Abstract: A method for sending messages from a particular device to one or more other devices communicants (300) uses the relative geographic location of the targeted devices as addressing criteria. The particular device forms or joins a network of potential communicants, and exchanges information to determine their relative geographic location with respect to that of the particular device (310, 320). The relative geographic location is preferably defined by a directional component and a range component. The communication device then selects for communication those devices that meet specific criteria, such as a specific direction and range, and transmits a message to the selected devices (330, 332, 334, 336).

Abstract: A method for managing a task list utilizes location-based filtering to generate a reminder to a user of a communication device to perform an outstanding task. The communication device is provided with information on an outstanding task associated with a particular site and at least one proximity parameter for triggering a reminder for performing the outstanding task at a particular site (420). The communication device obtains geographic location information for the particular site and obtains information on its current location (430, 440). The device determines whether it is located within an area in which the outstanding task can be completed, which area is defined by a boundary established based at least in part on the geographic location of the particular site, and on the proximity parameter specified (450).

Abstract: A contention resolution method includes the steps of determining a contention has occurred and requesting contention resolution from radios in the system (604). Radios in the system receive the request and do not transmit in the next control frame (606). Group leader radios (202, 208 and 214) transmit the identification code they were able to demodulate in the previous frame to the master radio (608). The master radio (212) receives the information from the group leaders and transmits a control-channel access message to one of the contending radios (610).

Abstract: A method and apparatus for encoding and decoding signals using code position modulation (CPM) in a communication system. The encoding method includes storing an N-chip pseudo-random noise sequence, such as an m-sequence, in a circular shift register and circularly shifting it to obtain a shifted m-sequence. The shifted m-sequence is compared to an m-bit symbol corresponding to the k bit information value. If the shifted m-sequence and the m-symbol match, the shifted m-sequence is output as the N-chip CPM sequence. Alternatively, the m-symbol is used as an initial condition for a pseudo-noise sequence generator. The corresponding decoder stores an N-chip m-sequence in a circular shift register and a correlates shifted version of the m-sequence with a received N-chip CPM sequence. When a peak in the correlation value is detected, an m-bit field is retrieved from the circular shift register and mapped back to a k-bit information value.

Abstract: A method and apparatus for DS-CDMA communication having improved timing resolution. In the transmitter, a signal spread by a first sequence of pulses is generated with pulse shape given by p ⁡ ( t T c ) , where t is time and Tc is the chip period or pulse width. The pulses have an auto-correlation function q ⁡ ( t T c ) . In receiver, a second sequence of pulses with pulse shape given by p ⁡ ( t T c ) is generated.

Abstract: An electronic tag assembly (100) includes a substrate (102) having an antenna pattern (104, 106) disposed thereon, an integrated circuit die (108) having electrical interface terminals (204, 206) that directly contact or interface with the antenna pattern (104, 106), and electrically non-conductive adhesive (202) interposed between the substrate and the integrated circuit die (108) that secures both together, and that maintains the integrity of the electrical interface. Preferably, a clamping force is exerted on the integrated circuit die (108) to maintain contact between the electrical terminals (204, 206) and the antenna pattern (104, 106) while the non-conductive adhesive (202) is being introduced.

Abstract: A feedforward amplifier (150) according to the present invention uses a direct coupling of an amplifier stage (158) with the amplifier's load (RL). The main amplifier (202) is coupled through a transmission line (210) to the load. This direct coupled amplifier stage (158) is driven by a signal that induces a very low impedance in parallel with the load to the error signal, but appears as an open circuit to the desired signal so that the desired signal from the main amplifier is substantially unaffected.

Abstract: A method and apparatus for direct sequence spread spectrum communication having low complexity. In the transmitter, the data bit is spreaded by a code sequence, a reference code is interleaved with the code sequence, and together they are transmitted by the transmitter. The corresponding receiver recovers the data signal from the received signal by transforming the received signal to a complex base band signal and differentially decoding the base band signal at the chip level. The spreaded signal is despreaded by the chip-level differential operation, thus eliminating the decorrelation operation, and so significantly reducing the cost of the overall system. Furthermore, this system is very robust to any carrier frequency drift since the chip-level differential operation is used, thus releasing the reference clock or crystal requirements, and so further reducing the cost of the system.

Abstract: A digital frequency synthesizer includes a clock which produces a clock signal oscillating at a fixed frequency and a delay line which receives the clock signal and which produces therefrom a plurality of phase shifted clock signals oscillating at the fixed frequency. Each phase shifted clock signal is shifted in phase with respect to the clock signal and with respect to the other phase shifted clock signals. A look-up table receives an address value related to an ideal phase shifted clock signal oscillating at the fixed frequency and outputs a tap address related to the address value. A selection circuit receives the plurality of phase shifted clock signals and the tap address and outputs one of the phase shifted clock signals in response thereto. A sampling circuit samples at least a portion of the one phase shifted clock signal output by the selection circuit and outputs the sampled portion to form at least a part of an oscillator signal having a desired frequency.

Abstract: A system for locating a number of devices (112-130) by measuring signals transmitted between known location devices (112-118, 134-138, 214-218, 224-228) and unknown location devices (120-130, 222), and signals transmitted between pairs of unknown location devices (120-130,222), entering signal measurements into a graph function that includes a number of first sub-expressions, a number of which include signal measurement prediction sub-expressions, and have extrema when a predicted signal measurement is equal to an actual signal measurement, and optimizing the graph function.

