Abstract: A transceiver employing a steerable phased-array antenna includes a modem architecture in which signals from each antenna element in the array are independently processed down to the individual baseband channel level, and digital beamforming is performed at baseband. The data rate reduction from IF to baseband permits parallel signal data from multiple antenna elements to be time multiplexed and serially processed at acceptable data rates at baseband with minimal modem hardware requirements. Both for transmit signal modulation and received signal demodulation, the computation of carrier tracking, automatic gain control (AGC)/power-control, and beamforming are shared by the same processing circuitry for all channels when performed at baseband. The resulting baseband circuitry is only incrementally larger than that required for carrier tracking and AGC alone, yet accomplishes independent beamforming for each antenna element on each user channel.

Abstract: A communications system operating in one or more frequency bands of various number of channels per band (for a total of N channels), and a novel transceiver for receiving these multiple bands of signals. The transceiver comprises an antenna and RF front end for each said band, a separate RF to IF downconverter for each said band. The IF for each band is centered at a succession of frequencies Fo such that the spectra for each band are non-overlapping, with the center frequencies. Analog-to-digital converter sampling rate is chosen such that one band is centered at baseband, and one or more other bands are centered at a specific relationship with the sampling rate such that each band is individually downconverted to baseband by appropriate selection of tap weight multiplying sequences (such as alternating +/− sequence for the case of Fo equal to one-fourth the sampling rate). An analog-to-digital converter converts analog signals to digital signals from the combiner.

Abstract: A parallel digital matched filter is constructed which performs numerous simultaneous correlations of a received spread spectrum signal against various replica offsets of its spreading sequence. This allows for the rapid acquisition of the received signal code phase, and subsequent handoff to tracking for a multi-channel receiver. A novel matched filter computational architecture is utilized, in which common digital arithmetic elements are used for both acquisition and tracking purposes. As each channel is sequentially acquired by the parallel matched filter, a subset of the arithmetic elements are then dedicated to the subsequent tracking of that channel. This process is repeated, with the remaining available arithmetic elements accelerating the acquisition of the next channel, and so on, until all resources are allocated as tracking channels. Additionally, multiple data inputs and delay lines are present in this architecture, and are available for processing at each arithmetic element.

Abstract: A spread-spectrum demodulator architecture is presented which utilizes parallel processing to accomplish rapid signal acquisition with simultaneous tracking of multiple channels, while implementing an integrated multi-element adaptive beamformer, Rake combiner, and multi-user detector (MUD). A matched filter computational architecture is utilized, in which common digital arithmetic elements are used for both acquisition and tracking purposes. As each channel is sequentially acquired by the parallel matched filter, a subset of the arithmetic elements are then dedicated to the subsequent tracking of that channel. Additionally, multiple data inputs and delay lines are present, connecting the sampled baseband data streams of numerous RF bands and antenna elements with the arithmetic elements. The matched filter/despreader processing is virtually independent of channel origin or utilization; e.g., CDMA users, RF bands, beamformer elements, or Rake Fingers.

Abstract: A spread-spectrum demodulator architecture is presented which utilizes parallel processing to accomplish rapid signal acquisition with simultaneous tracking of multiple channels, while implementing an integrated multi-element adaptive beamformer, Rake combiner, and multi-user detector (MUD). A matched filter computational architecture is utilized, in which common digital arithmetic elements are used for both acquisition and tracking purposes. As each channel is sequentially acquired by the parallel matched filter, a subset of the arithmetic elements are then dedicated to the subsequent tracking of that channel. Additionally, multiple data inputs and delay lines are present, connecting the sampled baseband data streams of numerous RF bands and antenna elements with the arithmetic elements. The matched filter/despreader processing is virtually independent of channel origin or utilization; e.g., CDMA users, RF bands, beamformer elements, or Rake Fingers.

Abstract: A digital positioning system using digital AM and FM radio stations for use in the environment of a plurality of digital AM and FM (AM/FM) radio stations which comprises a customer service center and a reference station which regularly and passively receives signals from all local digital AM/FM stations and measures variations in key parameters of frequency and wavelength thereof and provides AM/FM correctional data signals corresponding to each AM/FM station frequency and wavelength variation to the customer service center. The customer service center is adapted to provide the AM/FM correctional data signals to each of the digital AM/FM radio stations for insertion into ancillary digital data broadcast from each digital AM/FM radio station.

