Abstract: A spread-spectrum-phase-locked-loop apparatus and method for coherent detection without a pilot channel. The system comprises symbol-matched means, a voltage-controlled oscillator (VCO), a first product device, a second product device, a third product device, a fourth product device, a first combiner, a second combiner, and a fifth product device. The method comprises the steps of despreading, from a received spread-spectrum signal, an in-phase component and a quadrature-phase component of a symbol sequence signal using the symbol-matched means. The first and second product devices multiply the despread in-phase component by the VCO-cosine and the VCO-sine signals, respectively, to generate a first and a second product signal. The third and fourth product devices multiply the despread quadrature-phase component by the VCO-sine and the VCO-cosine signals, respectively, to generate a third and a fourth product signal.

Abstract: An improvement to a code-division-multiple-access (CDMA) system employing spread-spectrum modulation, with the CDMA system having a base station (BS) and a plurality of remote stations. The base station has a BS-spread-spectrum transmitter and a BS-spread-spectrum receiver. A remote station has an RS-spread-spectrum transmitter and an RS-spread-spectrum receiver. The BS transmitter transmits a broadcast common-synchronization channel, which includes a frame-timing signal. The broadcast common-synchronization channel has a common chip-sequence signal, which is common to the plurality of remote stations. In response to the RS-spread-spectrum receiver receiving the broadcast common-synchronization channel, and determining frame timing from the frame-timing signal, an RS-spread-spectrum transmitter transmits an access-burst signal. The BS-spread-spectrum transmitter, responsive to the BS-spread-spectrum receiver receiving the access-burst signal, transmits an acknowledgment signal.

Abstract: An optical interconnect for use with SIMD processors, including holographic-optical elements, dove prisms, beamsplitters and a processor. Laser diodes, with each operating at a different wavelength, generate coherent-light beams at different wavelengths. A fiber combiner, an optical fiber and a fiber splitter are connected to divide output light from the laser diodes into equal path lengths. The output light is modulated by data from a respective SIMD processor. The output light forms an input ring at an input plane. Each holographic-optical element reflects only one wavelength of the output light. Dove prisms perform certain fixed interconnections. Beamsplitters reflect the light from the selected optical channel to an output-ring array.

Abstract: A two-step automatic-gain-control (AGC) loop for use with a receiver. An AGC amplifier amplifies a received signal. From an output signal from the AGC amplifier, a received-signal-strength-indicator (RSSI) circuit generates an RSSI signal proportional to a received-signal-power level of the received signal. An RSSI-mapping circuit has an RSSI-mapping table. From the RSSI signal, the RSSI-mapping circuit, using the RSSI-mapping table, generates an AGC signal. An AGC-storing circuit stores the AGC signal. The AGC amplifier uses the stored-AGC signal to adjust the AGC gain. A converter circuit converts the output signal from the AGC amplifier to an in-phase component and a quadrature-phase component at a processing frequency. The error circuit determines an error signal from the in-phase component and the quadrature-phase component.

Abstract: An improvement to a code-division-multiple-access (CDMA) system employing spread-spectrum modulation, with the CDMA system having a base station (BS) and a plurality of remote stations. The base station has a BS-spread-spectrum transmitter and a BS-spread-spectrum receiver. A remote station has an RS-spread-spectrum transmitter and an RS-spread-spectrum receiver. The BS transmitter transmits a broadcast common-synchronization channel, which includes a frame-timing signal. The broadcast common-synchronization channel has a common chip-sequence signal, which is common to the plurality of remote stations. In response to the RS-spread-spectrum receiver receiving the broadcast common-synchronization channel, and determining frame timing from the frame-timing signal, an RS-spread-spectrum transmitter transmits an access-burst signal. The BS-spread-spectrum transmitter, responsive to the BS-spread-spectrum receiver receiving the access-burst signal, transmits an acknowledgment signal.

Abstract: A spread-spectrum-phase-locked-loop apparatus and method for coherent detection without a pilot channel. The system comprises symbol-matched means, a voltage-controlled oscillator (VCO), a first product device, a second product device, a third product device, a fourth product device, a first combiner, a second combiner, and a fifth product device. The method comprises the steps of despreading, from a received spread-spectrum signal, an in-phase component and a quadrature-phase component of a symbol sequence signal using the symbol-matched means. The first and second product devices multiply the despread in-phase component by the VCO-cosine and the VCO-sine signals, respectively, to generate a first and a second product signal. The third and fourth product devices multiply the despread quadrature-phase component by the VCO-sine and the VCO-cosine signals, respectively, to generate a third and a fourth product signal.

