Abstract: A receiver comprises a demodulator to estimate channel impulse response and timing synchronization information for the received signal and to select a modulation technique for demodulating the received signal; and a channel decoder to produce a binary sequence from the received signal demodulated according to the selected modulation technique; wherein the demodulator: demodulates the received signal according to a first modulation technique and a second modulation technique to produce a first demodulated signal and a second demodulated signal, respectively; calculates a minimum distance between a first reconstructed signal including the training sequence and the first demodulated signal to estimate the channel impulse response and timing synchronization information; calculates a minimum distance between a second reconstructed signal including the training sequence and the second demodulated signal to estimate the channel impulse response and timing synchronization information; compares the minimum distance co

Abstract: A differential receiver which provides for estimation and tracking of frequency offset, together with compensation for the frequency offset. Estimation and tracking of the frequency offset is undertaken in the phase domain, which reduces computational complexity and allows frequency offset estimation and tracking to be accomplished by sharing already-existing components in the receiver. Compensation for the frequency offset can be performed either in the time domain, before differential detection, or in the phase domain, after demodulation, or can be made programmably selectable, for flexibility.

Abstract: An apparatus and method for generating piecewise linear phase transitions during a phase transition interval of a first signal to control controlling the phase/frequency of a second signal. The initiation point, duration and shaping parameters of the piecewise linear phase transitions are selected to control adjacent channel emissions in the second signal.

Abstract: An aircraft transponder comprises an antenna for receiving an RF signal a downconverter coupled to the antenna for downconverting the RF signal to an IF signal, an analog-to-digital converter coupled to the downconverter to digitize the IF signal to produce a digital signal, and; a processor unit coupled to the analog-to-digital converter. The processor unit is configured to: (1) generate a delayed digital signal; (2) multiply a delayed digital signal by the digital signal to produce a multiplied output; and (3) filter the multiplied output to produce a filtered output having a positive or negative sign. The transponder further includes a sign converter operable to output a one or zero based on the sign of the filtered output to recover the data component.

Abstract: A base station demodulator according to the exemplary embodiment of the present invention includes a vector index demodulator, and a channel value detector. The vector index demodulator demodulates CQI or ARQ ACK/NACK channels by multiplying QPSK modulation signals transmitted as m subcarriers in a tile by m conjugate complexes corresponding to the m subcarriers, and determines the greatest value of the demodulation results as a vector index. The channel value detector inputs n vector indexes demodulated by the vector index demodulator to a first shift register, inputs n subsequent vector indexes to a second shift register, and detects a channel value for the CQI or the ARQ ACK/NACK by repeating the above vector index input to the first and second shift registers m-times.

Abstract: Systems for suppressing image noise are provided. In this regard, one embodiment includes a system for suppressing image noise comprising a low noise amplifier (LNA) configured to amplify a received RF signal, an RF variable gain attenuator with an image rejection filter with programmable bandwidth configured to suppress image noise and image interference, and an RF mixer configured to perform frequency translation.

Abstract: A quadrature amplitude modulation (QAM) signal generator, which can obtain optical signals such as QAM signals without handling multilevel electrical signals, can be produced by using a plurality of parallel Mach-Zehnder modulators (MZMs), such as quadruplex parallel MZMs (QPMZM). The quadrature amplitude modulation (QAM) signal generator includes a first waveguide, a first quadrature phase-shift-keying (QPSK) signal generator provided on the first waveguide, a second waveguide connected with the first waveguide at a wave-combining point, and a second quadrature phase-shift-keying (QPSK) signal generator provided on the second waveguide.

Abstract: A method and apparatus are provided for combining pilot symbols and Transmit Parameter Signalling (TPS) channels within an OFDM frame. The method uses Differential Space-Time Block Coding to encode a fast signalling message at an OFDM transmitter. At an OFDM receiver, the encoded fast signalling message can be decoded using differential feedback to recover information about the channel responses that would normally be carried by pilot symbols. In wireless data transmission employing adaptive modulation and coding, an instantaneous channel quality measurement, independent of the origin of interference for example, neighboring-cell interference, white thermal noise, or residual Doppler shift is provided. Using the correlation between a signal which has been symbol de-mapped, and one which has also been soft decoded and re-encoded, a channel quality indicator is produced. Another embodiment uses TPS data as pilot symbols by decoding TPS and then re-encoding.

