Abstract: A method and apparatus is provided for creating a composite waveform. This composite waveform is created by coding a plurality of input digital information signals. Subsequently, the plurality of coded input digital information signals are communicated over a communication medium to a digital combiner. The digital combiner combines the plurality of coded input digital information signals. Finally, the digitally combined information signal is spectrally shaped to form a composite waveform. These composite waveform creation principals may be applied to digitally encoded voice subbands in a subband coding system as well as channel information in a direct sequence code division multiple access (DS-CDMA) communication system transmitter.

Abstract: A system and method for communicating information signals using spread spectrum communication techniques. PN sequences are constructed that provide orthogonality between the users so that mutual interference will be reduced, allowing higher capacity and better link performance. With orthogonal PN codes, the cross-correlation is zero over a predetermined time interval, resulting in no interference between the orthogonal codes, provided only that the code time frames are time aligned with each other. In an exemplary embodiment, signals are communicated between a cell-site and mobile units using direct sequence spread spectrum communication signals. In the cell-to-mobile link, pilot, sync, paging and voice channels are defined. Information communicated on the cell-to-mobile link channels are, in general, encoded, interleaved, hi-phase shift key (BPSK) modulated with orthogonal covering of each BPSK symbol along with quadrature phase shift key (QPSK) spreading of the covered symbols.

Abstract: A novel PN code acquisition and demodulation circuit comprise an analog receiver coupled to an analog to digital converter. The digital output of the converter is passed through an N chip width parallel correlator. The parallel outputs are coherently accumulated to provide N soft decision data values one of which is indicative of the proper replica code for locking onto the data. All of the soft decision data values are stored in a high speed memory in real time. Subsequently non-coherent accumulated soft decision data is employed to detect the proper PN replica code. Logic selection means accesses the soft decision data stored in the high speed memory in non real time and selects the best estimate for the soft decision data and applies the soft decision data to a demodulator in non-real time to recover the hard data encoded in the received PN coded data.

Abstract: A receiver for pseudorandom noise (PRN) encoded signals consisting of a sampling circuit, multiple carrier and code synchronizing circuits, and multiple digital correlators. The sampling circuit provides digital samples of a received composite signal to each of the several receiver channel circuits. The synchronizing circuits are preferably non-coherent, in the sense that they track any phase shifts in the received signal and adjust the frequency and phase of a locally generated carrier reference signal accordingly, even in the presence of Doppler or ionospheric distortion. The multiple correlators in each channel correlates the digital samples with locally generated PRN codes having multiple offsets, to produce a plurality of correlation signals. The plurality of correlation signals are fed to a parameter estimator, from which the delay and phase parameters of the direct path signal, as well as any multipath signals, may be estimated, and from which a range measurement may be corrected.

Abstract: An improved system and method for communicating information over in-phase (I) and quadrature phase (Q) communication channels in a spread spectrum communication system is disclosed herein. In an exemplary implementation, first and second information signals are respectively transmitted over the I and Q communication channels using direct sequence spread spectrum communication signals. In-phase pseudorandom noise (PN.sub.I) and quadrature phase pseudorandom noise (PN.sub.Q) signals of predetermined PN codes are used for spreading the first and second information signals, respectively. In particular, the PN.sub.I and PN.sub.Q signals are respectively combined with the first and second information signals and an orthogonal function signal to provide I-channel and Q-channel modulation signals. The I-channel and Q-channel modulation signals are used for modulating in-phase (I) and quadrature phase (Q) carrier signals for transmission to a receiver via the I and Q communication channels, respectively.

Abstract: A wireless Local Area Network (LAN), in which each wireless adapter includes a controller and a transceiver which are located a finite distance from each other. Each controller and transceiver has their own hop clock and hop table. A data interface which includes a command set is defined between the controller and the transceiver. The command set includes commands and procedures for synchronizing the hop clocks and hop tables between the controller and the transceiver.

Abstract: A digital radio transceiver uses a differential 4-ary frequency shift keying (D4FSK) modulation scheme to achieve a radio that is low cost, miniaturizable, low in power consumption, and high in spectral efficiency. An adaptive digital "slicer" looks at a digitized FM video signal produced in the receiver to determine if the data sent is a 00, 01, 10 or 11. The digitized FM video signal is first processed by a differential decoder, the output of which is input to a peak detector. The peak detector outputs a signal upon the occurrence of a three-step transition, i.e., a peak-to-peak voltage value. Two-step and three-step transitions are separately detected and used to perform digital clock recovery. A carrier detect circuit uses a digital bit filter to produce a carrier detect signal that is reliable and glitch-free. The digital radio transceiver uses frequency hopping spread spectrum transmission.

