Abstract: A cellular wireless packet data communication system containing transmit-only endpoint devices which transmit to receive-only base stations. The system is configured to allow for large area coverage (e.g., a metropolitan area) with far fewer number base stations than are required with conventional two-way cellular systems. The base station coverage areas are configured to overlap, allowing for reception of packets at multiple base stations. A data concentrator resolves redundantly received messages. The network is configurable as a WAN, a LAN, or a combination of the two. Novel modulation techniques (e.g., a 16QAM submodulation together with a 7FSK modulation) are used such that low cost components can be used in the transmitters and receivers while achieving outstanding probability of success performance. The endpoint devices are battery operated and accordingly, are designed for low power consumption and multi-year battery life.

Abstract: A method utilizing intentionally generated in-band frequency harmonics to compensate for frequency error and frequency drift in a voltage controlled oscillator of a receiver, thereby eliminating the frequency synthesizer and RF divider required in conventional designs. The method includes modulating the intentionally generated frequency in a predetermined manner so that a receiver can identify the intentionally generated frequency and includes the use of plural frequency harmonics for use in a curve fitting technique to correct frequency error in the voltage controlled oscillator.

Abstract: A system and method for receiving direct sequence spread spectrum transmissions with both chip code and frequency uncertainty including a parallel frequency acquisition technique for increasing receiver sensitivity and increasing process gain while reducing a preamble duration required for spread spectrum acquisition. The system and method include techniques for reducing effects of jamming and impulse noise on receiver performance via enhanced antenna diversity by constructively combining received signals. Further, techniques are provided which compensate for chip code alignment drift, providing an associated transmitter maintains carrier and chip code coherence, by comparing received signal energies at varying chip code alignments. These techniques enable the use of lower cost frequency setting crystals in both the receiver and transmitter as well as provide for system operation over a wider temperature range.

Abstract: A method utilizing intentionally generated in-band frequency harmonics to compensate for frequency error and frequency drift in a voltage controlled oscillator of a receiver, thereby eliminating the frequency synthesizer and RF divider required in conventional designs. The method includes modulating the intentionally generated frequency in a predetermined manner so that a receiver can identify the intentionally generated frequency and includes the use of plural frequency harmonics for use in a curve fitting technique to correct frequency error in the voltage controlled oscillator.

Abstract: A method, apparatus, computer-based product and system employs a digital receiver (or transceiver) to receive, digitize and process a direct sequence spread spectrum signal using efficient, low-cost digital signal processing components. A radio front end portion of the receiver receives and digitizes the signal, and a digital signal processing portion downconverts and despreads the signal by applying a pseudorandom noise (PN) code, used at a transmitter to spread a data signal contained in the direct sequence spread spectrum signal, to the received signal. In order to initially align, and maintain alignment of, the PN code with the direct sequence spread spectrum signal, a timing and state control mechanism is included that provides time reference correction information to the signal processing components of the receiver.

Abstract: A method for improving a radio location system based on time-of-arrival. Time-of-arrival radio location systems are limited in ultimate accuracy by signal-to-noise ratio and by the time varying multipath environment in which they must operate. These systems time stamp some feature of an arriving signal, from a transmitter, in order to calculate a range or a hyperbolic line-of-position. Some feature of the received signal must be identified which can provide repeatable readings, in order for a time-of-arrival system to be reliable. The present invention teaches techniques which maintain a high signal-to-noise ratio while identifying a feature of the received signal which is least affected by multipath. The technique uses correlation peak/envelope information to estimate the leading edge of the correlation function, then enhances discrete samples at the leading edge of the correlation function to yield high signal-to-noise ratio readings.

Abstract: An enhanced frequency-agile radio for avoiding undesired signal energy, based on a prediction, by scanning an available radio spectrum, measuring a receiver output, identifying an occupied portion of the available spectrum, predicting a level of undesired signal energy in a future scan, and storing the prediction.

Abstract: A wireless alarm system using spread spectrum transmitters, fast frequency shift keying, spread spectrum receivers and computer with a display. The spread spectrum transmitter includes an oscillator coupled to a microprocessor with chip code generation means, preamble register, address register and data register. The spread spectrum receiver acquires synchronization of the spread spectrum signal using a microprocessor coupled to the quieting, signal strength or baseband output of the receiver, with a two step algorithm. The steps comprise achieving a coarse lock and a fine lock to the spread spectrum signal.

