any address conflicts with other nodes.

Abstract: A digitally trunked radio repeater system provides substantial improvements in timeliness of channel acquisition and channel drop, and in reliability of critical control signalling. The system uses a much higher digital signalling rate than is typically found in prior art systems, and uses a control channel to convey digital channel request and assignment messages between the central site and mobile transceivers. The mobile radio transceivers transmit channel requests on the control channel (if no response is received, the mobile retries during a retry time window which increases in duration in dependence on the number of retries). The mobile transceiver switches to a working channel in response to an assignment message received on the control channel. Subaudible digital signals transmitted on the control channel and on active working channels allow late entry, shifting to higher priority calls, and other advanced functions.

Abstract: A site architecture for a trunked radio frequency communications system provides better fault tolerance capabilities than are available from architectures including redundant hardware. During normal system operations, a primary site controller performs most or all system control functions while signal processing functions are performed in a distributed manner by trunking cards associated with individual repeater channel receivers and transmitters. In the event the site controller fails, the trunking cards also begin performing trunking and other control functions. The trunking cards cease attempting to communicate with the failed site controller, and begin communicating directly with one another via a high speed backup serial link.

Abstract: A clip for surface-mounting a coupled-dual resonator crystal to a circuit board includes an elongated housing shaped complementary to the housing of the crystal and having an opening along a side for receiving the crystal. A tab spaces first and second shielding portions which overlie the end of the crystal housing. A first shield portion engages the middle ground terminal of the crystal shielding the input and output terminals, while the second shield extends from the first shield to overlie the output terminal, likewise shielding it from the input terminal. Distal portions of the input, output and common terminals, together with pads at the opposite end of the clip, mount the clip mechanically to the surface of a circuit board.

Abstract: A system and method for communicating control signals between a digital mobile transceiver, a digital control head, and a mobile data terminal over a common serial peripheral bus uses a message protocol and architecture which is efficient and yet provides great versatility and functionality without adding undue complexity. As mobile data terminals are becoming increasing important in digital trunked repeater systems, the efficiency provided by the signalling protocol disclosed herein (which is optimized for mobile data terminal messages) is a very important advantage.

Abstract: An apparatus and method of modular electronic printed circuit board design for a radio communication transceiver in which the electronic circuitry forming a transmit/receive circuit board of the device is modularized in such a manner as to facilitate independent stand-alone functional testing of modules both on and off the board.

Abstract: A multisite network switch for a series of RF digital trunked radio transceivers and dispatcher consoles. The switch establishes audio communications between different sites and various dispatcher consoles. The multisite switch has a distributed architecture in which each node of the switch is supported by a microprocessor controlled card. This card has a communications controller that routes messages between the internal switch bus, an outside port and an interface processor that controls the audio slots in the switch. The communications controller receives control messages from the switch bus, but discards redundant slot status messages by checking a slot status bit map stored in a memory unit on the card.

Abstract: The frequency stability of the signals transmitted by a plurality of mobile stations to an associated base station within a radio network is supervised by first generating a reference signal at the base station. The signals received from the mobile stations are compared to the reference signal and a difference signal is generated. The difference signal is compared to first and second error values and if the difference exceeds the first error value, the mobile is summoned for a service adjustment. If the difference exceeds the second error value, the mobile is disabled from further transmissions.

Abstract: A radio frequency (RF) base station transmitter receiver (transceiver) system includes an audio compression arrangement that compresses a sum of multiple audio signals so that all signals within the sum are equalized to a substantially uniform audio output level despite differences in their input levels. Compression thresholds can be adjusted from a remote location. The RF base station provides audio signal compression using digital signal processing (DSP) techniques such that advanced features (e.g., noise blanking and hard limiting) and flexibility are built into the system. Line audio inputs from several sources are filtered, converted to digital signals, and processed by a digital signal processor (DSP). This DSP provides an audio compression function that selects and applies appropriate gains to the digitized audio signal. The compressed signal is converted to analog form, filtered and routed to a variety of destination such as a RF transmitter modulator or a land line.

Abstract: A system for the resynchronization of a rolling key used as an input among a plurality of inputs to an authentication algorithm executed in a mobile station and in a radio network providing service to the mobile station. In one aspect of the system, the network rolling key input is set to a selected value and the mobile station is commanded to set the mobile station rolling key input to the same selected value. The mobile station will then set the mobile station rolling key input to the selected value in response to the command from the network.