Abstract: A multiple access communications system reuses a set of N carrier frequencies in adjacent communications sites to provide more than N minimally cross-correlated frequency-hopping communications channels. A first set of communications channels is associated with a first of the communications sites. No two of the channels in the first set employ the same frequency at the same time. A second set of communications channels is associated with a second of the adjacent communications sites. No two of the channels in the second set of channels employ the same one of the N carrier frequencies at the same time. One or more sets of the minimally cross-correlated channels are further defined so that none of the channels in such sets employ the same frequency at the same time as more than a predetermined number of the channels in another of the sets of the minimally cross-correlated frequency-hopping communications channels.

Abstract: A plurality of input signals are processed (75) using a Hadamard transform (52) to produce a combined Walsh covered parallel sequence which is sampled in time. The time samples are commutated (76) by a switch (53) or multiplexer to form a Walsh covered serial sequence. The Walsh covered serial sequence is then quadrature phase shift keyed (77) and transmitted (79).

Abstract: A system for transmitting and receiving outbound and inbound data signals through a satellite communications network, the system having a network data rate and including a satellite and an end user transceiver, the system comprising a half-duplex mobile transceiver for transmitting and receiving the inbound and outbound data signals, respectively, for spreading the inbound data signal from the network data rate to a reduced data rate having an increased signal-to-noise ratio using a spread sequence, and for despreading the outbound data signal from the reduced data rate to the network data rate.

Abstract: A communication system for simultaneously transmitting data and audio signals via a conventional audio communications channel using perceptual coding techniques is disclosed. In a preferred embodiment, a first artificial neural network (NN) at an encoder monitors an audio channel to detect "opportunities" to insert the data signal such that the inserted signals are masked by the audio signal, as defined by the "perceptual entropy envelope" of the audio signal. Under the control of the first NN a data signal containing, for example, an ID or serial number, is encoded as one or more whitened direct sequence spread spectrum signals and/or a narrowband FSK data signal and transmitted at the time, frequency and level determined by the first NN such that the data signal is masked by the audio signal. The audio signal is combined with the spread spectrum and/or the FSK data signal(s) to form a composite signal, which is transmitted to one or more receiving locations via the audio channel.

Abstract: A receiving device for receiving spread spectrum-modulated GPS signal transmitted from GPS (Global Positioning System) satellites to the earth. Received GPS signals are converted into IF signals which are despread-demodulated on the basis of C/A codes, resulting in demodulated PSK signals. Carriers are reproduced from the IF signals and a clock signal for C/A code generator is produced from the reproduced carrier and a local oscillation signal. The PSK signal is demodulated on the basis of a reference frequency of a PLL circuit to obtain a navigation message.

Abstract: An apparatus for decoding a received spread spectrum signal having a data signal modulated with a pseudo-noise code and transmitted as an RF spread spectrum signal. A reference-sequence-storage device holds a reference-pseudo-noise signal, and a receive-sequence storage device holds a received spread spectrum signal. A chip comparator adds each chip of the received spread spectrum signal by each respective chip of the pseudo-noise signal, thereby generating a plurality of chip comparison signals. A summer adds the plurality of chip comparison signals, generating a correlation signal. The comparator compares the correlation signal to a statistically predetermined threshold level, and generates a first data-symbol signal.

Abstract: A demodulator for code-division multiple-access spread-spectrum communications stores received chip data in a separate memory area for each transmitting station. Each area has a capacity of at least two symbols. When a complete symbol is received from a transmitting station, all chip data stored in the corresponding memory area are correlated with the corresponding spreading code, and estimated symbol values are derived from the correlated values. The correlated or estimated value of the oldest symbol is output as a demodulated value. The difference between each estimated symbol value and the previous estimate for the same symbol is multiplied by the spreading code to generate remaining interference values, which are subtracted from all chip data stored in memory areas for other transmitting stations, thereby updating those data.