Abstract: Where the additional data throughput is added using an amplitude offset or a combination of phase and amplitude offset, the legacy differential demodulator does not recover the amplitude information. The present invention provides a method for demodulating amplitude offsets in a differential modulation system in order to recover the amplitude information. The demodulated amplitude information may be used to recover the additional Level 2 data transmitted as an amplitude offset or combination phase and amplitude offset in a differential multiple phase shift keying (D-MPSK) transmission, such as across adjacent OFDM symbols and/or adjacent frequency subcarriers.

Abstract: A quadrature-multiplexed continuous phase modulation (QM-CPM) signal is made up of the real parts of two underlying CPM signals whose information content can be recovered from just their real parts. The real parts of two such signals are I/Q multiplexed and transmitted onto a single channel to approximately double the bits/Hz of the underlying CPM signals, while maintaining the same or similar minimum distance. A class of QM-CPFSK (QM-continuous phase frequency shift keyed) signals are presented that use binary signaling but more phase states, and M2-ary QM-CPFSK signals are derived from constant envelope M-ary CPFSK signals. M2-ary multi-amplitude CPFSK signaling schemes are constructed that maintain the same distance as known multi-amplitude CPFSK schemes, but more than double the bandwidth efficiency in bits/Hz. In addition to these CPFSK based embodiments, embodiments are provided that more generally use CPM, non-continuous phase modulated signals, and even trellis-based PAM based signals.

Abstract: An apparatus for determining the amount of skew to be injected into a high-speed data communications system of including a plurality of lanes having a data bus per lane, relative to a reference lane, for system skew compensation. By knowing the relative amount of skew that each lane requires for alignment, an appropriate amount of skew can be injected on each lane to provide alignment and thus compliancy with the SFI-5 and SxI-5 standards, in terms of data skew specifications. The relative skew amounts for each transmitting lane are determined using a methodology involving internal loopback and characteristics from a connected communications element to the chip receive path.

Abstract: A method for enhancing the Bluetooth transmission speed and robustness of an emitting end and a receiving end is provided. The method is utilized in a system having an emitting end and a receiving end, wherein at least one of the emitting and receiving ends is provided with BlueSPEED-PSK or BlueSPEED-DELTA-PSK (adapted Gray coded D16PSK) modulation with optional FEC.

Abstract: A wireless communication system may include a first wireless communications device, and a second wireless communications device. The first wireless communications device may include a wireless transmitter, and a modulator coupled to the wireless transmitter for modulating input data to generate a Gaussian phase shift keyed signal having a selected data symbol mapping. The second wireless communications device may include a wireless receiver, and a demodulator coupled to the wireless receiver for demodulating the Gaussian phase shift keyed signal using memory-less symbol decisions based upon the selected data symbol mapping.

Abstract: Modulator system (1) comprising modulators (2, 3, 4) for modulating input signals (A) according to different modulation schemes (8PSK, GMSK) cause discontinuities in the output signals (F) when switching between the schemes. By providing the modulator systems (1) with compensators (13, 22-26) for compensating amplitudes/phases of the output signals (F) of the modulator system (1) for discontinuities, these discontinuities resulting from modulation scheme changes are reduced to a large extent. This may be done before/after the pulse shapers (11, 21). The compensators (13, 22-26) comprise multipliers for multiplying pulse shaped modulated signals with complex valued waveforms (E), or for multiplying modulated signals with waveforms (S, T), or for multiplying complex valued signals (B, C, D) with complex valued phase offsets (X, Y, Z), which complex valued signals (B, C, D) are to be multiplied with mapped input signals.