Abstract: A spread-spectrum receiver for time sharing a correlator for simultaneously receiving a plurality of parallel spread-spectrum signals. A combined multiplicity of symbols includes a multiplicity of symbols, simultaneously occurring during a symbol-time duration, from a plurality of spread-spectrum signals. A demultiplexer demultiplexes a sequence of the combined multiplicity of symbols into a plurality of symbol registers. Each of the symbol registers stores the chip-sequence signals corresponding to the combined multiplicity of symbols which were sent to the particular symbol register. A multiplexer selects a symbol register, other than the symbol register selected by the demultiplexer. The multiplicity of chip-sequence signals stored in the selected symbol register by the multiplexer are compared by a comparator with a multiplicity of replicas of the chip-sequence signals used to generate the spread-spectrum signals.

Abstract: A system and method using a Costas loop to effect accelerated convergence with minimal system complexity. The system comprises an in-phase-limiter and a quadrature-phase limiter, operatively coupled to an EXCLUSIVE-OR gate, for exclusively-ORing an in-phase-sign signal and a quadrature-phase-sign signal to output a first error signal, responsive to the signals having same signs, or a second error signal, responsive to the signals having different signs. An AGC circuit, operatively coupled to an output of the EXCLUSIVE-OR gate, increases and decreases a voltage level of an AGC signal responsive to two consecutive first or second error signals and consecutive dissimilar error signals, respectively. A voltage-controlled oscillator, operatively coupled to an output of the AGC circuit and responsive to the increased or decreased voltage level, changes the frequency of a voltage-controlled-oscillator output signal.

Abstract: A system and method for encoding and transmitting data with a spread-spectrum packet-switched system. Data to be transmitted by a packet transmitter are encoded for privacy and to restrict intelligent receipt of the data to the intended recipient. The encoded data is demultiplexed into sub-data-sequence signals which are spread-spectrum processed and then combined as a multichannel spread-spectrum signal. The multichannel spread-spectrum signal is concatenated with a header to output a packet-spread-spectrum signal which is transmitted over radio waves to a packet receiver. The packet receiver obtains timing for the multichannel spread-spectrum signal from the header. The multichannel spread-spectrum signal is then despread and multiplexed as received-encoded data. The received-encoded data is decoded by the intended recipient and is stored in a receiver memory for output.

Abstract: A multi-clock matched filter for receiving signals with multipath. The signals may be modulated with a spread-spectrum spreading sequence, or other analog or digital signal. A number of signal registers store digital samples of the received signal. The gating of digital samples into each of the signal registers is controlled by a separate clock timing. The timing sequence may be derived from a common clock. A multiplexer sequentially selects each of the signal registers, and passes the respective content of each signal register to a matched filter. A number of delay-locked-loop circuits track each of the multipath signals, and generate the timing sequence for gating signal registers.

Abstract: A system and method for synchronizing a Costas Loop for demodulating a received spread-spectrum signal having data and a first arbitrary phase angle, .phi.(t), using a phase detector, a phase unwrapping subsystem, an oscillator, a derotator and a decision device. A second arbitrary phase angle, .theta.(t), is generated from an in-phase component and a quadrature-phase component of the received spread-spectrum signal. The second arbitrary phase angle, .theta.(t), is proportional to the first arbitrary phase angle, .phi.(t). A value of .theta. proportional to .theta.(t) is then estimated. The estimated .theta. value is processed to obtain an estimate for the .phi.value, and a cosine and a sine of the estimated .phi. value are generated by the oscillator. The derotator derotates the in-phase-component and the quadrature-phase component of the received spread-spectrum signal with the cosine and the sine of the estimated .theta. value to generate a demodulated signal.

Abstract: An optical interconnect for use with SIMD processors, including holographic-optical elements, dove prisms, beamsplitters and a processor. Laser diodes, with each operating at a different wavelength, generate coherent-light beams at different wavelengths. A fiber combiner, an optical fiber and a fiber splitter are connected to divide output light from the laser diodes into equal path lengths. The output light is modulated by data from a respective SIMD processor. The output light forms an input ring at an input plane. Each holographic-optical element reflects only one wavelength of the output light. Dove prisms perform certain fixed interconnections. Beamsplitters reflect the light from the selected optical channel to an output-ring array.

Abstract: A fuzzy-logic spread-spectrum adaptive power control system comprising a base station and a plurality of remote units. The base station receives a spread-spectrum signal, and samples the despread spread-spectrum signal at a peak correlation time of the data channel, and at a non-peak correlation time of the data channel. This in turn generates a signal level and a noise level, respectively. A signal-to-noise ratio calculator generates a signal-to-noise ratio from the signal level and the noise level. A fuzzy-logic controller compares the signal-to-noise ratio to a set of predetermined thresholds, and using a state machine, generates a control signal which is thereby transmitted to the remote unit, indicating the amount by which to increase or decrease transmitted power. Each remote unit demodulates the control signal, and a transmitter controller adjusts a power level of the remote-unit spread-spectrum transmitter.

