Abstract: A method for receiving and processing data in a portable transceiver (20) comprises the steps of receiving (320) at least one information signal and decoding (325) the at least one information signal to recover information included therein. The method further comprises the steps of generating (345) a pseudo-noise (PN) sequence in accordance with the information.

Abstract: Method of demodulating a signal including a plurality of time-dispersed signal components such as resulting from receiving in a multipath environment. A plurality of correlators are provided. The period of expected time uncertainty is scanned to identify the highest energy signal components. Each correlator is assigned to process one of the highest energy signal components. Each of the correlator outputs is pase corrected to compensate for carrier phase differences. The correlator outputs are coherently combined to provide a data output.

Abstract: A method and apparatus for masking the presence and content of data transmissions includes a mobile transmitter which encodes the data by means of a pseudorandom spreading (PRS) code having a chip rate, and which transmits it at a carrier frequency. A masking transmitter remote from the mobile transmitter encodes a carrier at the same frequency with a second PRS sequence having the same chip rate, and transmits it at a power level higher than the power level of the mobile transmitter. A signal interceptor cannot separate the mobile and masking station carriers on a frequency basis. The relatively low-power mobile station PRS signal is difficult to detect in the presence of the high-power masking station code. The intended receiver (master station) receives an ensemble signal which is principally masking station signal. The master station regenerates the known masking station PRS code and subtracts it from the ensemble signal to leave a residue signal which contains the data-bearing mobile station PRS signal.

Abstract: Apparatus and a method for transmitting a direct sequence, spread spectrum communication system signal. A transmitter (10) that receives a variable data rate information bearing input signal from a digital data source (12) includes a forward error correction encoder (80) that provides redundancy and an interleaver (82) that rearranges the input data. The forward error correction encoder and interleaver minimize the effect of errors that arise in the propagation of the transmitted signal. The output of the interleaver is applied to the input of a Hadamard encoder (84), which converts data words from the interleaver into one of N orthogonal codes, producing a Hadamard signal that varies at a bit rate that changes as the data rate of the information bearing signal varies. A pseudorandom number code generator (16) produces a code signal comprising a pseudorandom sequence of chips supplied at a constant chip rate.

Abstract: An improved mobile telephone system, including a process and apparatus for detecting fraudulent requests for roamer cellular telephone services before the requested service is granted. The improvement comprises a distributed, readily updatable fraud prevention processor which facilitates a plurality of independent, geographically dispersed cooperating cellular networks to each locally determine if a roamer request for service is from a valid, currently authorized user subscriber before cellular telephone service is provided by the visited cellular network.

Abstract: A code division multiple access (CDMA) communication system (10) for reuse of available spreading codes includes a first communication device (100) and a second communication device (106). The first and second communication devices (100, 106) are capable of identifying spreading codes and operating frequencies that are optimum for their respective radios. The identity of the optimum spreading code and the frequency of the optimum frequency is communicated from one communication device (100) to another (106), hence allowing the two devices to communicate with each other using their respective optimum codes and frequencies. These codes and frequencies may be periodically updated to provide reusability of codes. By dynamically updating codes and frequencies without the use of a central station, the efficiency and reusability of codes in the CDMA system (10) is significantly enhanced.

Abstract: Method of processing a direct sequence spread spectrum communication system signal wherein digital data comprised of data bits is modulated by a first pseudo-noise code comprised of a sequence of chips, the pseudo-noise chip rate greater than said date bit rate, each chip having a chip period, said sequence repeating at a code period, and the pseudo-noise modulated data modualates a carrier frequency resulting in the signal. Digital samples are made of the signal. A second pseudo-noise code replicates the first pseudo-noise code. A first correlation is made of the sampled signal and the second pseudo-noise code. A second correlation is made of the sampled signal and the second pseudo-noise code delayed by one chip period. A first correlated signal energy value represents the signal energy of the first correlation. A second correlated signal energy value represents the signal energy of the second correlation.

Abstract: A correlator for processing a direct sequence spread spectrum communication system signal, wherein digital data comprised of data bits at a data bit rate is modulated by a first pseudo-noise code comprised of a sequence of chips having a pseudo-noise chip rate greater than the data bit rate, each chip having a chip period, the sequence repeating at a code period, and the pseudo-noise modulated data modulates a carrier resulting in the signal. A sampler produces digital samples of the signal. A pseudo-noise code generator produces a second pseudo-noise code replicating the first pseudo-noise code. Circuity time syncronizes the second pseudo-noise code to maximize a combined value of correlated signal energy, thereby time locking the first pseudo-noise code and the second pseudo-noise code.