Abstract: The invention relates to an orthogonal frequency division multiplexing system with PN-sequence. In the synchronization of the invention, both timing offset and frequency offset are estimated and compensated by utilizing a time and frequency synchronization device. In addition, the PN-sequence with the cyclic prefix is added to the OFDM symbol before transmitting. The time and frequency synchronization device of the invention comprises two synchronization circuits from the cyclic prefix and PN-sequence when calculating the timing offset and frequency offset of receiving signal. As a result, the OFDM system of the invention not only has better performance in fading channel, but also has the better bandwidth utilization without extra bandwidth for transmitting the PN-sequence.

Abstract: At a base station apparatus, known pilot signals for use in channel estimation are transmitted, and in addition thereto MCS pilot signals that are used to perform adaptive modulations respectively corresponding to a plurality of modulation schemes are multiplexed and output. A mobile station apparatus dispreads the respective MCS signals out of the multiplex signal, compares these to known symbols patterns, and sends the MCS pilot signals that show a matching relationship to the base station apparatus as a mobile station reception result. Upon receiving the mobile station reception result from the mobile station apparatus, the base station apparatus selects the modulation scheme of the optimum modulation level for the downlink signals. This configuration makes it possible to switch the modulation schemes in an accurate and simple way.

Abstract: A system and method for processing a received Global Positioning System (GPS) signal into a processed position finding GPS signal and for processing a first and a second input signal jointly with the GPS signal. A modulator and transmitter for modulation and transmission of processed signals in cellular systems and in mobile network, wherein cellular system and mobile network are distinct. A modulator and transmitter for transmission of processed signals in a satellite system and in a cellular system. Multiple Input Multiple Output (MIMO) transmitter and receiver having a transmit filter and a receiver filter wherein the transmit and receiver filter are mismatched. A modulator and transmitter which comprise cascaded hybrid systems, including a cascaded GSM or EDGE, of cascaded infrared (IR) or GSM or CDMA or TDMA or UMTS systems and contain Radio Frequency identification (RFID) signals.

Abstract: A method and an apparatus for generating a differential quadrature phase shift keying (DQPSK) code optical signal are provided. The method may includes splitting an optical signal to obtain two polarized optical signals, modulating and phase-shifting one of the two polarized optical signals to obtain a phase-shifted and polarized optical signal, and modulating the other of the two polarized optical signals to obtain another polarized and modulated optical signal. The phase-shifted and polarized optical signal may be combined with the other polarized and modulated optical signal to obtain a polarization multiplexed optical signal. The method may further include, polarizing the polarization multiplexed optical signal to obtain the DQPSK code optical signal. The apparatus may include a polarization beam splitter (PBS), modulators, a phase-shift controller, a polarization beam combiner (PBC), and a polarizer.

Abstract: Methods, apparatus, and systems for alternating quadratures differential binary phase shift keying (AQDBPSK) modulation and demodulation radically increase overall energy efficiency of a communication system due to the combined effect of efficient utilization of transmitter power, high noise immunity of modulation and demodulation, fast synchronization, and simple implementation. Efficient utilization of transmitter power is achieved because radical reduction of side lobe regeneration provided by AQDBPSK allows operation of all amplifiers of the transmitter analog signal path, including power amplifiers, in energy efficient nonlinear mode (for example, they can operate as class C amplifiers) without causing interchannel interference. AQDBPSK radically reduces side lobe regeneration by limiting phase transitions between adjacent in time modulator output symbols to .+?.90.degree and smoothly executing the transitions.

Abstract: In one embodiment, a receiver of the invention has a detector coupled to a digital processor. The detector is adapted to mix the received PSK signal with a local oscillator (LO) signal having a time-varying phase offset with respect to the carrier frequency of the PSK signal to produce a digital measure of the PSK signal.

Abstract: The present invention relates to a communication field and particularly to a method and apparatus for transmitting/receiving multimedia broadcast/multicast data based on hierarchical modulation in order to solve the problem of low efficiency of conventional methods.