Abstract: A system and method using a Costas loop to effect accelerated convergence with minimal system complexity. The system comprises an in-phase-limiter and a quadrature-phase limiter, operatively coupled to an EXCLUSIVE-OR gate, for exclusively-ORing an in-phase-sign signal and a quadrature-phase-sign signal to output a first error signal, responsive to the signals having same signs, or a second error signal, responsive to the signals having different signs. An AGC circuit, operatively coupled to an output of the EXCLUSIVE-OR gate, increases and decreases a voltage level of an AGC signal responsive to two consecutive first or second error signals and consecutive dissimilar error signals, respectively. A voltage-controlled oscillator, operatively coupled to an output of the AGC circuit and responsive to the increased or decreased voltage level, changes the frequency of a voltage-controlled-oscillator output signal.

Abstract: A spread-spectrum-matched-filter apparatus including a code generator, an in-phase-symbol-matched filter, a quadrature-phase-symbol-matched filter, an in-phase-frame-matched filter, a quadrature-phase-frame-matched filter, and a controller. The code generator generates replicas of a chip-sequence signal, which are used to set the symbol-impulse responses of the inphase-symbol-matched filter and the quadrature-phase-symbol matched filter. The in-phase-frame-matched filter and the quadrature-phase-frame-matched filter detect a despread-header-symbol-sequence signal and generate a maximum output signal which may be used as a data-start signal or for synchronizing the timing of the controller as to when to trigger sampling of the A/D converter, the output of the symbol-matched filters, detection of the data-symbol-sequence signal and other time-dependent processes.

Abstract: A multistage linear receiver for extracting data embedded in a received spread-spectrum signal having a plurality of channels using a direct sequence code division multiple access system. The multistage receiver comprises an initial plurality of spread-spectrum detectors, a plurality of detector weighting devices, a first plurality of product devices, a first combiner, a first plurality of spread-spectrum detectors, a first plurality of weight-product devices and an output combiner. The initial plurality of spread-spectrum detectors despreads and delays the plurality of channels to generate a plurality of detector-output signals. The detector weighting devices weight the plurality of detector-output signals with a plurality of detector weights as a plurality of weighted-detector signals.

Abstract: A system and method for synchronizing a Costas Loop for demodulating a received spread-spectrum signal using a squaring device, a filter, a phase detector, a phase unwrapping subsystem, an oscillator, a derotator and a decision device. Phase-shift-keying modulation is removed from a received spread-spectrum signal through squaring. An in-phase component and a quadrature-phase component of the received spread-spectrum signal are filtered to generate an arbitrary phase angle, .theta.(t). A value of .theta. proportional to .theta.(t) is then estimated. The estimated .theta. value is processed to obtain an estimate for the .phi. value, and a cosine and a sine of the estimated .phi. value are generated by the oscillator. The derotator derotates the in-phase-component and the quadrature-phase component of the received spread-spectrum signal with the cosine and the sine of the estimated .theta. value to generate a demodulated signal. The decision device evaluates the demodulated signal and outputs data.

Abstract: A fuzzy-logic spread-spectrum adaptive power control system comprising a base station and a plurality of remote units. The base station receives a spread-spectrum signal, and samples the despread spread-spectrum signal at a peak correlation time of the data channel, and at a non-peak correlation time of the data channel. This in turn generates a signal level and a noise level, respectively. A signal-to-noise ratio calculator generates a signal-to-noise ratio from the signal level and the noise level. A fuzzy-logic controller compares the signal-to-noise ratio to a set of predetermined thresholds, and using a state machine, generates a control signal which is thereby transmitted to the remote unit, indicating the amount by which to increase or decrease transmitted power. Each remote unit demodulates the control signal, and a transmitter controller adjusts a power level of the remote-unit spread-spectrum transmitter.

Abstract: An optical interconnect for use with SIMD processors, including holographic-optical elements, dove prisms, beamsplitters and a processor. Laser diodes, with each operating at a different wavelength, generate coherent-light beams at different wavelengths. A fiber combiner, an optical fiber and a fiber splitter are connected to divide output light from the laser diodes into equal path lengths. The output light is modulated by data from a respective SIMD processor. The output light forms an input ring at an input plane. Each holographic-optical element reflects only one wavelength of the output light. Dove prisms perform certain fixed interconnections. Beamsplitters reflect the light from the selected optical channel to an output-ring array.

Abstract: A system and method using a Costas loop to effect accelerated convergence with minimal system complexity. The system comprises an in-phase-limiter and a quadrature-phase limiter, operatively coupled to an EXCLUSIVE-OR gate, for exclusively-ORing an in-phase-sign signal and a quadrature-phase-sign signal to output a first error signal, responsive to the signals having same signs, or a second error signal, responsive to the signals having different signs. An AGC circuit, operatively coupled to an output of the EXCLUSIVE-OR gate, increases and decreases a voltage level of an AGC signal responsive to two consecutive first or second error signals and consecutive dissimilar error signals, respectively. A voltage-controlled oscillator, operatively coupled to an output of the AGC circuit and responsive to the increased or decreased voltage level, changes the frequency of a voltage-controlled-oscillator output signal.