Abstract: A spread spectrum receiver uses a comparison of the magnitude of the code correlation amplitudes at equal power at a one chip spacing to the magnitude at a central position there between to determine if multipath interference is present. The lead or lag error from constructive or destructive multipath interference may also be determined. Inaccuracies due to such interference may then be corrected or minimized by, for example, determining the residual code phase error and/or the prompt or accurate code phase delay.

Abstract: A code acquisition device securing reliable code acquisition and reducing a time required for a code acquisition procedure. In the device, a sampler samples an input signal, and a searcher continuously searches for a spreading code used for the sampled signal until the phase of the spreading code is acquired. A verifier verifies whether the phase of the spreading code used for the sampled signal is acquired, according to the search result of the searcher. The searcher initializes and restart the verifier whenever the phase of the spreading code is searched.

Abstract: The invention relates to a method for acquiring a receiver (1) into a code modulated spread spectrum signal received by the receiver (1). In the method at least one replica code (r) is used which corresponds to a code used with the modulation having a pre-determined number of chips, and an examination phase is performed, in which a frequency shift of the signal within a selected frequency area is examined, and a code phase of the code used with the modulation is examined. In the method the frequency shift examination is divided into a first estimation phase and a second estimation phase, wherein in the first estimation phase the selected frequency area is divided into a first set of frequencies, and in the second estimation phase a second set of frequencies is examined nearby each frequency of the first set of frequencies.

Abstract: A method and apparatus for computing a convolution between an input GPS signal and a C/A code reference by generating the convolution result in real time without storing unprocessed signal samples. The apparatus comprises a vector multiplier running at high speed to achieve the same result as a vector multiplier sized to process an entire epoch. Additionally, the input samples to, and the output samples of, the vector multiplier can be quantized to reduced circuit complexity.

Abstract: A collection of wirelessly networked devices including first devices wirelessly networked together using a first wireless protocol that is a frequency hopping protocol, and second devices wirelessly networked together using a second wireless protocol, are operated in a coordinated manner, including proactive reduction of interference between the networked devices. In one embodiment, the first devices include at least a first and a second subset operating with a first and a second frequency hopping pattern respectively. The proactive reduction effort includes synchronized operations of the first and second subsets of the first devices, and the second devices operate in a manner complementary to the synchronized operations of the first devices. In one embodiment, the collection of wirelessly networked devices includes at least one wireless device that operates in both wireless networks in accordance with both wireless protocols.

Abstract: A channel estimation method for a digital telecommunication station is disclosed. A frequency correction burst is sought by scanning of the wanted channel. The frequency correction burst is used to provide coarse time and frequency synchronizations. A synchronization burst is received. Calculating the cross-correlation of the expected training sequence with the training sequence contained in said synchronous burst to obtain a channel estimate. A frequency error estimate is derived from the channel estimate, and the frequency error of the received burst is corrected in accordance with said frequency error estimate. The received synchronous burst is equalized. The frequency corrected symbols are used to refine the time and frequency synchronizations.

Abstract: A subscriber unit (104) listens to a first channel (202) comprising a plurality of micro-slots and a plurality of data units. The subscriber unit decodes at least a portion of a data unit on the first channel comprising a micro-slot value. The subscriber unit learns the synchronization between the first channel and a second channel (206/300) based on the micro-slot value. A first base radio (1061) transmits a first plurality of data units on the first channel. A second base radio (1063) transmits a second plurality of data units on the second channel. The first plurality of micro-slots on the first channel are synchronized with the second plurality of micro-slots or plurality of frame boundaries on the second channel. The first base radio transmits a message (406) on the first channel in at least one of the plurality of data units, wherein the message comprises at least a micro-slot value used to associate the synchronization between the first channel and the second channel.