Abstract: In a blind detection apparatus and method capable of determining a modulation mode by comparing the absolute values of the real and imaginary parts of a sequence of intersymbol phase differences between symbols separated from each other at an interval of four symbols (instead of comparing intersymbol phase differences of symbols at an interval of one symbol as in the related art), the symbols being included in a training sequence code of a received normal burst. Therefore, a number of calculations for the blind detection may be decreased e.g., by a factor of four, and as a result, the time for performing the blind detection may be decreased. In addition, the hardware design for the blind detection may be simplified.

Abstract: At transmission, the data to be transmitted is divided into N data blocks, these N blocks are processed in parallel in N M-ary orthogonal keying (MOK) modulation channels, each modulation using a group of spread codes, each channel emitting a signal. All of these signals are transmitted in series. At reception, the signal received is processed in N M-ary orthogonal keying (MOK) demodulation channels, and the blocks obtained are grouped together in series.

Abstract: Techniques for sending a transmission in a manner to reduce peak-to-average power ratio (PAPR) of the transmission are described. A transmitter may select phases for a plurality of resource blocks based on a metric, e.g., PAPR. The transmitter may apply the selected phases to modulation symbols to be sent on the resource blocks. In one design, the transmitter may select one phase for each resource block and may apply the phase to all modulation symbols to be sent on the resource block. In another design, the transmitter may select multiple phases for multiple spatial layers in each resource block, one phase for each spatial layer. The transmitter may then apply each phase to all modulation symbols to be sent on one spatial layer in one resource block. For both designs, the transmitter may generate at least one OFDM symbol or at least one SC-FDMA symbol based on the modulation symbols after applying the selected phases.

Abstract: A signal transmitter apparatus generates three phase-shifted signals by shifting three transmission signals by predetermined phase shift amounts so that the phase shift amounts of the transmission signals are different from each other by 120 degrees. The signal transmitter apparatus generates three combined transmission signals and outputs the three combined transmission signals to the three transmission conductors, respectively, by combining each of pairs of the phase-shifted signals such that an inverted signal of a first phase-shifted signal is combined with a second phase-shifted signal, when each of the pairs of the phase-shifted signals includes the first and second phase-shifted signals among the three phase-shifted signals and phase shift amounts of the first and second phase-shifted signals are different from each other by 120 degrees.

Abstract: A modulation and demodulation system capable of minimizing a bit error rate in a six-phase phase modulation method. A senary signal phase-modulated and outputted by a modulator is received and phase-modulated by a destination demodulator to a binary signal before conversion by the modulator. The modulator assigns (0, 0), (0, 1), (0, 2), (1, 2), (1, 1) and (1, 0) which are senary signals (bi, ti) to first to sixth phases respectively. The demodulator performs a conversion process from the senary signals to the binary signals, for instance, by storing transmitted senary signals and sequentially converting every senary signal of length m to binary signal of length b so as to output them. The process of the demodulator assigns the first to sixth phases as the senary signals (bi, ti) to (0, 0), (0, 1), (0, 2), (1, 2), (1, 1) and (1, 0) respectively.

Abstract: A method is provided for specifying a transmission mode for each signal portion of a multi-carrier signal transmitted between a first and second device. The method includes defining an adaptive modulation and coding set divided into a plurality of subsets, each of the plurality of subsets including a plurality of transmission modes for transmitting a signal portion. The method further includes selecting a transmission mode subset from the plurality of subsets for transmission of the multi-carrier signal from a first to a second device, selecting a signal portion transmission mode for each signal portion from the plurality of transmission modes of the selected transmission mode subset, defining semantic bits that indicate the selected transmission mode subset, defining an indicator bit for each signal portion indicating the selected sub-carrier transmission mode, and transmitting the semantic bits and the indicator bit for each signal portion from a first to a second device.

Abstract: A communication system for transmitting encoded signals over a communication channel is disclosed. The system includes a transmitter, which has a source that is configured to output a plurality of input signals. The transmitter also includes an encoder that is configured to generate a plurality of output signals in response to the plurality of the input signals to output a code word according to the plurality of output signals, wherein the code word has a predetermined algebraic construction for space-frequency coding based upon the communication channel being characterized as a frequency selective block fading channel. Further, the transmitter includes a modulator that is configured to modulate the code word for transmission over the communication channel, and a plurality of transmit antennas that configured to transmit the modulated code word over the communication channel.