Abstract: Method for indicating the end of an acquisition procedure between a transmitter and receiver in a direct sequence spread spectrum communications system. At a transmitter, a first acquisition code having a first acquisition code period and comprised of digital bits at a first bit rate is generated. The first digital acquisition code is modulated by a pseudo-noise code repeating at a pseudo-noise code period and consisting of a sequence of chips at a chip rate greater than the first bit rate, and wherein the first acquisition code period is an integer multiple of the pseudo-noise code period. A carrier frequency is modulated by the first digital acquisition code modulated by the pseudo-noise code. The carrier is modulated by the first digital acquisition code modulated by the pseudo-noise code is transmitted for a first period of time.

Abstract: Apparatus for indicating the end of an acquisition procedure between a transmitter and receiver in a direct sequence spread spectrum communications system. A transmitter generates a first acquisition code having a first acquisition code period and comprised of digital bits at a first bit rate. A circuit modulates the first digital acquisition code by a pseudo-noise code repeating at a pseudo-noise code period and consisting of a sequence of chips at a chip rate greater than the first bit rate. The first acquisition code period is an integer multiple of the pseudo-noise code period. A circuit modulates a carrier by the first digital acquisition code modulated by the pseudo-noise code. The carrier modulated by said first digital acquisition code modulated by said pseudo-noise code is transmitted for a first period of time. A circuit synchronizes a receiver to the chip rate and carrier frequency. A circuit synchronizes the receiver to the pseudo-noise code period.

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 spread spectrum communication system having a plurality of transmitters at remote locations capable of transmitting information to one or more receivers during a plurality of information time durations. A message structure interposing the plurality of information time durations with a plurality of preamble time durations, during which time the receiver detects message transmission, is also provided.

Abstract: A receiver of a direct sequence spread spectrum system includes a period counter for counting a period of a system clock, and outputting a data demodulation signal approximately every half-PN period, a peak detector for detecting a peak in the output from an adder until reaching a data demodulation point for every data demodulating period, and outputting the value of the peak to the period counting means, a peak position detector for recognizing the detection of the peak in the peak detecting means, storing a current position of the peak from the period counting means, and then providing the peak position at a data demodulation point after the ending of one period, a timing recovery circuit for receiving position information about the current peak position from the peak position detecting means when beginning every data demodulation operation, and controlling the period counting means to move the peak position to allow the peak position of the following period to be observed in a desired position, and demodul

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, bi-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: An apparatus for transmitting and receiving packets of data among a multitude of base and remote units utilizing a frequency hopping technique. The apparatus uses a single clock source for synchronizing the analog signal processing circuit, the modular encoder and the micrprocessor, and uses an inexpensive microprocessor with a serial peripheral interface.

Abstract: A frequency-hopping cordless telephone system is described which adds digitized audio to a pseudorandom frequency hopping pattern for voice encryption. The randomly selected start point of a very long pseudoramic pattern generator is transferred to the handset by way of an infrared path at each off-hook. In addition, the infrared path is used to synchronize the clocks of the handset and the associated base module when the cordless telephone is in an on-hook position.

Abstract: A radio transceiver system is provided with transceivers for transmitting an outbound signal at least at one transmitting frequency and for receiving an inbound signal at least at one receiving frequency. Baseband signal processors are also provided for baseband processing of the outbound signal before conversion up to the transmitting frequency and of the received inbound signal after conversion down from the receiving frequency. To reduce cable laying in equipment racks and to simplify the realization of baseband frequency hopping, a bidirectional serial digital transmission channel is provided between transceivers and baseband signal processors, whereby both the inbound signal from a transceiver and the outbound signal applied to the transceiver are time-division multiplexed to said bidirectional serial digital transmission channel.

Abstract: The invention discloses a method of measuring the rough frequency deviation in digital communication transmissions with echo propagation, particularly in the short-wave domain. A repeatedly transmitted PN sequence serves as the preamble of a data block. This PN sequence is compressed at the receiving end in matched filters provided in each one of a plurality of simultaneous, frequency offset Doppler channels. The Doppler channel having the greatest amplitude in the quadrature signal is selected for a determination of the rough frequency deviation. To detect a pattern in the preamble, the quadrature signals are examined for similarities by an amplitude comparison or in a cross-correlation process.