Abstract: A data demodulator of a receiving apparatus for spread spectrum communication for removing the phase difference remaining after detection for improving reception quality. In-phase and quadrature axis received signals are multiplied by pseudonoise codes PNI(t) and PNQ(t) and the results are averaged by averaging sections for calculating the correlation. By performing correlation processing, .rho.kO cos .theta., -.rho.O sin .theta., .rho.kO sin .theta., and .rho.kO cos .theta. are output when the amplitude of receive path signal is assumed to be .rho., the phase difference to be .theta., and a proportional constant to be kO. These signals are multiplied by in-phase and quadrature axis received signals and the results are added by adders, thereby removing the effect of the phase difference .theta.. The signal is used for data demodulation and data recovery circuit.

Abstract: The power control process of the present invention enables a mobile radiotelephone to continuously update the base station on the power output required. The base station sends a frame to the mobile at a particular rate. If the mobile received and decoded the frame correctly, it sets a power control bit in the next frame to be transmitted to the base station. Based on the error rate of the received power control bits, the base station determines whether to increase or decrease the transmit power.

Abstract: A cellular communication system hops both signalling channels and traffics channels in a common hopping sequence. To obtain system information from the frequency hopping signalling channel, a subscriber unit waits on a predetermined frequency, or carrier, until the frequency hopped signalling channel arrives at the predetermined frequency. Once arrived, the subscriber unit obtains synchronization information, and information related to the hopping sequence, from the signalling channel during the hop. The subscriber unit may then hop in tandem with the system, obtaining further system information in subsequent hops. The cellular communication system supports mobile assisted handoff (MAHO) by allowing a subscriber unit to measure signalling channel of neighboring cells in a similar manner, and using the measurements to assist in communication handoff from a source cell to a neighboring cell.

Abstract: A munitions cartridge transmitter capable of emitting an electromagnetic signal after discharge from a cartridge propelling device comprises a signal generator, an electromagnetic signal transmitter coupled to the generator, an antenna coupled to the transmitter, and a hollow cartridge for housing the generator, the transmitter, and the antenna. The transmitter is energized after discharge of the cartridge propelling device by a power source contained in the cartridge.

Abstract: Methods and apparatus are described for uniquely encrypting a plurality services at a transmission site and for decrypting selected services at a reception site while reducing the amount of encryption related information that must be transmitted to the reception site for decryption purposes. A unique spreading function is generated at the transmission site for each service to be transmitted. A random quantity is then transmitted, and the random quantity is convolved with each spreading function to produce a unique encryption seed for each service. At least a portion of each service is then encrypted using the unique encryption seeds produced for each service. Only the random quantity is transmitted to the reception site along with the encrypted portions of each service. None of the unique encryption seeds are transmitted. At the reception site, the unique spreading functions generated at the transmission site for each service are regenerated.

Abstract: A radio environment measuring system for measuring a propagation state of radio waves includes: a fixed radio apparatus provided in a base station; a mobile radio apparatus operatively connected to the fixed radio apparatus through the radio waves; the mobile radio apparatus having a repeater unit for receiving a transmission signal from the fixed radio apparatus and sending a returned signal to the fixed radio apparatus; and the fixed radio apparatus having a transmission/reception unit for sending the transmission signal to the mobile radio apparatus and receiving the returned signal from the mobile radio apparatus, and a measuring unit for measuring the propagation state of the radio waves, for example, a propagation distance, direction and reception intensity of the radio waves between the fixed radio apparatus and the mobile radio apparatus based on the transmission signal and the returned signal.

Abstract: A method and apparatus for the identification and verification of audio transmission segments, such as may be broadcast by a radio station, consists of the generation of a data stream corresponding in duration to the length of the program segment and including both cumulative time data and segment identification data. The data stream is combined with the program segment to which it relates in a manner in which the data is inaudible on conventional reception apparatus and which does not significantly degrade the audio quality of the program segment. A reception facility is provided to extract the data stream from the recorded audio and compare the data therein with reference data for the transmission, including intended length and time of the segment. By such a comparison verification of the broadcast can be accomplished.

