Abstract: The present invention relates to a divider for dividing a dividend by a divisor. The divider includes a subtractor for subtracting the divisor from the dividend to produce a result, storage space with a preliminary answer, and a processor for revising the dividend and preliminary answer based on the result. Each interation the divider is adapted to reiterate the subtraction and revision multiple times, based on a revised dividend and revised preliminary answer.

Abstract: Embodiments of the invention assist conversion of an old data table to a new data table in a communication terminal. An edit script is created by creating an old and new data trees from the old and new tables respectively. A first partial script which converts the old tree to an intermediate tree having the same length as the new tree is then determined. A second partial script which converts the intermediate tree to the new tree is also determined. The first and second partial scripts are then combined to provide a script which can be sent the terminal. The first partial script is preferably a minimum cost series of edits causing only insertions and deletions in the old data tree. The second partial script is preferably a minimum cost series of edits causing only substitutions in the intermediate tree.

Abstract: Encryption keys in a communication system are updated according to rekey groups having a common set of encryption keys or CKRs. Each group includes a number of radios with active and inactive keysets. A database records the relationships between rekey groups and keys, and the status of their keysets. An operator first determines one or more keys to be updated. New keys are then transmitted to each radio in one or more rekey groups using respective rekey messages. The new keys are stored in the inactive keysets of the radios. The inactive keysets are then activated using respective changeover messages. Deployment of new keys is carried out by software in the form of automated update tasks.

Abstract: A graphical management interface for a radio station that simplifies programming interactions for a user. The interface has a display region for presenting programmed functions of the station. The region has first and second controls for user selection of input conditions to form programmed functions, and for user selection of output actions to be carried out by the station in response to the selected input conditions. At least one further control for user editing of the functions is also provided. The first and second controls list substantially every available input condition and every available output action of the station for selection by the user. Backplane management of the station can also be done in software.

Abstract: A repeater which enables portable radio terminals to operate outside the normal coverage area of a trunked radio network. The repeater combines two wireless transceivers which may simply be radio terminals coupled together in a vehicle, for example. One transceiver communicates control messages to and from the trunked network using a full or half duplex channel. The other transceiver communicates with the portable terminals using a half duplex or simplex channel. The link from the repeater to the network includes a generally continuous control channel while the link to the portable terminals is generally non continuous with intervals for messages from the terminals back to the repeater.

Abstract: A battery charger for a portable radio having a cradle which holds and charges a radio with a battery attached, or optionally holds and charges the battery alone. The cradle is typically mounted in a vehicle. A lock element is provided in the cradle to engage the battery and is operated by a lock actuator and a release actuator. The lock actuator is displaced when the radio or battery is pushed into the cradle by a user. The release actuator may be displaced by the user to disengage the lock from the battery.

Abstract: Radio units of a radio communication system are grouped by selecting one or more radio units in the system to form a group, selecting an identification code for the group, determining an alphanumeric label for the group, sending a new group message to each of the selected radios containing the identification code and the label, and storing the code and the label at each of the selected radios. These operations may be performed by a dispatcher terminal for a radio communication system. Each radio unit of the radio communication system is configured to receive a regrouping message containing a group identification code and an alphanumeric label from the dispatcher terminal, and create a data record that represents the new group in its memory.

Abstract: A latching assembly for securing a battery package (12) to a portable communication device. The latching assembly includes a pair of opposed moveable latches (10), each latch (10) being located toward a side of the battery package, and a biasing member or members (13) arranged to bias the latches (10) away from each other to engage with respective catches on the portable communication device to thereby secure the battery package (12) to the portable communication device. User contacts (15) are also provided and these are operable to cause the latches (10) to move toward each other to disengage from their respective catches to enable the battery package (12) to be removed from the portable communication device.

Abstract: A method of arbitrating group calls in a digital mobile radio system without need of a central component. In general terms the base station that are serving mobile units in a call each announce the nature of the signals that they are receiving. The stations then each compare the signals and decide which signal will be broadcast to the mobile units. The signals are preferably transmitted between base stations via a packet network using IP multicast.

Abstract: A repeater system for hand portable radios that may be outside normal coverage in a mobile radio system. Short messages or emergency messages from the portable radio are transmitted to an on-board or other mobile station, and forwarded from there to a central station or other required station in the system. The on-board station generally has a higher powered transmitter than the portable station and is within network coverage when the messages are received. The on-board station might be carried by a vehicle for example, and the portable station might be carried by a public safety official who has left the vehicle to investigate a nearby event.

Abstract: A latching assembly for securing a battery package (12) to a portable communication device. The latching assembly includes a pair of opposed moveable latches (10), each latch (10) being located toward a side of the battery package, and a biasing member or members (13) arranged to bias the latches (10) away from each other to engage with respective catches on the portable communication device to thereby secure the battery package (12) to the portable communication device. User contacts (15) are also provided and these are operable to cause the latches (10) to move toward each other to disengage from their respective catches to enable the battery package (12) to be removed from the portable communication device.

Abstract: A control loop (10) for producing an output signal with a stable nominal frequency is provided. The control loop includes inputs for reference (11) and oscillator (25) output signals, a beat frequency generator (12) for producing a signal with a frequency that is the difference between the oscillator and reference signal frequencies, an ADC (14) to convert the beat frequency to a digital beat frequency signal, an estimator (17) for estimating the frequency or phase of the beat signal, an adder (18) for combining an offset and modulation signal and the estimated frequency or phase of the beat signal into an added signal, and a DAC (23) for generating an analogue control signal for controlling the oscillator output frequency.

Abstract: The present invention relates to a divider for dividing a dividend by a divisor. The divider includes a subtractor for subtracting the divisor from the dividend to produce a result, storage space with a preliminary answer, and a processor for revising the dividend and preliminary answer based on the result. Each interation the divider is adapted to reiterate the subtraction and revision multiple times, based on a revised dividend and revised preliminary answer.

Abstract: The invention involves a proactive shift of a control channel among a range of available channels in a mobile radio network, particularly traffic channels. The control channel is intermittently shifted in a periodic or non-periodic manner, thereby making the frequency available for use in other networks. A round-robin process may be used to re-allocate the control channel among traffic channels. This is useful in a network operating within a common channel environment where activity on a fixed the control channel can be unfair or interfere with other networks.

Abstract: A simulcast system for transmitting and receiving signals through a plurality of remote sites within a certain area is generally described. The system automatically equalizes signal characteristics in transmission overlap regions between adjacent sites so that mobile units within the area receive signals of acceptable quality. A particular site is chosen to provide reference characteristics and a series of consecutively adjacent sites are then equalized in pairs. A control site sequentially transmits and receives a training signal through each site to determine an adjustment which will equalize the signal characteristics of successive sites in the series.

Abstract: A zero intermediate frequency radio receiver that comprises mixing stages, an A to D converter, a digital demodulator, a carrier tracking system and a carrier nulling system is disclosed. The mixing stages receive FM or PM signals and produce analogue in-phase and quadrature baseband signal which are in turn converted to digital baseband signals by the A to D convertor. DC offsets in the baseband signals are removed by high pass filtering prior to demodulation. Tracking enables the baseband signals to be maintained at a centre frequency of substantially zero hertz, while signal strength at this frequency is minimized or mulled before the DC offset filtering. Information which might otherwise be removed by the filtering is thereby retained in the baseband signals, which are relatively less distorted.