Abstract: A circuit including an analog to digital converter and a processor is disclosed. The analog to digital converter may be configured to generate a plurality of samples from a received signal in response to a reference signal. The processor may be configured to designate one of an early sample of the samples and a late sample of the samples as an ideal sample in response to a first timing error of an on-time sample of the samples being greater than one-half a sample period of the received signal.

Abstract: Systems and methods for transmitting and receiving additional data, such as video data, over legacy satellite digital audio radio signals are provided. In exemplary embodiments, hierarchical modulation can be used to transmit secondary information over a legacy signal. For example, the Sirius Satellite Digital Audio Radio Service (“SDARS”) system may use a second layer of modulation to transmit video data on top of its regular audio signal. In order to support such future services within the original system design, sometimes referred to herein as a “legacy” system, additional information bandwidth can be acquired, for example, by using hierarchical modulation to overlay data for such new services on top of the legacy transmission. In such a system, for example, overlay data can be transmitted by applying a programmable angular offset to legacy QPSK symbols, for forming a new constellation similar to 8PSK.

Abstract: The system and method enable simpler analog processing in a transmitter by reducing the number of bits in a digital signal through delta sigma modulation. Selection of current sources in a digital to analog converter of the transmitter is done using a randomization circuit.

Abstract: A mixer circuit accumulates I signal (digital signal of first channel) having its band limited by low-pass filter and first carrier signal to perform two-phase shift keying modulation thereon. An adder adds fundamental-wave component of bit clock signal BCK into Q signal (digital signal of second channel) having its band limited by the another low-pass filter to obtain a resultant added-up signal. Another mixer circuit accumulates the added-up signal and second carrier signal to perform two-phase shift keying modulation thereon. Output signals of the mixer circuits are input to another adder so that they may be added up to obtain a QPSK signal as a modulated quadrature signal. The QPSK signal contains frequency signals whose frequencies are a sum of bit clock frequency and carrier frequency and a difference between them. When demodulating, the carrier signal and the bit clock signal are reproduced using the frequency signals.

Abstract: The transmission system is backward compatible with a former transmission system (DVB-T), enabling a receiver of the former system to receive signals transmitted by a transmitter of the new transmission system. A new modulation is used to transmit additional information bits corresponding to a new service. The new modulation is specified by a combination of the former modulation with a new-built over modulation.

Abstract: Method and apparatus for implementing LDPC codes in an IEEE 802.11 standard system configured to operate in a Multiple-Input, Multiple-Output (MIMO) schema. A method in accordance with the present invention comprises defining a base LDPC code, having a length equal to an integer number of data carriers in an ODFM symbol, transmitting the base LDPC code over a plurality of sub-carriers, wherein the base code is transmitted at an expected phase on sub-carriers specified by the IEEE 802.11 standard system, and transmitting the base LDPC code on other sub-carriers than those specified by the IEEE 802.11 standard system, wherein the base LDPC code on the other sub-carriers is transmit offset in phase from the base LDPC code on the specified sub-carriers.

Abstract: An optical sender is disclosed that operates in a Differential Quadrature Phase Shift Keying modulation scheme for high speed optical transmission and is capable of performing logical calculations at a low speed. The optical sender transmits a Differential Quadrature Phase Shift Keying (DQPSK) signal generated with modulation signals ?k and ?k so that a signal directly output from a signal receiver corresponding to the optical sender is in agreement with data signals Ik and Qk to be transmitted. The signal receiver is capable of modulation by DQPSK, and the modulation signals ?k and ?k are precoded by using the data signals Ik and Qk and the modulation signals one symbol earlier (?k?1 and ?k?1) . The optical sender includes plural precoders that perform logical calculation simultaneously and in parallel on plural data signals one period after another period.

Abstract: A method and a power control device moving the resynchronisation point within the guard period to coincide with a calculated reduction in the RF PA power level such that the spurious frequency products are attenuated as much as possible and moved to be as central as possible within the guard period such that neither the previous burst nor the next burst are affected.