Abstract: A spread-spectrum communication apparatus has code generators for generating spread-spectrum and reverse spread-spectrum codes. Rather than using a code generator which differs for every apparatus, the code generators have an identical construction for every apparatus. Specifically, each apparatus is provided with a programmable ROM storing a value specific to each apparatus. When power is introduced to the apparatus, the value specific to the apparatus is read out of the programmable ROM first. Each apparatus generates a code, which is specific to the apparatus, used in spreading and reverse-spreading in dependence upon the specific value that has been read out of the ROM.

Abstract: A multi-frequency electronic signal transmitter includes apparatus for transmitting an electronic signal on each of a plurality of transmission frequencies in succession such that the signal is detectable substantially without interruption by a compatible receiver within range of the signal, which is tuned to any one of the transmission frequencies. Direct digital synthesis circuitry is responsive to digital data representing the amplitude of respective discrete portions of a sinusoidal waveform for generating an analog signal corresponding thereto. Frequency control circuitry is provided for controlling the direct digital synthesis circuitry to generate the analog signal on each of the selected frequencies in succession. In one embodiment, the transmission frequencies correspond to selected frequencies in an amplitude modulated (AM) radio broadcast band. In another embodiment, the transmission frequencies correspond to selected frequencies in a frequency modulated (FM) radio broadcast band.

Abstract: A spread spectrum communications system includes: a transmitter having an input information a modulator for generating a spread spectrum signal in accordance with an input information signal together with a pseudonoise clock signal used to generate a first pseudonoise signal formed of a plurality of chips, a switch for switching on and off a locally generated carrier signal of said input information signal in accordance with the spread spectrum signal, a first means for inverting a phase of the spread spectrum signal when the value of the pseudonoise signal is equal to one, a second means for multiplying the inverted-phase spread spectrum signal by the carrier signal so as to produce a transmit signal at an output of the second means, and an output means for outputting the transmit signal from the second means so that the transmit signal is transmitted from the transmitter; and a receiver which receives the transmit signal from the transmitter, the receiver having a detector for obtaining a baseband signal fr

Abstract: Method for carrier frequency correction in a direct sequence code division multiple access communication system having a carrier frequency, consisting of an expected carrier frequency and a carrier frequency error, modulated by a pseudo-noise code. A local frequency is produced equal to the expected carrier frequency. Received signals are demodulated of the pseudo-noise and mixed with the local frequency. The demodulated signals consist of in-phase signal components and quadrature signal components and the carrier frequency error. Each of the demodulated signal are converted to digital samples. Each signal digital sample is multiplied by stored digitized samples of a plurality of sinusoidal tones to produce a product corresponding to each tone. Each product corresponding to each tone is squared. The resulting squared products are compared to determine which squared product has the maximum value.

Abstract: A high PN code rate receiving system is provided for receiving, recovering and tracking a high rate PN composite code comprising a low rate PN code combined with a high rate PN code and wherein the receiving system comprises a broad band receiver for receiving the high rate PN composite code and further includes a data recovery channel and a tracking loop channel. The data recovery channel comprises a high rate mixer and a low rate mixer for removing the high data rate component code and the low data rate component code to provide a low data rate data stream. The tracking loop channel comprises a high rate early-late tracking system for producing a high rate error signal and further comprises a low rate portion of the tracking loop for producing a low rate error signal which is combined with the data output to provide a clock error signal.

Abstract: An apparatus for adaptive-power control of a spread-spectrum transmitter of a mobile station operating in a cellular-communications network using spread-spectrum modulation. A base station transmits a first spread-spectrum signal. A mobile station has an automatic-gain-control circuit for generating an AGC-output signal, from a received signal. The received signal includes the first spread-spectrum signal and an interfering signal.

Abstract: A method and system for increasing the capacity of radiotelephone communication systems by eliminating interference to communication traffic caused by random access bursts from unconnected mobile station are disclosed. Access slots are provided in CDMA signals by interrupting other communication traffic of mobile stations using the same frequency at periodic intervals. This allows mobile access bursts to be received at a base station without interfering with other traffic.

Abstract: On the transmitter side, data to be transmitted are converted into a plurality of parallel data sets by a serial-parallel converter 101 and spread spectrum modulation is effected by means of PN code generators 105 and selectors 102. Each of the modulated outputs is delayed by a delaying circuit 103 with reference to a sounder channel and the phase thereof. The output thus delayed and the output of the sounder channel are added by an adder 104 to be multiplexed and transmitted.On the receiver side, correlation between a received signal and a reference signal is formed by a correlator 201 to obtain a correlation pulse from the correlation output thus obtained. Data demodulation is effected by means of a sounder detecting circuit 209, a sampling pulse generating circuit 210 and an information detecting circuit 211, starting from this correlation pulse.According to the structure described above, in SS communication, data demodulation can be effected with a high efficiency by using a single correlator.