Abstract: Positioning system for locating a mobile body comprising a plurality of earth based spread spectrum (SS) broadcasting stations arranged geographically in a cellular pattern. Each SS broadcasting station include a modulator providing a channel signal structure which is substantially orthogonal with respect to adjacent stations in the cellular pattern, each channel signal including navigation beacon data including a unique beacon identification, station latitude and longitude, time.sub.-- slot and phase characterizations and selected parameters of adjacent stations. In one embodiment, each modulator provides a chirped SS signal in which the navigation beacon is a frequency tone that is repeatedly swept over a selected frequency band for each station. In a further embodiment, each modulator provides a GPS like direct sequence SS signal in which the navigation beacon is a PN coded broadcast.

Abstract: An existing TDRSS satellite communication system is incorporated, together with low-power ground-based remote transceivers of special design, and additional beamforming and steering elements at the ground terminals, to make possible digital communication between low power field transceivers and satellite ground terminals. The satellite communication system transmits to its ground terminals a composite signal, comprising amplified, phase-coherent signals received by an array of broad-coverage antennas on the satellite. The field transceiver transmits a pseudonoise coded signal spread across all or a portion of the satellite's receive bandwidth. At the ground terminals, the downlinked composite signal is processed by a beamformer to define a narrow, high-gain beam between the satellite and low-power transceiver. Signal processing gain and beamformer gain in combination serve to elevate the received, demodulated signals well above the noise level at the receiver.

Abstract: An information broadcast system having a broadband broadcast system selected from cable and satellite for broadcasting requested information from a selected information source, including the Internet, to one or more selected subscriber stations includes an independent backhaul channel for communicating information request signals from a subscriber station to one or more central processing stations. The system includes a data broadcast station for transmitting requested data from the selected data source and central station via the data broadcast station to the one or more selected subscriber stations. The high-data rate broadcast station forwards requested data from a data source to the data broadcast station. A backhaul satellite communication system, independent of the broadband broadcast system, has a backhaul satellite ground terminal for coupling information request signals from backhaul satellite communication system to high data broadcast station terminal.

Abstract: The satellite radio communication system of this invention provides communication between one or more service centers and an ensemble of fixed and mobile user terminals. One or more earth orbiting satellites are provided with each satellite having transmitter forming a down-link channel which is slow frequency hopped, and a multi-beam antenna system with a single channel per beam to time division multiple broadcast signals to all user terminals covered by each said beam, respectively. Each user terminal includes a transceiver for receiving a down-link channel broadcast from the one of said beams in whose path it lies, and a return link comprised of a dedicated narrow band broadcast channel with slow frequency hopping of down-link channel. There is a fixed set of frequencies through which the frequency hopping is carried out, with the plurality of fixed and mobile user terminals using the same set of frequency hopping frequencies.

Abstract: A scrambled analog signalling system having a source of analog signals to be sent to a receiving device is comprised of a multiple stage charge coupled device (66) having analog signal input terminals connected to receive analog signal samples from said source of analog signals. The multiple stage charge coupled device having N stages, corresponding stage taps, and an input clock signal. A shuffling circuit (68) having a first input connected to the N stage taps for receiving the analog signal samples and second input for receiving a random seed (67) signal to cause a random reordering of incoming analog signal samples, a source of random seed signals connected to the second input, and an output device (72) connected to receive a stream of the analog signal samples which have been shuffled according to a mapping code carried by the random seed signal.

Abstract: A satellite communication system including one or more satellites in geosynchronous orbit and inclined at a predetermined angle greater than 0.degree. relative to earth, a preferred angle being about 28.5.degree. for full earth coverage, there is a constellation of satellites. Each satellite has a multi-element phased array antenna and transmit and receive circuits selectively connected to said multi-element phased array antenna for providing spatially discriminated spot radiation beams on the earth's surface, and a steerable spaced/ground antenna and transmitter-receiver circuitry connected thereto. At least one gateway ground terminal having means for performing all spacecraft command and control, including uplink phasing of said phased array antenna for directive satellite transmissions to desired user locations.

Abstract: A data-in-voice modem is disclosed using charge coupled devices. Unique features include: (1) Baseband-to-IF upconversion to enable CCD-based demod/processing; (2) All analog (no analog-to-digital A/D required); option for post-CCD A/D; (3) Additional on-chip functions; (4) Stand-alone, CCD-based high-rate modem over telephone lines; and (5) CCD-based cable-tv/multimedia processing, via baseband-to-IF upconversion, followed by IF-sampled CCD processing.

Abstract: An existing TDRSS satellite communication system is incorporated, together with low-power ground-based remote transceivers of special design, and additional beam forming and steering elements at the ground terminals, to make possible digital communication between low power field transceivers and satellite ground terminals. The satellite communication system transmits to its ground terminals a composite signal, comprising amplified, phase-coherent signals received by an array of broad-coverage antennas on the satellite. The field transceiver transmits a pseudonoise coded signal spread across all or a portion of the satellite's receive bandwidth. At the ground terminal, the downlinked composite signal is processed by a beamformer to define a narrow, high-gain beam between the satellite and low-power transceiver. Signal processing gain and beamformer gain in combination serve to elevate the received, demodulated signals well above the noise level at the receiver.