Abstract: Systems and methods for wireless transmission of uncompressed HDTV signals are disclosed. In one embodiment, a method for transmitting an uncompressed HDTV signal over a wireless RF link, comprises providing a stream of regenerated data from the uncompressed HDTV signal; providing a first clock signal synchronized to said stream of regenerated data; encoding said stream of regenerated data, producing a stream of encoded data; providing a second clock signal synchronized to said stream of encoded data; demultiplexing said stream of encoded data, using said second clock signal, into an I data stream and a Q data stream; modulating a carrier with said I data stream and said Q data stream; and transmitting said carrier in a signal over the wireless RF link.

Abstract: A network device comprises a PSK modulator that PSK modulates a header portion of a data packet at a first effective throughput and that PSK modulates outbound data at a second effective throughput to form a PSK modulated payload. A symbol modulator symbol modulates the outbound data at a third effective throughput to form a symbol modulated payload. A modulation selection unit forms a payload portion of the data packet based on at least one of the PSK modulated payload and the symbol modulated payload.

Abstract: A multiple-input multiple-output code division multiple access (MIMO-CDMA) wireless communication equipment has a transmitter and a receiver. The transmitter has an encoder for receiving and encoding a plurality of data, and sending the data to a quadrature phase-shift keying (QPSK) unit. The QPSK unit conducts QPSK modulating to an output of the encoder and sends it to a space-time block coding (STBC) unit or a space multiplexer to process space-time coding or space coding. A plurality of data frame generating modules generate a data frame respectively based on the output of the STBC unit, a plurality of preamble codes generated by a preamble code spreading unit, a pilot code and a cyclic prefix. The data frame is sent to the receiver via a plurality of transmitting antennas.

Abstract: A method for transmitting data in the form of pulse sequences, including a signal synchronization step carried out by a receiver of dataframes DF, in the course of which at least one time window ?T(0) is scanned in search of the beginning PSB of a pulse sequence. The time window is then subdivided into a predefined number of sub-windows ?T(1). The sub-windows are then scanned during further signal detection steps until the beginning PSB of the pulse sequence has been detected within one of the sub-windows which will then be substituted for the previous time window AT(0), until the width of the resulting sub-windows becomes smaller than a predetermined minimum width.

Abstract: Systems and methods for wireless transmission of uncompressed HDTV signals are disclosed. In one embodiment, a method for communicating an uncompressed HDTV signal over a wireless RF link includes providing a clock signal synchronized to the uncompressed HDTV signal; providing a stream of regenerated data from the uncompressed HDTV signal, the clock signal being synchronized to the stream of regenerated data; demultiplexing the stream of regenerated data using the clock signal into an I data stream and a Q data stream; modulating a carrier with the I data stream and the Q data stream; and transmitting the modulated carrier over the wireless RF link. The synchronized clock signal may be provided using a clock and data recovery (CDR) component.

Abstract: Carrier phase detector for calculation of a feedback signal (D) for a carrier phase loop in a receiver, which loop detects a phase error (??) between a phase (?in) of a received signal (Ein), which comprises a sequence of received data symbols, and a nominal phase (?nom) of a nominal data symbol (Enom), with the carrier phase detector in each case calculating the feedback signal (D) as a function of the real part and of the imaginary part of a received data symbol (Ein) , with a received data symbol (Ein) whose phase is in a boundary phase area being weighted gradually to a lesser extent during the calculation of the feedback signal (D), with the boundary phase area in each case being arranged symmetrically with respect to a mid-phase (?mid) which is located in the centre between the two nominal phases (?nom) of equidistant nominal data symbols (Enom), and having a phase extent which is determined by a boundary phase (?g).