Abstract: A carrier frequency corrector for a receiver for use in a direct sequence code division multiple access communication system having a carrier frequency consisting of an expected carrier frequency and a carrier frequency error, modulated by a pseudo-noise code. A local frequency source provides a local frequency approximately equal to equal to the expected carrier frequency. A demodulator provides complex demodulated received signals stripped of the pseudo-noise code and mixed with the local frequency source. Each of the demodulated signals consists of in-phase signal components and quadrature signal components and the carrier frequency error. A sampler is coupled to the demodulator and converts the demodulated signal components to digital samples. A digital signal processor is coupled to the sampler and multiplies each signal component sample by stored digitized samples of a plurality of closely spaced sinusoidal tones to provide a product corresponding to each tone.

Abstract: A chaotic transmitter (100) operates according to preselected chaotic protocols, such as a set of Lorenz equations. Modulation is accomplished by modifying a predetermined parameter of the set of chaotic Lorenz equations with a message signal, thereby producing a spread spectrum chaotic transmitted signal. A corresponding receiver (200) reconstructs a synchronizing drive signal, which is used by a demodulator (412) of the receiver (200) to detect the message signal.

Abstract: In a frequency hopped radio communication system wherein a control signal and a speech signal are transmitted together and the speech signal is transmitted via a predetermined set of frequency bands, method and apparatus are provided for converting the control signal into a corresponding RF control signal having a frequency spectrum lying in frequency bands separate from the predetermined set of bands. The frequency bands for the RF control signal may be between the predetermined set of frequency bands for the speech signal and may particularly be within guard bands established between the set of frequency bands for the speech signal.

Abstract: A noise-reduced method of transmitting a video signal including separating the video signal into a plurality of frequency subbands representing a corresponding plurality of subband images, each of which is made up of a corresponding array of blocks of samples; for a preselected one of the subband images, measuring the busyness of each of the blocks of that subband image; for the preselected subband image, assigning each of the blocks of that subband image to one of a plurality of groups, the plurality of groups including a group of more busy blocks and a group of less busy blocks; adaptively modulating the samples of the selected subband image by multiplying the selected subband image by a set of adaptive modulation factors, wherein a greater quantity of adaptive modulation factors is used for the blocks assigned to the group of more busy blocks as compared to the blocks assigned to the group of less busy blocks; and transmitting the adaptively modulated selected subband image along with the set of adaptive m

Abstract: EMI suppression technique that pseudorandomizes the positive or negative going transitions that are used to represent one binary state in a transmitted digital signal such as in an MTL-3 data format. By pseudorandomizing the selection of these transitions, substantial spreading of the spectral energy occurs. Descrambling need not occur since each transition is recognized as the encoded binary state. Thus, the data sender can encode the data and suppress EMI without any changes to the receiver's equipment.

Abstract: A method for allowing a number of wireless transceivers to exchange information (data, voice or video) with each other. A first frame of information is multiplexed over a number of wideband frequency bands at a first transceiver, and the information transmitted to a second transceiver. The information is received and processed at the second transceiver. The information is differentially encoded using phase shift keying. In addition, after a pre-selected time interval, the first transceiver may transmit again. During the preselected time interval, the second transceiver may exchange information with another transceiver in a time duplex fashion. The processing of the signal at the second transceiver may include estimating the phase differential of the transmitted signal and pre-distorting the transmitted signal.

Abstract: A spread spectrum demodulator for use with a phase-shift-keying modulated spread spectrum signal used in mobile satellite communications. An objective of the spread spectrum demodulator is to perform tracking by producing from a correlation pulse signal an error signal having a time discrimination characteristic. The spread spectrum demodulator generates from the correlation pulse signal an error signal whose level varies in response to a phase difference between a pseudonoise signal contained in a received signal and a reference pseudonoise signal. A clock in synchronism with the received signal is generated from this error signal, thereby demodulating the received signal.

Abstract: For protection of communication against interception by frequent pseudorandom changing of the distribution of transmissions on channels, an input distributive switch is installed before the channel division device of a transmitting system and a similar output switch is installed after the channel division device of a receiving system. The distributive switches are controlled by synchronized pseudorandom generators and while the input switch repeatedly changes the distribution of transmissions on channels, and thereby channel of each transmission, the output switch directs all signals of each transmission to a fixed circuit defined for reception of that transmission.