Abstract: In a code division multiple communication system which prevents the dropout of a whole packet and does not require the generation of a carrier from a received signal, under bad communication path, by generating an orthogonal code with chip synchronization from a correlation peak of a synchronization code sequence output from a surface acoustic wave matched filter, a preamble division of a spectrum spread signal is composed of plural synchronization burst. Each synchronization burst is composed of a synchronization packet division having the Barker code of 11 chips and a dummy division. The period of one synchronization burst (Tburst) is set equally to the period of one symbol in a data division (Tsymbol) which is modulated by the orthogonal sequential code of 64 chips. When the correlation peak of at least one from among plural synchronization code sequences is detected, the orthogonal code can be generated in accordance with the start timing of the first symbol in the data division.

Abstract: A synchronizing circuit synchronizes a predetermined code with first and second codes different in phase, include: a code generating part outputting phase-shifted code shifted in phase by a predetermined number of chips from the predetermined code; a first correlation detecting part detecting a correlation between the phase-shifted code from the code generating part and the first code; a second correlation detecting part detecting a correlation between the phase-shifted code from the code generating part and the second code; and a code shifting part shifting the phase of the phase-shifted code from the code generating part by a predetermined number of chips according to the detection results of the first and second correlation detecting parts.

Abstract: A circuit for detecting a serial signal comprises a first circuit (400) coupled to receive the serial signal (200) during a predetermined plurality of time periods of substantially equal duration. The first circuit is coupled to receive a first code (414). The first circuit is arranged to compare a part of the serial signal corresponding to each time period of the plurality of time periods to the first code, thereby producing a match signal. The first circuit accumulates the match signal from each of the each time period of the plurality of time periods.

Abstract: A multiple phase shift keying (MPSK) spread spectrum communications receiver uses weighted correlation techniques for carrier recovery and tracking. The receiver includes three subsystems: a synchronization system, a carrier tracking system, and a data demodulation system. To demodulate the received signal, the receiver requires a carrier frequency that matches the frequency of an associated transmitter as well as the sampling (or chip) and symbol clocks that are synchronized with those of the transmitter. In the disclosed receiver, the carrier tracking subsystem continually tracks the carrier frequency of the received signal using a tracking scheme that uses weighted correlation techniques. The weighted correlation technique combines signals from two correlator modules, an R-correlator module and a W-correlator module, to generate the correlation output. The R-correlator is similar to conventional correlators. The W-correlator, however, is unlike conventional correlators.

Abstract: A satellite digital audio radio system (SDARS) transmitter provides a broadcast transmission signal including a time division multiplex (TDM) mode of transmission and a coded orthogonal frequency multiplex (OFDM) mode of transmission. The SDARS transmitter provides a transmission signal that supports four transport mechanisms or traffic channels: (1) multiple audio and data program channels (program channels), (2) a cluster control information channel (CC), (3) a global control information channel (GC), and (4) a synchronization channel (CS). In particular, the SDARS transmitter processes 100 program channels into 5 clusters, each cluster comprising GC and CS information, along with a program cluster comprising 20 program channels and CC information. The SDARS transmitter further partitions each cluster into 255 cluster segments and interleaves the cluster segments from each cluster for transmission.

Abstract: An improved tracking system, illustrated as a delayed lock loop. The time intervals of a communication signal are tracked by first sampling the communication signal. A standard and a sample, advanced relative to each other by i sample positions from a sample position representing an assumed arrival position ta of a time interval, are correlated over a correlating length of k samples. Also, the standard and a sample retarded relative to each other by the i sample positions from the assumed arrival time ta are also correlated over k samples. A timing error is determined from the correlations. A predication of the arrival time tp of the next interval is determined from the error. One or more of the correlation length k or the i sample position is modified based on the predicated arrival time tp. The process is repeated using any of the modified correlation length k and/or sample position i. The timing error may also be used for descrambling and despreading.

Abstract: A device and a method for equalizing data delays in a multiplicity of serial input data streams switched by a switching network in a telecommunication switching system, wherein the multiplicity of data word synchronization units are used for synchronizing a multiplicity of input data streams at a data word level into a multiplicity of synchronized parallel input data streams.