Abstract: A digital filter with equalizers and a corresponding method for optimizing a linear equalizer of an RF transceiver determining filter characteristics of the specified analog filter, determining total signal filtering of the RF transceiver based upon a discrete time model of the specified analog filter and upon characteristics of the digital filter, determining an inverse of the determined total signal filtering; multiplying the inverse of the determined total signal filtering with the determined total signal filtering and optimally matching the desired equalizer filtering characteristic with an IIR magnitude equalizer to determine an optimal approximation of a magnitude response of the discrete time model of the specified analog filter. Thereafter, the method includes adding an inverse of the optimal approximation of the magnitude response and optimally matching the pre-distorting group delay response of the filter to obtain an optimal approximation to the pre-distorting group delay response of the filter.

Abstract: The invention relates to a method for dividing the bit rate of QPSK signals by splitting the spectrum of said QPSK signals into at least two channels having band-limited filters in the modulator and demodulator. The prefiltered QPSK signal is split into at least one real and at least one imaginary spectrum at the transmitter end, is transmitted in frequency multiplex, and the filters in the modulator of the transmitter and the demodulator of the receiver are dimensioned according to the transmission function.

Abstract: The present invention relates to a system for communicating between two integrated circuits (ICs) or within an IC. The ICs are either on the same circuit boards or on different circuit boards with a common backplane. The system comprises a first integrated circuit having an output circuit for generating phase shift keying signals and a second integrated circuit having an input circuit for decoding the phase shift keying signals. The output circuit may include a ring oscillator for generating multiple clock signals that are phase-locked to one another.

Abstract: A method and system for generating a composite binary phase shift keying (BPSK) code from two independent component BPSK codes that is representative of the two component BPSK codes. In one implementation the method involves gain weighting each of the first and second component BPSK codes by its respective code power ratio to form first and second gain weighted codes. The first and second gain weighted codes are processed in accordance with an algorithm to form a composite BPSK code. The composite BPSK code has a fifty to seventy-five percent probability of matching each one of the BPSK codes. A system for generating a composite BPSK code from two BPSK codes is also disclosed.

Abstract: Methods and systems for communicating in a wireless network may distinguish different types of packet structures by modifying the phase of a modulation constellation, such as a binary phase shift keying (BPSK) constellation, in a signal field. Receiving devices may identify the type of packet structure associated with a transmission or whether the signal field is present by the phase of the modulation constellation used for mapping for the signal field. In one embodiment, the phase of the modulation constellation may be determined by examining the energy of the I and Q components after Fast Fourier Transform. Various specific embodiments and variations are also disclosed.

Abstract: Briefly, a method and apparatus to calculate cross-correlation values of complex binary sequences are provided. The apparatus may include a transformation unit and a cross-correlator. The cross-correlator may include a cross-correlation controller to provide, based on a type bit and a sign bit, a real component and/or an imaginary component of signals of complex binary sequences to a real accumulator and/or to an imaginary accumulator.

Abstract: This invention presents a coding method for binary digits coding and its circuit for digits transmission. With this coding method, the binary digits are corresponding to a sequence of pulse groups. The binary digits “0” and “1” are corresponding to the two pulse groups with same defined number of pulses and with two special defined pulse frequencies respectively. The two pulse groups have the same defined number of pulses. The number is at least 2. The corresponding decoding method divides the sequence of pulse groups, according to the same defined number, into a set of pulse groups. The duration time of each pulse group is measured. The binary digits “0” and “1” are corresponding to the differences of the duration time of the pulse groups.

Abstract: In a timing component extractor for a digital modulated signal, a frequency converting section 30 receives a complex baseband signal having a symbol rate fs and formed from an I signal and a Q signal, and converts frequency components ±fs/2, which are present in the complex baseband signal as the data changes, to frequency components ±fs/4. The I signal and Q signal of the complex baseband signal are then nonlinearly processed. In other words, multipliers 31, 32 square the I signal and the Q signal, respectively, and an adder 33 adds the respective results of the multipliers 31, 32. A BPF 34 extracts the frequency components ±fs/2 from the output of the adder 33, and outputs the extracted frequency components ±fs/2 as a timing signal. Accordingly, processing can be conducted at a sampling frequency which is twice the symbol rate fs. Moreover, timing extraction can be stably conducted without being affected by a carrier frequency offset.