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: The present invention is directed to novel implementation techniques which makes orthogonal CDMA practical in an a short range mobile telephone environment where significant multipath fading exists. Specifically, novel techniques for establishing the time base, frequency, and power control necessary to achieve orthogonality. Use of a high power sounding burst on the outbound link permits: 1) antenna diversity selection to minimize the probability of a faded condition, 2) local frequency locking at the subscriber terminal which avoids the requirement for a costly precision frequency standard, and 3) essentially instantaneous inbound power control based on the outbound receive signal level. This is effective since time division duplexing is used and both transmission and reception take place on the same frequency. With the short frame structure and unique placement of the sounding burst the correlation between the outbound and inbound path losses is very high.

Abstract: A signal acquisition method for a GPS receiver which eliminates the necessity of a clock circuit for keeping the current time and also a backup battery for memory is disclosed. According to the signal acquisition method, upon starting of acquisition of a GPS satellite after the power source to the GPS receiver is turned on, using a matched filter, an acquisition operation is performed for objects of all of GPS satellites which may possibly be disposed until after a signal of at least one of the GPS satellites is acquired.

Abstract: A system for measuring a multipath radio channel impulse response by cross-correlating digital samples of a received pseudo-random signal with a digital copy of the transmitted signal. A transmitter within the system repeatedly transmits the pseudo-random signal across a multipath radio channel. A receiver within the system receives the transmitted signal, as well as delayed versions of the original signal, and digitally samples the received signals. A computer then cross-correlates the samples of the received signal with the digital stored version of the transmitted signal to produce a measure of the impulse response of the multipath radio channel.

Abstract: A spatial combiner for connection to a receiver used in conjunction with a lurality of direction-sensitive antennas for receiving a spread-spectrum communication signal in the presence of interference includes a steering network, a plurality of normalizers, and a plurality of combiners. The steering network combines N inputs from N antennas and produces outputs J.sub.1, J.sub.2, . . . , J.sub.M, with M being a multiple of K and K a positive integer such that each M output is a weighted sum of N inputs from the antennas. The normalizers receive and normalize the M outputs to unit energy and produce normalized outputs J .sub.1, J .sub.2, . . . , J .sub.M. The combiners receive normalized outputs and sum the first K outputs to produce output C.sub.1, sum the next K outputs to produce output C.sub.2, and continuing summing outputs in the same manner until summing the last K outputs occurs to produce output C.sub.M/K. The outputs C.sub.1 through C.sub.

Abstract: A direct sequence digital spread spectrum receiver acquires and maintains synchronization in a reliable, yet simple manner, even under severe multipath and interference conditions. A sliding correlator and a voltage controlled crystal oscillator (VCXO) cooperate to acquire initial synchronization, and once synchronization is acquired, the VCXO is linearly frequency modulated (FM) for accurate tracking. The difficult problem of keeping the receiver code clock synchronized to that of the transmitter under severe multipath and interference conditions is solved by virtue of a dual switched bandwidth low pass filter section of the tracking circuit, allowing a wide bandwidth for initial acquisition and tracking but once the clocks are aligned, a narrow loop takes over that follows the transmitter closely. A commercially available intermediate frequency (IF) integrated circuit (IC) is used as an amplitude modulated (AM) detector to achieve the large dynamic range required.

Abstract: One or more interrogating commander stations and an unknown plurality of responding responder stations coordinate use of a common communication medium. Each commander station and each responder station is equipped to broadcast messages and to check for error in received messages. When more than one station attempts to broadcast simultaneously, an erroneous message is received and communication is interrupted. To establish uninterrupted communication, a commander station broadcasts a command causing each responder station of a potentially large first number of responder stations to each select a random number from a known range and retain it as its arbitration number. After receipt of such a command, each addressed responder station transmits a response message containing its arbitration number. Zero, one, or several responses may occur simultaneously.

Abstract: In a first direct-sequence spread spectrum communication system having a transmission circuit where a data signal to be transmitted is coded by a first chip code signal and a receiving circuit for decoding the transmitted data signal with a second chip code signal, the synchronization between the said first and second chip code signals is performed when an asynchronous condition of said first and second chip code signals is detected over a predetermined interval. In a second direct-sequence spread spectrum communication system having a transmission circuit where a data signal having a variable data rate V to be transmitted is coded by a first chip signal having a data rate C and coded by a reference code signal having a data rate R, C>V, R>V. A receiving circuit receives the data signal from the above-mentioned transmission circuit decoded by a second chip signal and a second reference code signal.