Abstract: A device tracks multipath components of a spread-spectrum signal. The spread-spectrum signal has an associated chip code sequence. The device receives multipath components of the spread-spectrum signal. A first and second plurality of multipath components are despread about a center code phase. The first plurality is a sequence of multipath components prior to the center code phase and the second plurality is a sequence of multipath components after the center code phase. A first and second combined energy is determined from the first and second plurality of multipath components. A tracking delay is calculated based on a difference between the first and the second combined energies. The center code phase is adjusted by said tracking delay.

Abstract: A novel design of, and method of operation for, a coherent delay lock loop (DLL) for communication systems that employ a pilot channel or pilot symbols is disclosed. Pilot information is used to produce an estimate of signal phase and thereby remove the need for the magnitude operation within the DLL arms. The disclosed design and method afford better time-tracking performance by avoiding the squaring loss (due to the magnitude operation) encountered in noncoherent DLL designs. Alternative embodiments disclose designs and methods that are robust to signal amplitude variation. A first alternative normalizes a DLL error signal by a computed estimate of the squared magnitude of the pilot signal. A second alternative normalizes the error signal using only the early and late signals and therefore is applicable for noncoherent DLL designs as well as coherent DLL designs.

Abstract: A method and apparatus having a modified Reed-Solomon decoder is used for finding a specific code group used by a base station and the frame timing synchronization with the base station. The modified Reed-Solomon decoder uses a standard Reed-Solomon decoder and some reliability measurements computed from the received code word symbols. If the reliability of a received symbol is too low, this symbol is considered as erasure. By selecting code word symbols with higher reliabilities and erasing code word symbols with lower reliabilities, the symbol error probability is reduced and the performance is improved. Several modified Reed-Solomon decoders and a few decoding strategies are introduced in order to decode the received code word sequences with a power- and memory-effective method.

Abstract: A method (50) of operating a communications receiver (20). The method receives a communications signal (10) which is transmitted via a channel, where the communications signal comprises received known pilot data (DP) and received information data (DI), the known pilot data and information data being sequentially transmitted. The method then estimates a first channel impulse response (52) for the channel, wherein the first channel impulse response is in response to the received pilot data. Next, the method determines (54) a group of estimated information data in response to the first channel impulse response. Next, the method estimates a second channel impulse response (56) for the channel in response to the estimated information data. Thereafter, the method forms (56) a combined channel impulse response for the channel, using differing weights as applied to the first and second channel impulse responses.

Abstract: A method for tracking a locally generated spread spectrum signal sequence includes the step of correcting the spread spectrum signal sequences with respect to the synchronization time in an early/late interval. The correlation responses are subtracted from one another and the clock of the locally generated spread spectrum signal sequence is controlled as a function of the subtraction. Correlations are performed through the use of at least two hierarchically staggered closed-loop controls having different early/late intervals. The early interval of the one closed-loop control having a small early/late interval must not become earlier than the early interval of the other closed-loop control system having a next-larger early/late interval. Furthermore, the late intervals of the one closed-loop control system having a small early/late interval must not become later than the late interval of the other closed-loop control system having a next-larger early/late interval.

Abstract: A method and apparatus for computing a convolution between an input GPS signal and a C/A code reference by generating the convolution result in real time without storing unprocessed signal samples. The apparatus comprises a vector multiplier running at high speed to achieve the same result as a vector multiplier sized to process an entire epoch.

Abstract: A method is disclosed for processing mobile-originated random access requests in a mobile telecommunications system that randomly selects new signatures for re-transmissions in the event that collisions have occurred. As such, the random access re-transmissions are randomized over the signature domain instead of just over the time domain. Consequently, the disclosed invention significantly shortens random access delays caused by collisions or erroneous arrivals at base station receivers, and also significantly reduces the interval between random access re-transmissions.

Abstract: A method and apparatus for improving bit error performance within a hard decision radio interface processing environment is provided, whereby a sampling unit collects a number of samples per channel symbol of an input signal to generate a number of sampling streams, and a correlator computes a correlation value of each of the number of sampling streams with a predetermined bit sequence. The correlation values are fed into a threshold comparator which utilizes a variable threshold value to generate threshold comparator values or trigger output values. By examining a set of trigger output values, a phase decision unit determines the optimum sampling timing or sampling phase.