Abstract: A method of transmitting and receiving data packets across a noisy communication medium, e.g., an AC power line. The data packets are transmitted using spread-spectrum chirps. A first sequence of the chirps forms a contention-resolution preamble used by transmitters to resolve conflicting contentions for access to the communication medium. The preamble is followed by a second sequence of chirps that form a start-of-packet symbol used by receivers to delineate the start of data within the packet. To simplify detection at the receiver, identical chirps are used in the preamble and the start-of-packet symbol. To enable the receiver to avoid erroneously interpreting preamble chirps as start-of-packet chirps, and thereby erroneously begin to accept packet data, chirps in the preamble are transmitted at a different pitch (i.e., different time period between inception of successive chirps) from chirps in the start-of-packet symbol.

Abstract: A wireless communication system allow two-full two-way communication among a net or loop of stations. Each station is in direct communication with another member of the net such that a logical communication loop is created about the net. Each station combines its received signal with its own audio signal for retransmission to the next member of the loop whereby audio from said station is passed in turn to each of the other loop members. Transmission frequency hopping is utilized to insure system privacy and minimize interference with or from other loops operating in the same area. The system dynamically reconfigures itself to allow for the addition or dropping of a station without breakdown of the loop.

Abstract: Two, three or more competitive personal communications network spread spectrum systems share spectrum without interfering with each other, without significantly decreasing the chip rate of each PCN system, and without increasing the level of interference seen by fixed service users. A duopoly of spread spectrum communications system includes a first transmitter station, a second transmitter station, a first receiver station and a second receiver station. A transmitter at the second transmitter station transmits a spread spectrum signal on a carrier frequency which is offset from the carrier frequency of the first transmitter at the transmitter station by the chip rate. A tripoly of spread spectrum communication system includes the elements of the duopoly spread spectrum system and further includes a third transmitter station and a third receiver station.

Abstract: A spread spectrum receiving device using a correlator in an IF stage of the receiving device is disclosed, which is so constructed that interference wave or disturbing wave is removed by subjecting the interference wave or the disturbing wave and a desired spread spectrum signal to a signal processing in a stage preceding or succeeding a correlator to take out the desired spread spectrum signal.

Abstract: A method of simultaneously transmitting first and second data signals by the technique of spectrum spreading by direct sequence, comprises using the first data signal to modulate a spreading code produced by a code generator from a code clock and using the second data signal to modulate the delay of the spreading code. Modulation of the spreading code delay comprises either modifying the delay of the code delivered by the code generator, or modifying the code clock frequency. Apparatus for carrying out this method is also described.

Abstract: A receiver operated using a spread spectrum code division multiple access mode includes integrators for respectively integrating two signals of an in-phase channel and a quadrature channel, a comparator for comparing the two integrated signals, and a multiplexer for selectively outputting a signal having the greater magnitude between the two signals of the in-phase and quadrature channels in accordance with the result of the comparison in the comparator. Therefore, one channel outputting a signal having the greater magnitude between the two signals is selected to despread and demodulate the signal, using the regular difference of the outputs from the in-phase and quadrature channels. Thus, the favorable channel conditions can be maintained, and the despreading and demodulating can be simplified.

Abstract: A power control system for a cellular mobile telephone system in which system users communicate information signals between one another via at least one cell site using code division multiple access spread spectrum communication signals. The power control system controls transmission signal power for each cellular mobile telephone in the cellular mobile telephone system wherein each cellular mobile telephone has an antenna, transmitter and receiver and each cell-site also has an antenna, transmitter and receiver. Cell-site transmitted signal power is measured as received at the mobile unit. Transmitter power is adjusted at the mobile unit in an opposite manner with respect to increases and decreases in received signal power. A power control feedback scheme may also be utilized. At the cell-site communicating with the mobile unit, the mobile unit transmitted power is measured as received at the cell-site.

Abstract: A power control system for a cellular mobile telephone system in which system users communicate information signals between one another via at least one cell site using code division multiple access spread spectrum communication signals. The power control system controls transmission signal power for each cellular mobile telephone in the cellular mobile telephone system wherein each cellular mobile telephone has an antenna, transmitter and receiver and each cell-site also has an antenna, transmitter and receiver. Cell-site transmitted signal power is measured as received at the mobile unit. Transmitter power is adjusted at the mobile unit in an opposite manner with respect to increases and decreases in received signal power. A power control feedback scheme may also be utilized. At the cell-site communicating with the mobile unit, the mobile unit transmitted power is measured as received at the cell-site.