Abstract: Identification and extraction of hybrid, frequency-hopped direct sequence pseudo noise (FH/DS), signals from a multiband signal environment is effected by a sequential signal processing technique which examines the distribution of the energy content within a prescribed sub-spectrum window that is iteratively scanned or `slides` across the overall signal spectrum of interest. Based upon this energy content distribution, in particular the extent to which a sub-spectrum window contains energy that exhibits significant conjugate phase symmetry associated with a direct spread signal, the inventive signal processing technique proceeds to emphasize the spectral composition of components of which hybrid signals are comprised and to deemphasize the spectral composition of signals other than those contained in hybrid signals. Potential hybrid signal candidates whose spectral composition has been emphasized are then selectively combined with the deemphasized signals to isolate and identify the hybrid signals.

Abstract: A spread-spectrum code division multiple access interference canceler for reducing interference in a direct sequence CDMA receiver having N chip-code channels. The interference canceler includes a plurality of correlators or matched filters, a plurality of spread-spectrum-processing circuits, subtracting circuits, and channel correlators or channel-matched filters. Using a plurality of chip-code signals, the plurality of correlators despreads the spread-spectrum CDMA signal as a plurality of despread signals, respectively. The plurality of spread-spectrum-processing circuits uses a timed version of the plurality of chip-code signals, for spread-spectrum processing the plurality of despread signals, respectively, with a chip-code-signal corresponding to a respective despread signal. For recovering a code channel using an i.sup.

Abstract: A direct sequence code-division multiple access (DS CDMA) communication system schedules conveyance of blocks (400) of information such that the blocks arrive at a base-site (130) just-in-time for transmission during a discrete frame (301-305) of an air-interface. The DS CDMA communication system implements both circuit switching and packet switching approaches to provide trunking efficiencies while balancing between system loading constraints and time delay of blocks (400) during conveyance.

Abstract: A time domain communications system wherein a broadband of time-spaced signals, essentially monocycle-like signals, are derived from applying stepped-in-amplitude signals to a broadband antenna, in this case, a reverse bicone antenna. When received, the thus transmitted signals are multiplied by a D.C. replica of each transmitted signal, and thereafter, they are, successively, short time and long time integrated to achieve detection.

Abstract: An HF radio transceiving apparatus that maintains communication integrity by employing a plurality of receivers, each capable of operating in separate and independent communication modes. One embodiment of the apparatus includes an antenna, a programmed controller having a plurality of control signals, first and second receivers and a transmitter section. The receivers receive and demodulate radio signals transmitted from external radios in common or mutually exclusive communication modes, and provide link-data information to the programmed controller. The transmitter, responsive to the programmed controller and coupled to the antenna, transmits modulated data in one of the common or mutually exclusive communication modes.

Abstract: A spread spectrum receiver for use in spread spectrum communication systems is disclosed. The spread spectrum receiver of the present invention includes an analog-to-digital converter for receiving an analog spread spectrum signal, and for converting the received analog signal to a digital signal. The spread spectrum receiver also includes a digital frequency offset correction device, for modifying the digital signal in accordance with a frequency correction term signal to thereby correct for frequency offset in the received analog signal. The spread spectrum receiver also contains a Rake receiver. The spread spectrum receiver searches through the modified digital signal to identify M of the main and multipath return signals having the strongest signal strengths.

Abstract: Spread spectrum communication using direct sequences that approximate a swept frequency waveform in which successive square waves are formed by the chips making up the sequence, and in which the durations of the square waves extend over a plurality of chips, and in which the frequency of the square waves varies across at least a portion of the sequence. Information is encoded by varying the direction of the direct sequence, so that the sequence is transmitted as either a forward or a reverse frequency-swept sequence. The spectrum of the direct sequences is in a passband. The direct sequence biphase modulates a carrier (e.g., RF) to produce a spread-spectrum signal with two passbands centered about the frequency of the modulated carrier.

Abstract: A transceiver for transmitting and receiving digital data is disclosed. The transceiver employs direct sequence spread spectrum communications techniques for reducing interference among multiple users in a communications network environment. Each transceiver has a transmitter for locking a digital bit stream to a predetermined spread spectrum chip sequence and carrier signal. Frequency of the carrier signal and the chip sequence. Both the carrier signal, the chip sequence and the bit stream rate are derived from an integrally related to an accurate reference frequency to facilitate rapid acquisition and decoding of the signal by another transceiver. To provide for multiple communications channels on a single transmission medium, means for producing selectable carrier frequencies and/or selectable spreading sequences are included.

