Abstract: A fleet vehicle navigation system for supplying driver specific information to the driver of a fleet vehicle includes a computing system, a short-range radio transceiver and at least one fleet vehicle. Once a driver is assigned to a fleet vehicle, driver specific information may be communicated between the computing system and fleet vehicle. Communication of driver specific information is triggered by the entry of the assigned fleet vehicle into a communication zone of the short-range radio transceiver. Driver specific information includes intended destinations of the driver, travel plans, vehicle settings and vehicle operational data.

Abstract: A vehicle navigation system that is capable of learning user habits/preferences, mistakes in a digital map database, and new roads that may have been added or constructed after release of the digital map database is disclosed. The vehicle navigation system monitors a driver's habits and updates a database to thereby cause the vehicle navigation system to have a preference for the driver's habits. The vehicle navigation system may also monitor the geographic position of the vehicle and allow the driver to update or change data contained in the digital map database if an error exists. The vehicle navigation system is also capable of learning new roads that exist that are not included in the road network map of the digital map database and is also capable of adding these new roads to the digital map database.

Abstract: A digitally trunked radio repeater system provides substantial improvements in timeliness and reliability. The mobile radio transceivers transmit channel requests on the control channel at 9600 bps. The mobile transceiver switches to a working channel in response to an assignment message received on the control channel. Message and transmission trunking capabilities are both present so as to maximize working channel usage without compromising channel access for high priority communications. Radios select between message and transmission trunking based on over-the-air signaling. During transmission trunking, called and calling receivers return to the control channel after each transmission (and called transceivers may be inhibited from transmitting) but grant higher priority to calls from the other transceivers being communicated with to ensure continuity over an entire conversation.

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: An extremely compact, full featured portable radio architecture conserves power by allowing a processor to sleep except when it needs to perform tasks. A lower power processor which acts principally as an interrupt controller but which performs other functions as well (e.g., tone decode, synthesizer lock monitoring, etc.) so the main processor can sleep as much as possible and yet is assured of being awoken promptly when its processing power is required. The resulting portable radio has extremely low power consumption (e.g., on the order of 75 milliamperes during trunked mode operation)--thereby permitting even a relatively small battery pack to provide nearly 8 hours of continuous operation. The portable radio with battery is small and lightweight enough to fit into a front shirt pocket.

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 single channel autonomous trunking ("SCAT") RF repeater transmits and receives on a single duplex RF channel. The repeater operates alternately in a control channel mode and in an assigned channel mode. Digital control channel signalling results in temporary assignment of the single channel for assigned channel signalling (e.g., mobile generated messages). A holdover time period following reversion of the channel to control channel signalling minimizes collisions and permits priority to be given to emergency communications. Low speed data subaudible digital signalling may be used to provide late entry capabilities.

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 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: 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 assignement 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 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: A digitally controller radio transceiver includes a housing including a front cover provided with a display port; a main controller board mounted within the housing; an optional display board attached to an interior surface of the front cover adjacent said display port, said display board electrically connected to said main controller board by a pressure fit connection; a removable display escutcheon plate mounted on an exterior surface of the cover, overlying the display port; and fastening means extending through the cover and connecting the display board to the display escutcheon plate. Removal or omission of the display board is automatically sensed by the radio transceiver's internal microprocessor which operates accordingly. In one embodiment the transceiver program store may be loaded via an external connector to customize the microprocessor instruction code for the presence or absence of a display.

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 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: Cooperation between two repeater transceivers of a radio trunking system causes a mobile radio transceiver to join or rejoin ongoing communications. To join ongoing communications, a radio transceiver attempts to acquire a free repeater communications channel by transmitting call signalling identifying a group of transceivers to be contacted. If the group to be contacted is already communicating on another repeater communications channel, the calling radio transceiver is forced to leave the communications channel it is trying to acquire and to begin scanning communications channels in search of call signalling identifying it. Meanwhile, the repeater permitting the ongoing communication interrupts the ongoing communications briefly and transmits the call signalling identifying the group of transceivers to be joined (including the radio transceiver which is to join the ongoing communications).

Abstract: An energy efficient lighting unit is described designed for functional similarity to the incandescent light used in the home. The lighting unit utilizes a metal vapor arc lamp as the main source of light supplemented by a standby filamentary light source. The lighting unit includes means for converting 60 hertz ac to dc, and a dc energized operating network containing a three transistor switch. The transistor switch is used to provide dc and low frequency (120 Hz) energization to the filament, and high frequency energization for both filament and arc lamp. The high frequency energization, which starts and transitions the arc lamp, is discontinued after the arc lamp is started. In the final run state, the arc lamp, which is serially connected with the filament across the dc supply, is ballasted by the filament.

Abstract: An energy efficient lighting unit is described designed for functional similarity to the incandescent light used in the home. The lighting unit utilizes a metal vapor arc lamp as the main source of light supplemented by a standby filamentary light source. The lighting unit includes means for converting 60 hertz ac to dc, and a dc energized operating network containing a three transistor switch. The transistor switch is used to provide dc and low frequency (120 Hz) energization to the filament, and high frequency energization for both filament and arc lamp. The high frequency energization, which starts and transitions the arc lamp, is discontinued after the arc lamp is started. In the final run state, the arc lamp, which is serially connected with the filament across the dc supply, is ballasted by the filament. The transistor switch is controlled in its operation by an integrated circuit.

Abstract: The present invention relates to a threshold amplifier suited to integrated circuit fabrication of a process employing CMOS technology. The threshold amplifier is designed to sense current producing a first or a second logic level as a function of a current threshold. The amplifier comprises a p-channel device and a n-channel device serially connected across the bias supply. The gate to source voltages of the two devices are respectively controlled by a diode connected p-channel device similarly serially connected across the bias supply with a diode connected n-channel device, the source of the latter being returned to ground via a current carrying resistance also in the second series path. The output level which is taken at the drain inter-connection between the devices in the first series path depends on the relative conductivity of the two devices which is in turn affected by the induced voltage drop in the source connected resistance in the second series path.

Abstract: The present invention relates to a pulse generator for use at a selected frequency near 100 Khz and having a predetermined duty cycle (typically 20%). The pulse generator is designed for integrated circuit fabrication using a CMOS process. The design utilizes a ring oscillator whose frequency is varied by external adjustment of a single resistance and which utilizes a gating stage responsive to electrical conditions in at least two stages of the ring oscillator to establish the desired duty cycle. The duty cycle may also be adjusted, as by the inclusion of optional stages in the ring oscillator. The design features a low power consumption, and high temperature stability of frequency and duty cycle.