Abstract: A method for maintaining spread spectrum chip sequence synchronization, over arbitrary time periods, without the use of traditional closed loop strategies. The technique can be accomplished entirely in software or with the addition of a minimum of electronic components. The receiver periodically forces a chip code reposition optimization to jog the receiver-chip sequence into a high level of synchronization after some period of time in which the receiver's chip sequence alignment has run open loop with respect to the transmitter-chip sequence embedded in the received spread-spectrum signal. The reposition technique allows the use of very low cost crystals for the chip sequence generator time base in both receiver and transmitter, and also provides time cues in which to optimize time-of-flight radio position fixes.

Abstract: A frequency agile spread spectrum radio system which uses a frequency-agile receiver that adaptively learns which frequencies to avoid as being occupied or jammed. The transmitter sends redundant transmissions on widely separated pseudo-random carrier frequencies to overcome jammed channels. A coded preamble is used to provide a greatly enhanced hybrid form of Time Division Multiple Access/Frequency Division Multiple Access for co-existence and frequency re-use with nearby systems. Anti-jam margins of 60 to 90 dB can be inexpensively achieved, far exceeding that of traditional direct sequence systems. The receiver scans the radio spectrum, identifies occupied portions, stores information on these occupied portions, skips over the occupied portions for a set period of time while scanning for radio signals, detects a repetitive preamble code in a received radio signal, maintains the frequency of the received radio signal, and receives and decodes message data in the received radio signal.

Abstract: A frequency agile spread spectrum radio system which is capable of efficient frequency re-use and frequency sharing. The receiver adaptively learns which frequencies to avoid. The transmitter sends redundant transmissions on widely separated pseudo-random carrier frequencies to overcome jammed channels. A coded preamble is used to provide a greatly enhanced hybrid form of Time Division Multiple Access/Frequency Division Multiple Access for co-existence and frequency re-use with nearby systems. Anti-jam margins of 60 to 90 dB can be inexpensively achieved, far exceeding that of traditional direct sequence systems.

Abstract: A wireless alarm system using spread spectrum transmitters, fast frequency shift keying, spread spectrum receivers and computer with a display. The spread spectrum transmitter includes an oscillator coupled to a microprocessor with chip code generation means, preamble register, address register and data register. The spread spectrum receiver acquires synchronization of the spread spectrum signal using a microprocessor coupled to the quieting, signal strength or baseband output of the receiver, with a two step algorithm. The steps comprise achieving a coarse lock and a fine lock to the spread spectrum signal.

Abstract: A wireless alarm system using spread spectrum transmitters, fast frequency shift keying, spread spectrum receivers and computer with a display. The spread spectrum transmitter includes an oscillator coupled to a microprocessor with chip code generation means, preamble register, address register and data register. The spread spectrum receiver acquires synchronization of the spread spectrum signal using a microprocessor coupled to the quieting, signal strength or baseband output of the receiver, with a two step algorithm. The steps comprise achieving a coarse lock and a fine lock to the spread spectrum signal.

Abstract: A wireless alarm system using spread spectrum transmitters, fast frequency shift keying, spread spectrum receivers and computer with a display. The spread spectrum transmitter includes an oscillator coupled to a microprocessor with chip code generation means, preamble register, address register and data register. The spread spectrum receiver acquires synchronization of the spread spectrum signal using a microprocessor coupled to the quieting, signal strength or baseband output of the receiver, with a two step algorithm. The steps comprise achieving a coarse lock and a fine lock to the spread spectrum signal.

Abstract: A method and apparatus for radio position determination is provided including an unknown position transmitter for transmitting a radio wave having compensation for multipath, a plurality of base repeaters having a synchronized pulse for time reference, for receiving the radio wave emitted by the unknown position transmitter and for determining the relative times-of-arrival of the radio wave with respect to the synchronized pulse, and a central monitoring station coupled to the base repeaters for computing from the locations of the base repeaters and from the measured times-of-arrival, a coarse-position fix of the unknown-position transmitter. The system may include a mobile reference transceiver located within the coarse-position fix, for transmitting a reference signal, wherein the central monitoring station generates a differential position from the reference signal and the radio wave for guiding the mobile reference transceiver to the unknown position transmitter.