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 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 remote power meter monitoring system using spread spectrum transmitters, fast frequency shift keying, spread spectrum receivers and a computer. The spread spectrum transmitter uses a chip code generator, preamble register, address register data register and oscillator coupled to a microprocessor to transmit information in a direct sequence spread spectrum signal. The spread spectrum receiver acquires synchronization of the spread spectrum signal using a microprocessor to despread and detect the transmitted information, which relates to data from a power meter.

Abstract: A direct sequence spread spectrum (DSSS) DSP implementation technique utilizing a unique combination of multiple filters, transforms, despreading algorithm and spectral compression, all in a single coefficient set, providing a highly efficient system requiring relatively nominal computational hardware and software requirements. Reallocatable computational resources allow for frequency uncertainty in the transmitter, without the typical excessive noise bandwidth penalties. The present system further contemplates a unique energy detection algorithm for discerning spread spectrum while in the search mode, utilizing several discrete sampling data sets to increase signal strength, reducing noise, while changing the relative phase of the received chipping code with respect to the received signal. The spectral compression of the spreading sequence is achieved by representing the PRC as an array of two, complimenting fractional coefficients.

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: An enhanced system for calculating the Z-Axis, or relative height or altitude, of a radio beacon. The present invention uses a barometric pressure sensing device co-located with the radio emitter to transmit data representing relative altitude. To further enhance the Z-Axis determination, one or several barometric sensors, located at known heights, are positioned around the city to provide real time barometric data. This real time data is used to form a differential correction factor which is compared to the to the time varying barometric sensor co-located with the radio emitter, thereby yielding Z-Axis accuracies of up to one (1) foot. Since the altitude essentially becomes a "known", this information can also be used in the least squares fit algorithm to enhance the X and Y determination as well.

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: Method for determining the ranges between pairs of transceivers deployed underwater. According to a preferred embodiment, the transceivers transmit acoustic pulses to and receive acoustic pulses from other of such transceivers according to a coordinated schedule of individual transmission times and reception windows stored in each transceiver. Timers in each transceiver sequence the transceiver through its scheduled events. Periodic synchronization of all deployed transceivers keeps the transceivers synchronized. One- or two-way ranging between pairs of receivers is possible, with two-way ranging requiring only loose synchronization of transceivers. The preferred method of range determination includes a two-way range between pairs of transceivers, each transceiver transmitting pulses having preselected characteristics to the other on a different frequency channel.

Abstract: Apparatus and method for transmitting and receiving hydroacoustic pulses used to determine the spatial separations between pairs of such apparatus. According to a preferred embodiment, the apparatus transmits hydroacoustic pulses having a selected shape and frequency at specific times and also determines the time of arrival of received hydroacoustic pulses having a known shape and carrier frequency. Included is a transducer for converting the hydroacoustic energy received from a body of water into electrical energy and for converting electric pulses into hydroacoustic pulses which are then coupled into the body of water. Electric pulses having a selected shape and carrier frequency are digitally synthesized in response to a count comparator.

Abstract: For use with marine seismic streamers, a two-wire, multi-channel communication system capable of handling the high throughput necessary for effective communication between a central controller aboard a tow vessel and the many sensors deployed along the streamer. The central controller includes an intelligent modem with the capability of transmitting and receiving frequency-modulated message signals on one or more signal lines, such as conventional twisted-pair wires, over a number of individual inbound and outbound frequency channels. In the preferred embodiment, seventeen channels are spread over a frequency band ranging from about 20 kHz to 100 kHz, thereby making available for communication a bandwidth much wider than available in conventional single-channel streamer communication.

Abstract: Apparatus and method for transmitting and receiving hydroacoustic pulses used to determine the spatial separations between pairs of such apparatus. According to a preferred embodiment, the apparatus transmits hydroacoustic pulses having a selected shape and frequency at specific times and also determines the time of arrival of received hydroacoustic pulses having a known shape and carrier frequency. Included is a transducer for converting the hydroacoustic energy received from a body of water into electrical energy and for converting electric pulses into hydroacoustic pulses which are then coupled into the body of water. Electric pulses having a selected shape and carrier frequency are digitally synthesized in response to a count comparator.

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: Apparatus and method for transmitting and receiving hydroacoustic pulses used to determine the spatial separations between pairs of such apparatus. According to a preferred embodiment, the apparatus transmits hydroacoustic pulses having a selected shape and frequency at specific times and also determines the time of arrival of received hydroacoustic pulses having a known shape and carrier frequency. Included is a transducer for converting the hydroacoustic energy received from a body of water into electrical energy and for converting electric pulses into hydroacoustic pulses which are then coupled into the body of water. Electric pulses having a selected shape and carrier frequency are digitally synthesized in response to a count comparator.

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.

Abstract: The system includes a method and apparatus for transmitting a spread spectrum signal from each of a plurality of base stations. The spread spectrum signal has a predetermined timing and has a ground wave component and a sky wave component. The signal is transmitted with a repetition time at least as great as a maximum anticipated delay time of the sky wave component such that the ground wave component of the transmitted spread spectrum signal can be distinguished from the sky wave component. The signal is detected at each of a plurality of mobile stations and the timing of the detected signal is compared to a local timing signal. The phase difference between these signals is indicative of the range of the base station from the mobile station.