Abstract: A radio transmitter having a source of first signals for radio transmission, includes a modulator for modulating the first signals on an intermediate carrier frequency second signal to produce a third signal. A charge coupled device (CCD) is connected to receive and process the third signal in the absence of digital waveform shaping and digital-to-analog conversion. The CCD has a sampling rate which is a multiple of the intermediate carrier frequency second signal to provide aliased fourth signal components that are spectrally spaced in accordance with the multiple and provide upconversion to a fifth signal. A bandpass filter receiving the fifth signal is centered around a selected aliased signal component and a power amplifier/antenna means coupled to receive said selected aliased component for transmission. In a preferred embodiment, the multiple is 4. Moreover, the tap weights of the CCD are selected to provide wave shaping of the aliased fourth signal components.

Abstract: A location determination system and method in which mobile receiver units are in an area of at least three fixed commercial television stations, each television station broadcasting standard television signals, including horizontal, vertical and chrominance burst synchronizing signals. The standard television signals from selected ones of said television station are received at the mobile receiver unit and the times of arrival synchronizing signals of the selected ones of the television stations, respectively, are measured to produce mobile receiver unit signals corresponding thereto. A fixed reference station receives the television signals and detects any frequency and wavelength drift in the standard television signals from each of the fixed commercial television stations, respectively, and produces reference receiver correction signals.

Abstract: This invention relates to a novel receiver architecture, the Charge-Coupled-Device Integrated Receiver (IR), which simplifies electronic circuitry requirements and reduce baseband processing rates through efficient signal processing. The focus of this receiver's design is its use of Charge-Coupled-Device (CCD) technology. By using CCD's, in conjunction with other key technologies, to implement the signal processing techniques disclosed herein, it is possible to provide a receiver that is suitable for a wide range of applications (e.g., communications, sonar, radar, etc.). Information is presented which outlines the fundamental receiver architecture that is appropriate for a wide range of commercial services (e.g., AMPS, NAMPS, Digital Cellular, GSM, PCS, ISM, CT1, CT2, etc.) Furthermore, tile versatility of this architecture makes it suited for uses ranging from simple AM/FM receivers to complex high-order modulation TDMA/CDMA receivers.

Abstract: The present invention relates to a no outage GPS/AM position finding system wherein a GPS system having a plurality of satellites transmits time and location data over radio frequency signals to enable a mobile GPS receiver station on the ground to determine its position, and a cellular telephone is carried with the mobile GPS receiver, traveling in range of a plurality of conventional ground based amplitude modulated (AM) transmitters for transmitting AM signals. Each mobile GPS receiver station includes phase detection means for simultaneously receiving a predetermined number of the AM signals, and measuring the changes in phase of each of the AM signals as the mobile GPS receiver travels, and deriving therefrom an AM position signal. A reference station for receiving the GPS and AM signals provides correction signals via a cellular telephone network which receives and transmits the correction signals to the mobile GPS receiver station.

Abstract: The interference detection and characterization system of this invention supports modern communication systems which have to contend with a variety of intentional and unintentional interference souces. As an add-on to existing communications equipment, the invention employs novel signal processing techniques to automatically detect the presence of communications channel irregularities in near real-time and alert the attending operator. Information provided to the operator through a user-friendly interface is used to characterize the type of interference and its degree of severity. Once characterized, the information is used by the operator to take corrective actions including the activation of alternative communication plans or, in some instances, mitigation of the interference. Since output from the system of this invention lends itself well to expert system and neural network environments, such systems could be employed to further aid the operator.

Abstract: A demodulator apparatus for demodulating a data bearing broadcast signal in the absence of mixers and without incurring quantization errors. The apparatus incorporates a receiver for receiving a broadcast signal and producing therefrom a predetermined intermediate carrier frequency (F.sub.IF), transversal filter connected to receive the intermediate carrier frequency F.sub.IF has N active stages and tap weight means at each of said stages for entering a tap weight sequence to yield maximum correlation energy when desired alignment occurs to thereby make phase and frequency agreement between local timing and the received signal, and the frequency F.sub.IF is sampled at a clock rate (F.sub.s) of: ##EQU1## wherein F.sub.IF is the intermediate frequency and K is a scaling factor which is related to the number of carrier cycles per stage, the transversal filter includes a charge coupled device having the N active stages.