Abstract: A transmission method using synchronous reverse links establishes synchronization by controlling transmission times of mobile stations according to synchronization control messages received through a control channel and then controlling the transmission times according to synchronization control bits received through a traffic channel.

Abstract: Short pseudo-random (PR) probing sequences that comply with ITU V.90 digital impairment learning (DIL) descriptors provide DIL probing sequences that yield high performance in severe inter-symbol interference (ISI) channels. The short PR sequences do not require the insertion of extra zero symbols to get rid of ISI. Further, a novel receiving structure corrects for propagation of digital impairment common in conventional equalizers for an ISI free receipt of the probing sequences within the strictly time constrained probing sequence. Based on the reliably received signals, general digital impairment mapping tables, digital pads, regular and strange RBS patterns, and different types of PCM codecs (A-law/&mgr;-law) are identified.

Abstract: An orthogonal frequency division multiplexed wideband communication system provides improved time and frequency synchronization by inserting an unevenly spaced pilot sequence within the constellation data. A receive correlates the received data using the unevenly spaced pilot sequence. The pilot sequence is generated with a maximum length pseudo random noise code and inserted into frequency bins having prime numbers.

Abstract: In a mobile station terminal apparatus during connection of a call, the received energies of pilot signals transmitted from neighbor base stations in a CDMA system are monitored. Upon disconnection of the call, a process of pilot signal detection is executed repeatedly and preferentially in order from an Active Set of pilot signals having great received energies, on the basis of the result of monitoring the received energies of the pilot signals during connection of the call, whereby the mobile communication terminal apparatus is enabled quickly and efficiently to receive signals from the base stations in the same CDMA system and can be quickly placed again in the waiting state ready to accept a mobile communication service.

Abstract: A method, system and device for code-phase tracking and/or carrier tracking the broadcast signal streaming a spread spectrum signal using an adaptive and time variant digital filter based on an AutoRegressive (AR) model of a Maximum Entropy Method (MEM) algorithm for signal filtering. Alternatively, the Maximum Likelihood Method, the Minimum Variance Method or any statistical method can be used in the adaptive filter for noise filtering. The method and device use a code generator to produce a replica of a PRN code and at least two correlators to separately perform signal correlation between the PRN replica and the received spread spectrum signal in order to extract the code signal for code-phase tracking, and the carrier signal for signal tracking. One or more A/D converters are used to convert the received spread spectrum signal into a digital signal so that signal filtering can be performed digitally. A demodulating step is used to extract the message from the received signal.

Abstract: When a mobile communication unit (e.g. a cellular telephone) is powered up, the unit must lock on to a local base station, or “acquire” a base station signal, to enable the user to send and receive calls. To lock on a local base station, the mobile unit must determine the delay at which the base station is sending the pseudo random (PN) code. This process is called the “acquisition.” The current art of acquiring a base station involves collecting a set of samples at a particular code phase, or delay, testing the collected sample, and repeating these steps using another code phase until the correct code phase is found. The present invention discloses a method and apparatus for collecting a set of samples at a particular code phase, and simultaneously testing the collected sample and collecting the next set of samples for another code phase.

Abstract: A system and method for generating random numbers in a wireless communication network is presented. The noise present in the signal received by a wireless receiver is extracted to form random numbers. Wireless transmitters typically are identified by a synchronization signal. In acquiring the synchronization signal, a wireless receiver generates a plurality of psuedorandom sequences, despreads an incoming signal, integrates the resulting signal, and performs an energy computation to calculate an energy measure. One or more energy measures are collected in a pool of bits, and the bits are hashed to extract random numbers.