Abstract: A method and apparatus for combining multipath spread-spectrum signals are provided. The multipath combining is accomplished by detecting an envelope of an input differential phase shift keyed signal communicated over a communication channel. Subsequently, a replica of a multipath echo structure for the communication channel is detected within the detected envelope. In addition, a multipath echo structure weighted differential phase shift keyed signal with the detected replica of the multipath echo structure for the communication channel. Finally, the multipath echo structure weighted differential phase shift keyed signal is integrated over a one symbol period centered on a correlation peak such that power from a plurality of signal paths determines an output data bit.

Abstract: A method for increasing the bit rate of a data link is to select two additional 31-bit chip code patterns that are orthogonal to the present two chip codes, and to each other. This method will not require any more bandwidth that the present 10 MHz used. This method suggests that each of the four chip code patterns are assigned a two bit value i.e.: 00, 01, 10, 11. At present, the two correlated chip codes represent data in a pulse position method. No information is transferred by determining which of the two chip codes actually correlated. This new method suggests each of the four chip code patterns will still perform the pulse position modulation and also provide two additional bits of data. These additional two bits of data will up the data rate of the link by 100 percent. Alternatively, the data rate may be increased by coding the datasuch that a reduction in duty cycle is realized as well as an increase in the data rate.

Abstract: A communication method in an adaptive CDMA communication system (100) capable of communicating a direct sequence spread spectrum communication signals which comprise bit sequences coded with spreading chip sequences. The method includes the steps of transmitting a DS-SS communication signal (30) having a training bit sequence (31) coded with spreading chip sequence. The method includes the step of despreading the DS-SS communication signal based on the training bit sequence (31) during a training interval. The DS-SS communication signals is despread by adaptively determining a despreading chip sequence. Then, following the training interval determining chip timing offset during a chip timing interval. Finally, bit timing offset is determined during a bit timing interval following the chip timing interval.

Abstract: A signal despreader for use in a CDMA system processes samples of the received signal with filtered replicas of the code coefficient sequences associated with the system users. The symbols transmitted by each system user are recovered using a filtered replica of that user's associated code coefficient sequence. In the disclosed embodiment, the communications channel between each system user's transmitter and the base station is bandlimited. Accordingly, within each user's transmitter, filtering apparatus having a frequency characteristic is utilized to limit the frequency spectrum of each coded signal to a predetermined bandwidth equal to or less than that of the communications channel. Each filtered replica, pursuant to the present invention, reflects this frequency characteristic. In addition, the communications channel also has a frequency characteristic, and each filtered replica can reflect this characteristic as well.

Abstract: Individual information signals encoded with a common block error-correction code are assigned a unique scrambling mask, or signature sequence, taken from a set of scrambling masks having selected correlation properties. The set of scrambling masks is selected such that the correlation between the modulo-2 sum of two masks with any codeword in the block code is a constant magnitude, independent of the mask set and the individual masks being compared. In one embodiment, when any two masks are summed using modulo-2 arithmetic, the Walsh transformation of that sum results in a maximally flat Walsh spectrum. For cellular radio telephone systems using subtractive CDMA demodulation techniques, a two-tier ciphering system ensures security at the cellular system level by using a pseudorandomly generated code key to select one of the scrambling masks common to all of the mobile stations in a particular cell.

Abstract: A portable cellular telephone system including a stationary transceiver for radio communication with a plurality of mobile transceivers within a geographic cell, a mobile transceiver within said geographic cell and having sufficient power to communicate with said stationary transceiver, and a portable transceiver of limited size for personal transport and use. The portable transceiver communicates with the mobile transceiver by spread spectrum techniques, and the mobile transceiver communicates with the stationary transceiver by frequency modulated radio transmission or by digital radio transmission.