Abstract: Communication apparatus and method that includes generating a series of successive spread-spectrum chirp signals, which are progressively swept within a defined bandwidth. The chirps are divided into two frequency-swept portions, one beginning at an intermediate frequency within the bandwidth being swept to one end of the frequency range of the chirp, and a second beginning at the other end of the frequency range and being swept to the intermediate frequency. This has the effect of moving the frequency transition from the boundaries of the chirp to its center, with the result that the discontinuities introduced at the boundaries by phase reversals due to successive modulated chirps generate less out-of-band energy.

Abstract: In a preferred embodiment, a method for excising narrow band interferers in a spread spectrum signal communication which includes the steps of: receiving the spread spectrum signal; digitizing the spread spectrum signal; transforming the digitized signal from the time domain to the frequency domain; discarding the magnitude of the digitized signal and replacing it with a normalized value; and transforming the digitized signal back to the time domain.

Abstract: A transceiver for transmitting and receiving spread spectrum signals having an adaptive threshold for distinguishing between valid receive data signals and noise. The transceiver includes a transmitter for transmitting spread spectrum signals and a receiver for receiving spread spectrum signals. A correlator correlates a received signal against an expected receive pattern. The correlation of the received signal is compared to a threshold value. If the correlation exceeds the threshold value, a carrier detect signal is generated. The number of false carrier detect signals occurring within a pre-determined period of time is determined. The threshold value is varied according to the number of false carrier detects.

Abstract: A spread spectrum communications system for use over a communications channel, including a transmitter-generic-chip-code generator, a transmitter-message-chip-code generator, an EXCLUSIVE-OR gate, a combiner, a transmitter, a receiver-generic-chip-code generator, a generic mixer, a generic-bandpass filter, a receiver-message-chip-code generator, a message mixer, a message-bandpass filter, and a synchronous detector. The transmitter-generic-chip-code generator generates a generic-chip-code signal and the transmitter-message-chip-code generator generates a message-chip-code signal. The EXCLUSIVE-OR gate spread-spectrum processes message data with the message-chip-code signal to generate a spread-spectrum signal. The combiner combines the generic-chip-code signal with the spread-spectrum signal. The transmitter transmits the combined generic-chip-code signal and spread-spectrum signal, on a carrier signal over the communications channel as a spread-spectrum-communications signal.

Abstract: A spectrum diffusion communication receiving apparatus includes a first generating unit for generating a reference code, a second generating unit for generating a reference signal in synchronism with the reference code, a correlating unit for obtaining a correlation between a received signal and the reference code, and a decoding for decoding the received signal in accordance with the reference signal and a correlation output from the correlating unit.

Abstract: For use in a spread spectrum communication system there is provided in an embodiment of the invention a spread spectrum transmitter which uses a voltage controlled oscillator (VCO) for generating a carrier signal wherein the frequency of the oscillator is controlled by the output of a correlation code generator and data generator coupled to a varactor in the oscillator. The use of a VCO eliminates the need for sidelobes associated with mixers. In another embodiment the separation of the output of the correlation code generator and data generator coupled to the varactor and the output of a phase detector coupled to the varactor simplifies tuning of the transmitter and in another embodiment the use of a high gain differential amplifier to couple the output of the correlation code generator and data generator to the varactor eliminates tuning the transmitter.

Abstract: A power control system for a cellular mobile telephone system in which system users communicate information signals between one another via at least one cell site using code division multiple access spread spectrum communication signals. The power control system controls transmission signal power for each cellular mobile telephone in the cellular mobile telephone system wherein each cellular mobile telephone has an antenna, transmitter and receiver and each cell-site also has an antenna, transmitter and receiver. Cell-site transmitted signal power is measured as received at the mobile unit. Transmitter power is adjusted at the mobile unit in an opposite manner with respect to increases and decreases in received signal power. A power control feedback scheme may also be utilized. At the cell-site communicating with the mobile unit, the mobile unit transmitted power is measured as received at the cell-site.

Abstract: A spread spectrum receiver correlator for a with filters matched to transmitter chip codes are implemented in digital circuits along with a digital circuit for acquisition and tracking of the arrival times of the chip codes. The digital circuit implementations are used for the noncoherent demodulation of pulse position spread spectrum modulation signals where the pulse is a carrier modulator by a chip code and for the noncoherent demodulation of multiple chip code modulation signals where each information symbol is represented by one of several chip codes modulating a carrier.