Abstract: In a wireless communication system with an air interface comprising a plurality of bursts, a plurality of bursts is defined. Each burst comprises a field (300) embedded within the burst. The field is one of a synchronization field (300?) and a signaling field (300?). When the field is a synchronization field, a position of at least one subsequent burst comprising the signaling field is defined, and a position of at least one subsequent burst comprising the synchronization field is defined.

Abstract: The present invention relates generally to the field of frequency modulation, and in particular to dual port frequency modulators. The present invention provides a frequency modulator comprising a phase lock loop circuit (108) for receiving and modulating a carrier signal according to the low frequency component of a modulating signal, the phase lock loop circuit comprising a voltage controlled oscillator (118) for outputting a modulated carrier signal and a loop filter (116) for outputting a steering voltage to the VCO, the VCO having a tank circuit (120) comprising a voltage controlled capacitance (VAR1). The frequency modulator also comprises an external voltage controlled capacitance (122) which is arranged to modulate its capacitance according to a high frequency component of the modulating signal, the second voltage controlled capacitance being coupled to the tank circuit.

Abstract: A method for improving fault detection and exclusion of a GPS receiver is provided. The method determines pseudorange measurement residuals of tracked signals, divides the signals into two groups based on whether each signal has a higher or lower probability of being a failure, and estimates a residual bias using only the lower probability group of signals. The method further removes the residual bias from all calculated residuals, and compares each range residual to one of three different thresholds. A tighter threshold is applied to positive residuals of the group of signals with higher failure probability than to the group of signals with lower failure probability. A further tighter threshold is applied to negative residuals of the group of signals having higher failure probability. The method then determines PVT values of the GPS receiver utilizing range measurements of signals whose measurement residual magnitudes are less than their corresponding threshold values.

Abstract: When a roaming communication unit (15) requires an updated encryption key to ensure continued secure communications with other communication units of its home system, it transmits a rekey request to a base site (16) for the system (14) in which it has a presence. The latter provides the rekey request to a key management facility (17) for that system. This key management facility, in turn, provides the rekey request to the key management facility (13) for the roaming communication unit's home system (10). The latter then forwards a rekeying message that includes a rekeying encryption key to the roaming communication unit (15) with the second system's key management facility (17) acting as an intermediary. In a preferred embodiment, the rekey message is encrypted using an encryption key that is presently available to the roaming communication unit but not to the second system's key management facility.

Abstract: A method and apparatus for measuring current by a single sensor for two motor phases driven by first and second set of switches to drive respective first and second phases of a motor under control of PWM signals. A first step 100 includes reading a duty cycle of each winding drive current. A next step configures 104, 110, 114, 116, 118 the PWM signals to provide at least one timing window wherein at least of one of the windings of the motor is being driven while the other winding is not being driven, and to provide a relative timing offset of approximately one-half cycle between the pulse width modulation signals driving a first winding and a second winding of the motor. A next step 90 includes gating the switches with the configured PWM signals. A next step 95 includes sampling the current of the at least one of the windings with a single sensor.

Abstract: A first image (200) of a transmitted signal is detected within a received signal containing a plurality of images of the transmitted signal. This is accomplished by detecting a second image (210) of the transmitted signal. A set of characteristics of the second image of the transmitted signal is determined, and subsequently used to detect the first image (200) of the transmitted signal.

Abstract: In a time division multiple access system, a subscriber listens to an assigned channel (300) and an alternate channel (302) until a location of reverse channel signaling is determined for the assigned channel. The subscriber also obtains a fixed periodic rate (304) for the reverse channel signaling. Based on the fixed periodic rate, the subscriber selectively listens to the alternate channel to receive reverse channel signaling while transmitting information on the assigned channel. The base repeater, however, selects the fixed periodic rate for reverse channel signaling and transmits the reverse channel signaling at the fixed periodic rate to the transmitting subscriber. If the base repeater receives a burst belonging to a superframe and determines that any burst in the superframe will collide with the reverse channel signaling, the base repeater buffers any received burst in the superframe and transmits the buffered bursts at a subsequent time.

Abstract: Disclosed herein are two techniques, neutral point switching and field voltage boost, that will increase the output of today's 12 volt automotive electrical systems in vehicle idle conditions solely by the addition of circuitry. Neutral point switching enables the flow of a third harmonic current, which does not normally flow at low speeds, but only at high speed. Boosting the field voltages can be obtained by integrating a field voltage boost circuit and voltage regulator to increase the field voltage, and consequently the field current, above the level obtained from the battery. Furthermore, the transient response of the alternator to a change in load is improved by temporarily increasing the field voltage above the level needed to sustain the load. These two techniques are compatible, and thus may be implemented together, or may be implemented independently. No changes to a standard alternator are required to accommodate the proposed additional circuitry.

Abstract: An accelerometer or accelerator switch and its method of manufacture are disclosed. The device is fabricated from two substrates: a top substrate having a moveable mass, and a bottom substrate having at least one conductive plate. The top substrate is preferably a SOI substrate, and the mass and its suspending beams are formed in the silicon layer under which the insulator layer has been removed. The bottom substrate is preferably oxide. In one embodiment, the capacitance is formed using the mass as the first capacitor plate the conductive plate as the second plate. As the mass moves, the capacitance is detected to indicate the magnitude of the acceleration, or whether acceleration is above or below a threshold indicting an open or closed switch. The beams which suspend the mass can be serpentines, which make the device compact and render the mass more flexible. Alternatively, the bottom conductive plate can be split into two plates each coupling to the mass.

Abstract: Disclosed are methods for adjustment values. In one embodiment, a cumulative adjustment value is provided in memory, an inbound signal is transmitted to a base station during a random access opportunity, and a relative adjustment value is received from the base station. Then, the relative adjustment value is summed with the cumulative adjustment value to create a new cumulative adjustment value which is stored in the memory. Finally, a subsequent inbound signal is transmitted using the new cumulative adjustment value during a reserved access opportunity.

Abstract: A portable communication device (100) is capable of coupling to a two-way radio (102) via an interface. The portable communication device is capable of selectively functioning as an accessory for the two-way radio and as a standalone communication device when coupled to the two-way radio.

Abstract: A signal that has been received over a first channel is estimated. A set of channels that the signal will be received over is determined. Based on the estimated signal and the set of channels, the signal is removed from a plurality of signals received over a second channel.

Abstract: A transmitting device (100) transmits a first packet, comprising a second encryption vector, that is encrypted using a first encryption vector. The transmitting device transmits a second packet that is encrypted using the second encryption vector if an acknowledgement message is received within a predetermined time after transmitting the first packet; otherwise, the first packet is re-transmitted. Upon receipt of the first packet, a receiving device (102) decrypts the first packet using the first encryption vector and transmits the acknowledgement message. Upon receipt of the second packet; the receiving device attempts to decrypt a portion of the second packet using the first and second encryption vectors. If the portion of the second packet was successfully decrypted using the first encryption vector, the receiving device re-transmits the acknowledgement message for the first packet; otherwise, it transmits an acknowledgement message for the second packet.