Abstract: A spread spectrum CDMA communications system for communicating data and/or digitized voice between a plurality of users to a plurality of PCN units. The spread spectrum communications system is located within a same geographical region as occupied by an existing FDMA, proposed TDMA or any other mobile cellular system. The spread spectrum CDMA communications system includes a plurality of PCN-base stations and a plurality of PCN units. A PCN-base station has a comb filter for notch filtering predetermined channels of the mobile cellular system, a device for converting the format of the data into a form suitable for communicating over radio waves, a spread spectrum modulator for spread spectrum processing the data, and transmitter for transmitting the spread spectrum processed converted data from the PCN-base station to a PCN unit. The PCN-base station also has an antenna, and spread spectrum detectors for recovering data communicated from the PCN units.

Abstract: Circuit for recovery of a plurality of multipath direct sequence spread spectrum signal components received over a time span, wherein the multipath signal components are components of a signal generated from digital data comprised of data bits at a data bit rate modulated by a pseudo-noise code, consisting of a sequence of chips having a chip rate greater than the data bit rate, wherein the sequence of chips is a code repetition period equal or greater than the received time span of the multipath signal components. A plurality of correlators is provided. Each correlator has a first input for coupling to the multipath signal components, a second input, and an output. A pseudo-noise code generator generates a duplicate of the pseudo-noise code. A time delayer is coupled between the second inputs of a mulitiplicity of the correlators and the pseudo-noise code generator for delaying the duplicate of the pseudo-noise code by a multiple of a time delay equal to the time of a chip duration or less.

Abstract: The invention includes the concepts of early-prompt delay tracking, multipath correction of early-prompt delay tracking from correlation shape and carrier phase multipath correction. In early-prompt delay tracking, since multipath is always delayed with respect to the direct signals, the system derives phase and pseudorange observables from earlier correlation lags. In multipath correction of early-prompt delay tracking from correlation shape, the system looks for relative variations of amplitude across the code correlation function that do not match the predicted multipath-free code cross-correlation shape. The system then uses deviations from the multipath-free shape to infer the magnitude of multipath, and to generate corrections pseudorange observables. In carrier phase multipath correction, the system looks for variations of phase among plural early and prompt lags.

Abstract: An ultra-wideband (UWB) receiver utilizes a strobed input line with a sampler connected to an amplifier. In a differential configuration, .+-.UWB inputs are connected to separate antennas or to two halves of a dipole antenna. The two input lines include samplers which are commonly strobed by a gating pulse with a very low duty cycle. In a single ended configuration, only a single strobed input line and sampler is utilized. The samplers integrate, or average, up to 10,000 pulses to achieve high sensitivity and good rejection of uncorrelated signals.

Abstract: Circuitry and concomitant methodology for demodulating Direct-Sequence, Spread-Spectrum Code-Division Multiple-Access (DS/SS CDMA) channel signal using multiple samples per transmitted symbol and a minimum mean squared error criterion to suppress interference. In one embodiment, a bank of cyclically shifted filters determined with reference to the conventional matched filter for CDMA is used to demodulate the channel signal. In another embodiment, a bank of sub-filters determined with reference to the conventional matched filter for CDMA is employed to demodulate the channel signal. In yet another embodiment, the output of a conventional matched filter is oversampled to demodulate the channel signal. Each embodiment utilizes a set of adaptive coefficients selected to minimize the mean square error between the transmitted symbol and detected symbol.

Abstract: A personal assistance system and method for use with a cellular communication system operating over a cellular communication band and having a plurality of cell-sites. A transceiver transmits to the cell-sites a spread spectrum burst of pulses including a service request codeword indicating a request for service from a service provider. A proxy cell-phone, coupled to a preferred one of the cell-sites, originates a cellular call on the cellular communication system to a destination number of the service provider and on behalf of the transceiver to thereby create a cellular communication link between the transceiver and the service provider. A transceiver location feature provides the service provider with the geographic location of the transceiver.

Abstract: In a spread spectrum communication system, sequence signals are developed in both a transmitter and receiver, in each case being derived from a clock signal through digital count-down and logic circuitry including a programmable counter which receives control number defining groups of signals from a memory under control of an indexing counter. A sequence signal in the transmitter is applied through a filter to produce a filtered signal which is propagated as a sequence of variations of alternating polarity with predetermined varying durations occurring in a predetermined distinctive order. A received signal and sequence signal of the same form as in the transmitter are applied to a product detector the output of which is applied to an integrator. Loop circuitry is provided for synchronizing the generation of the sequence signal in the receiver with that in the transmitter. A plurality of channels may be provided, using common synchronizing and other circuitry.