Abstract: A receiver in a communications system is operated by receiving a radio communications signal transmitted by a station of the communications system and generating a correlation output representing a correlation of the received radio communications signal and a subsequence of a modulation sequence that is selected based on a correlation between the selected subsequence and the modulation sequence. The receiver is then synchronized based on the generated correlation output. The selected subsequence preferably has an optimal out-of-phase correlation with the modulation sequence. According to an aspect of the present invention, the selected subsequence has a minimum out of phase correlation with the modulation sequence in comparison to other subsequences of the modulation sequence. For example, the selected subsequence may have a “minimum maximum” out-of-phase correlation value, a “minimum aggregate” out-of-phase correlation metric, or a combination thereof.

Abstract: A data file (22) having a plurality of frames is received, with each frame having a syncword. A data string (52) including a plurality of potential syncwords (54) is identified in the data file (22). One of the potential syncwords (54) is randomly selected. A subsequent potential syncword address is determined based on the selected potential syncword (54). Whether a subsequent potential syncword exists at the subsequent potential syncword address is determined. The data file (22) is decoded based on the subsequent potential syncword in response to the subsequent potential syncword existing at the subsequent potential syncword address.

Abstract: A system and method are provided for achieving slot synchronization in a Wideband CDMA system in the presence of large initial frequency errors. A FSC matched filter having a reduced coherence window is provided for reducing degradation of a symbol due to carrier phase rotation resulting from oscillator error, thereby preventing severe loss of signal energy at the peaks of the FSC matched filter output. Additionally, a circular sliding integrator is provided to combine the accumulated disbursed signal energies due to the oscillator error and multipath interference, thereby allowing easier identification of the time index representing the time slot boundary. Further, a sorter is provided for determining a predetermined number of time index candidates representing the time slot boundary, thereby increasing the possibility that the true time index boundary is sent to the second stage of synchronization.

Abstract: A method of acquiring a communications signal is provided. The method includes the steps of storing a forward chirp sync segment (106) of an auto-correlating forward chirp sync (102) and storing a reverse chirp sync segment (108) of a symmetric auto-correlating reverse chirp sync (104). A header comprising of either a forward chirp sync FCS (102) or a reverse chirp sync RCS (104), a predetermined number of data blocks comprising a data frame (308), and the symmetric auto-correlating trailer is received. The header, the data blocks, and the symmetric trailer are susceptible to frequency error. The method correlates the FCS segment (106) with the auto-correlating FCS (102) to provide a FCS correlation signal (312) and correlates the RCS segment (104) with the auto-correlating RCS (108) to provide a RCS correlation signal (314). The method determines the frequency error, symbol timing, and frame timing based upon the FCS correlation signal (312) and the RCS correlation signal (314).

Abstract: An apparatus and method for phase modulating SYNC codes transmitted over downlink pilot time slots DwPTSs when a primary common control physical channel P-CCPCH is transmitted using transmit diversity in an NB-TDD CDMA mobile communication system. The apparatus and method transmits and receives the P-CCPCH signal using the transmit diversity by providing a diversity indicator for changing phase variation of the SYNC codes included in the DwPTSs.

Abstract: Codes to be detected can be identified at high speed. The supply of the data shift clock (DCLK1) to be given to the matched filter (82) is stopped at desired timing to hold the received signal (S10) and replica code generated at the correlation coefficient generator (83) is switched to the first, second or third replica code at desired timing to detect the correlation value of that time. Thereby, the second code, the third code and the first code are detected in order to detect the timing and the code type of the first code. Therefore, each correlation detection can be conducted at the same timing since the matched filter conducts the correlation detection at high speed holding the received signal and thus, the first code included in the received signal can be identified at higher speed than before.

Abstract: When a request is generated for shift from continuous to intermittent reception, the mobile-station transmitter/receiver calculates a start timing of a slot allocated thereto (Tstart), compares it with a concurrent time when the request has been generated (Tnow), and when it is not possible to have a time of preparation required for starting a reception in the slot by the start timing of a nearest slot (Tstart), the mobile-station maintains the continuous reception until the slot ends (Tend).