Abstract: A digital tone generator (1110) includes a digital signal generator (1138) which generates a digital waveform data sequence which is representative of a tone having a predetermined waveform, and an adaptive duty cycle pulse-width modulator (1132) which is responsive to the digital waveform data sequence for generating an an adaptive duty cycle period characterized by a pulse-width modulated digital tone signal having a variable frequency and duty cycle which is generated by selecting a variable number of clock pulses of a predetermined reference clock (31).

Abstract: An orthogonal latch assembly includes a latching member 300 and a catch 400 having a first wedge shaped section 202 and a second wedge shaped section 204. The first wedge shaped section 202 enables engagement of the catch 400 with latching member 300. The second wedge shaped section 204 enables disengagement of the latching member 300 from the catch 400.

Abstract: A digital demodulator (100) includes a differentiate and cross multiply stage (102) and a plurality of filter/decimator stages (106, 112, 118 and 108, 114, 120 and 110, 116, 122) that accept both multiple baud rates and multiple modulation deviation frequencies, and that provide a common frequency data stream at their respective outputs. One of said filter/decimator stages is coupled to a primary filter (124) which is followed by a box filter (134). The box filter (134) improves the overall filter response and provides notches at a specified frequency (e.g., 4800 Hz) and its harmonics. Demodulator (100) provides improved sensitivity without the need for any circuit trimming. The filter stages (e.g., 106, 112, 118; 108, 114, 120; and 110, 116, 122) used in demodulator (100) have been optimized to eliminate the need for costly multipliers.

Abstract: A digital tone generator (1110) includes a digital signal generator (1138) which generates a digital waveform data sequence which is representative of a tone having a predetermined waveform, and a pulse-width modulator (1132) which provides an adaptive duty cycle period (622, 630) which is responsive to the digital data waveform data sequence for selecting clock pulses of a number sufficient to generate a pulse-width modulated digital tone signal. The digital tone generator (110) can also include a low pass filter (36) which processes the pulse-width modulated digital tone signal to generate an analog tone signal. The digital waveform sequences generated by two digital tone generators (38, 40) can be digitally added by a digital adder (28) to provide a composite tone data signal, which can be processed by the adaptive pulse-width modulator (700) to produce a pulse-width modulated tone signal representative of a DTMF tone.

Abstract: A method (200) for protecting receiver circuitry from high radio frequency (RF) overload voltages input to the antenna by monitoring power level and received RSSI level includes detecting (209) inside the receiver any reverse RF power on an antenna (201) connected to the receiver. The detected RF power is converted (211) to a direct current (DC) voltage. The DC voltage is compared (213) against a predetermined reference voltage. A switch (205) is than actuated (219) to disconnect the antenna if the DC voltage exceeds the reference voltage. Moreover, a radio signal strength indication (RSSI) is detected (221) based upon a received on-channel signal and is compared (223) to a first reference voltage. A secondary RF attenuator is actuated (225)if either the RSSI is lesser than the first reference voltage (223) or greater than a second reference voltage(227) for reducing input signal strength from the antenna.

Abstract: A modulated signal, having a varying magnitude signal envelope, is conditioned, such as to facilitate amplification (500). Minimum values are determined values for portions of the signal envelope (520, 530), and a window expansion function applied to scale each portion of the signal envelope having a minimum value below a particular threshold, such that each scaled portion has a new minimum value of at least the particular threshold (535, 540, 550, 555).

Abstract: A communication device (10) couples a microphone (12) to a modulator (22) that modulates a microphone signal via a transmission medium (14) having an antenna element (18) for radiating the modulated electromagnetic signal. The communication device also has a housing (36) incorporating device circuitry that is linked to the microphone (12) via the transmission medium (14).

Abstract: A digital tuning circuit (100) for a filter (120) has a filter input and a filter output and employs a switchable element array (122). The filter includes a tuning signal generator (104) that generates a tuning signal (106) that is delivered to the filter input and a clock circuit (102) that generates a periodic stream of pulses. The digital tuning circuit includes a delay circuit (110), a phase comparator (130) and an integrating up-down counter (140). The delay circuit (110) is responsive to the tuning signal generator (104) and delays the tuning signal (106) by a predetermined amount corresponding to the nominal delay through the filter (120). The integrating up-down counter (140) counts pulses in a first direction when the phase comparator (130) generates the first value and counts pulses in a second direction, opposite from the first direction, when the phase comparator (130) generates the second value.

Abstract: A tunable inductor circuit and phase tuning circuit utilizing a tunable inductor circuit for dynamically controlling signal phase delay in RF/Microwave Circuits and related applications. The tunable inductor includes an inductor and a voltage variable capacitor connected to each other. The tunable inductor and voltage variable capacitor can be connected to each other in parallel or in series. The phase tuning circuit includes at least one tunable inductor circuit and at least one voltage variable capacitor coupled to the at least one tunable inductor circuit, wherein the at least one tunable inductor circuit and the voltage variable capacitor are responsive to control signals to alter a tuning characteristic of the phase tuning circuit.

Abstract: Automatic assistance to unaided voice communication is provided by activating and deactivating a wireless communication link as needed (300). A communication device, associated with a particular individual, monitors to determine whether unaided communication occurring with another individual is satisfactory according to a predetermined criteria (310, 320, 330). The communication device automatically switches to provide aided communication, when the unaided communication is not satisfactory. Preferably, an open communication link is established between the communication device and one associated with the other individual when sound reception characteristics or separation characteristics do not meet a particular criteria (340, 350, 360, 370).