Abstract: A multiple access, spread-spectrum communication tracking system includes apparatus which tracks a centroid of a transmitted code-division multiplexed (CDM) code sequence that is contaminated with multipath distortion. The apparatus includes an analog to digital converter which digitally samples the spread-spectrum channel signal to produce a sequence of sample values. The sample values are divided into a set of even-numbered sample values which correspond to early multipath signal components and the set of odd sample number values which correspond to the multipath signal components. The centroid tracking receiver generates a plurality of local code sequences, each of which is a code phase-shifted version of the transmitted code sequence. The centroid tracking receiver correlates each of the locally generated code sequences with the odd and even numbered sample values, respectively, to produce a group of early despread multipath signals and a group of late despread multipath signals.

Abstract: The present invention is a channel-aided, decision-directed delay-locked loop (CADD-DLL) implemented, in one embodiment of the present invention, for pilot-symbol-aided (PSA) code-division multiple-access (CDMA) communication. In one embodiment of the present invention initial pseudo-noise (PN) code acquisition is accomplished with the aid of a conventional non-coherent PN code acquisition system, and, upon acquiring the initial PN code epoch, PN code tracking is performed using a channel-aided, decision-directed PN code tracking mechanism. The tracking loop in accordance with the present invention includes delay and advance PN correlators. The correlators are followed by data and phase correction as well as amplitude matching devices, the outputs of which are subtracted to form an error signal for code tracking purposes.

Abstract: For synchronisation purposes, a transmitter (TX) multiplexes a pilot carrier with carriers whereon data elements (DATA) are modulated, and transmits the pilot carrier together with the modulated carriers to a receiver (RX). The immunity of the pilot carrier from interference, such as radio amateur signals, is improved by modulating the pilot carrier with a non-constant signal, for instance a random signal, an alternating signal or even scrambled data elements (DATA), before transmission thereof. Since demodulation of the pilot carrier in the receiver (RX) and averaging successive demodulated pilot carriers reduces the effect of the interference induced on the non-constantly modulated pilot carrier, the degradation of the synchronisation between transmitter (TX) and receiver (RX) is reduced significantly.

Abstract: A multi-carrier transmission system, for example a DMT system. Channel information is transmitted between two transceivers using a plurality of subcarriers. Each subcarrier, or symbol, has a parameter associated with it. The transceivers are adapted to transmit the channel information as a sequence of n groups in which each of the n groups contains information concerning the number of adjacent subcarriers which have the same value as the parameter, together with the actual value of the parameter. The parameter which may have a plurality of discrete values, may be a bit-loading value, or a QAM constellation identifier.

Abstract: In a first embodiment of the invention, a concatenated preamble code is formed by a kronecker product between two subcodes of the same or different lengths. The subcodes have favorable correlation properties and may be Barker codes, minimum peak sidelobe codes, Gold codes, Kasami codes, Boztas codes, or other codes. At the receiver a two-stage processor is used to detect the concatenated preamble code. The two-stage processor comprises a series of two filters, one of which is preferably a mismatched filter. In another aspect of the invention, a repeated codeword preamble is formed from a series of the same repeated short subcode. The short subcode may be an augmented or truncated odd-length code. At the receiver a single matched filter is preferably used to generate a series of spikes separated by the period of the subcode. An alert/confirm detector non-coherently adds together individual correlation spikes and reject false alarms.

Abstract: A method of, and frame synchronizing device for, synchronizing systems having a digital interface. The systems are synchronized by extracting frame time information from a signal transferred from an external source through a digital interface, generating a frame reset signal, delayed by predetermined time based on the extracted frame time information, and resetting the entire systems based on the generated frame reset signal. Also, the color burst signal is free-oscillated during the digital interface mode in order to accommodate to the frame reset signal, which has a variable period.

Abstract: A method and apparatus reduces current consumption of a mobile communication unit, such as a cellular or mobile telephone that communicates with a base station by disabling a temperature controlled crystal oscillator and a code generator while the mobile communication unit is in a sleep mode of operation, thereby reducing the sleep mode current consumed by the mobile communication unit. Prior to entering sleep mode, the mobile communications unit stores the state of the code generator and disables the temperature controlled crystal oscillator. Upon waking from sleep mode, the mobile communication unit calculates what the state of its code generator would have been if its temperature controlled crystal oscillator had not been disabled, and uses this calculated state to achieve synchronization with a code generator in the base station.

Abstract: A circuit comprising a first counter, a second counter, a third counter and a decoder, where the decoder may be configured to present a locked output signal. The first counter may present a first output signal in response to a start of frame signal and one or more control signals. The second counter may be configured to present a second output signal in response to the start of frame signal and the first output signal. The third counter may present a tracking control signal to the first counter in response to one or more of the control signals.

Abstract: A method of chip interleaving in direct sequence spread spectrum communications. A binary code sequence is chosen to have a length N=2k−1 and to be self-orthogonal. A data string of M=QN+1 bits, QN−1 bits, or QN+S bits, where Q is a positive integer and S is an integer between 1 and N that lacks a common factor with N, is multiplied sequentially with the binary code sequence until N chip frames of M chips each are produced. These chip frames are transmitted to a receiver, and recovered in an equally straightforward manner. The integers Q and N are chosen according to transmission conditions.

Abstract: A method of superimposing additional information on a video signal, transmitting it, and detecting the additional information from the transmitted video signal. The additional information is synchronized with a sync signal in the video signal, and generated in N(N≧1) unit intervals of one field of the video signal. Some predetermined unit intervals of the additional information generated in N(N≧1) unit intervals of one field of the video signal, are phase-inverted. The additional information is identified by detecting the information in unit intervals based on the sync signal in the video signal, and detecting that information in some predetermined unit intervals is inverted. The additional information is identified by detecting the information in unit intervals, and integrating the detection results with the information in inverted predetermined unit intervals inverted.

Abstract: In a conventional data transmission and receipt apparatus using PN flags according to PN sequence, there has occurred a flag emulation due to a bit stream similar to a PN flag in a frame of the data stream, which disables transmission of the frame therebetween. To solve the problem, the data transmission and receipt apparatus of the present invention inserts a mark representing that there is laid a bit stream similar to the PN flag into the frame while the data receipt apparatus distinguishes such a bit stream from the PN flag. Thereby, the data receipt apparatus is capable of receiving the frame involving the bit stream similar to the PN flag without occurrence of a flag emulation.

Abstract: A receiver is provided for use in a spread spectrum communication system for receiving a spread spectrum signal having a modulated PN code, the receiver including: an analog-to-digital converter for sampling an input signal in synchronization with a first clock signal, and generating a sampled signal. The first clock signal having n times a frequency of a chip clock signal.

Abstract: A scramble control method allowing synchronization of scramblers and descramblers without resetting them per frame is disclosed. The scramblers are simultaneously reset and the descramblers are simultaneously reset. The scramblers are simultaneously initialized at a first time point and thereafter tire not reset. The descramblers are simultaneously initialized after an elapse of a time period required for transferring a frame from an input interface to an appropriate output interface through the switch, and thereafter the descrambler are not reset. Alternatively, a scrambler state indicating a pseudorandom pattern is generated at predetermined intervals and is sent to the scramblers and the descrambler.

Abstract: A synchronization circuit with correlated signal is capable of generating synchronizing signals to provide a stable correlated signal when correlation processing is conducted by digital sampling and/or even when multiplexing is conducted and a low spread factor is preset in the direct spread spectrum telecommunication system. A discriminator compares a correlated signal represented by the root of the sum of the squares of the input signals with a predetermined threshold. A processing unit generates a signal when an output which does not exceed the threshold in a unique delay interval preset in a multiplexing block so that one output signal is obtained in one period of spreading. An initial synchronization circuit establishes a synchronization relationship between signals from the processing unit. A synchronization counter causes either of a correct lock counter or error lock counter to operate via a determining unit to synchronizing pulses in a synchronization relationship with correlation.