786 results about "Quadrature modulation" patented technology

An apparatus includes: an affine transformer that subjects input complex IF signals I(t) and Q(t) to affine transformation according to affine transformation coefficients, and outputs compensated signals a(t) and b(t); a quadrature modulator that applies quadrature modulation on a local oscillation signal according to the compensated signals, and outputs a modulated signal (RF transmission signal); a quadrature detector that removes a carrier component from the modulated signal and outputs complex feedback signals I′ (t) and Q′ (t); and a control portion that extracts linear distortions remaining in the complex feedback signals I′ (t) and Q′ (t) as plural distortion coefficients (DC offsets of the I-phase and the Q-phase, an IQ gain ratio, and a deviation in orthogonality), and updates the current affine transformation coefficients in accordance with updating equations including the distortion coefficients to set updated affine transformation coefficients again in the affine transformation portion. It is thus possible to constantly update the distortion compensation coefficients most appropriately under operating conditions.

The transmitter of the transceiver includes: a transmitter-side mixers of a transmitter-side modulator; a transmitter-side voltage-controlled oscillator; and a transmitter-side divider. The divider having a dividing factor of a non-integral number is supplied with an oscillating output of the oscillator. A pair of non-quadrature local signals having a phase difference of 90° plus a predetermined offset angle is produced by the divider and supplied to the mixers. The transmitter includes a phase-shift unit which converts a pair of quadrature transmit signals having a phase difference of about 90° on an analog basis into a pair of non-quadrature shifted transmit signals. Consequently, quadrature modulation is performed by the mixers. Use of a similar configuration enables the reduction in interference of an RF signal with local signals supplied to receiver-side mixers of the receiver.

A wireless communication apparatus receives an quadrature modulated signal, generate a local signal having a frequency different from a center frequency of the quadrature modulated signal, performs quadrature demodulation on the quadrature modulated signal by using the local signal, to obtain an I channel signal and a Q channel signal, performs Fourier transform on the I channel signal and the Q channel signal, to obtain signals in a frequency domain, and calculates a first correction coefficient for correcting phase distortion and amplitude distortion caused by the quadrature demodulation by using pairs of signals among the signals, each of the pairs are located at symmetrical frequency positions with respect to the frequency of the local signal.

Disclosed are an apparatus and a method for transmitting uplink control information in an OFDMA communication system. The method, in which the uplink control information is transmitted using an ACK channel in the OFDMA communication system, includes the steps of receiving data bits of the uplink control information, outputting transmit symbols of sub-carriers by performing orthogonal modulation with respect to symbols for codewords of the received data bits, and inverse fast fourier transforming and transmitting a transmit signal including bundles of sub-carriers allocated the modulated transmit symbols.

An apparatus and method for compensating for an analog quadrature modulation (AQM) error in a linearization apparatus for AQM-modulating a digital predistorted signal and outputting the AQM-modulated signal through a high-power amplifier. In the apparatus and method, a gain/phase error estimator predicts a gain/phase imbalance error caused by AQM on the predistorted signal. A Direct Current (DC) offset estimator predicts a DC offset for a feedback signal from the high-power amplifier. An error compensator compensates for the digital predistorted signal for a DC offset signal output from the DC offset estimator, and then compensates for a gain/phase error output from the gain/phase error estimator.

An optical device includes, a first Mach-Zehnder modulator that produces a first output, and a second Mach-Zehnder modulator which produces a second output. A splitter couples the first and second Mach-Zehnder modulators. A combiner combines the first and second outputs. A phase shifter is coupled to the first and second Mach-Zehnder modulators. The first Mach-Zehnder modulator, second Mach-Zehnder modulator, splitter, combiner and the phase shifter are each formed as part of a single chip made of electro-optical material. Such two similar optical device integrated together with polarization combiner provide a two-polarization performance.

A method for generating a global positioning signal from a space based craft including the steps of generating a plurality of binary modulating signals using a waveform generator; separately modulating an in-phase component of a desired carrier of the global positioning signal to be generated with at least a first binary, modulating signal selected from the plurality to generate at least one corresponding in-phase modulated signal component; separately modulating a quadrature component of the carrier with at least a second binary modulating signal selected from the plurality to generate at least one corresponding quadrature modulated signal component; and, combining the at least one in-phase modulated signal component and the at least one quadrature modulated signal component to generate the global positioning signal; wherein the global positioning signal has a constant envelope.

A high-frequency transmission signal is transmitted from a transmission antenna with a predetermined transmission period, and a signal of a reflected wave reflected from a target is received by a reception antenna. A code generator generates a first code sequence and second code sequence that constitute a pair of complementary codes. A first modulator modulates the first code sequence to generate a first transmission signal. A second modulator modulates the second code sequence to generate a second transmission signal. A quadrature modulator performs quadrature modulation by using the generated first and second transmission signals. The high-frequency transmission signal is generated from a signal that is quadrature modulated, and transmitted from the transmission antenna.

A constant amplitude coded bi-orthogonal demodulator demodulates the received constant amplitude bi-orthogonal modulated data, cancels the parity bits to generate the serial data, detects the occurrence of an error by dividing the demodulated data into a plurality of groups of data, outputs the serial data as demodulated data if an error does not occur, sequentially converts bit polarities of data of groups in which an error occurs if the error detector detects the error, compares distances between the received bi-orthogonal modulated data and the constant amplitude coded bi-orthogonal modulated data, and selects, as demodulated data, data of which corresponding bit polarities are changed according to the comparison results. According to the present invention, power consumption is reduced, a power amplifier can be manufactured at an inexpensive cost, interference robustness can be ensured, and data can be transmitted at a high transmission rate and a variable transmission rate.

This invention provides a receiver in which the calibration time by repeated operations to correct phase mismatch and amplitude mismatch between I and Q signals can be reduced. The receiver comprises mixers which convert received RF signals into quadrature modulated IF signals, signal paths which filter and amplify and output the quadrature modulated signals output from the mixers, a calibration circuit which calibrates phase and amplitude mismatches between the I and Q components of the quadrature modulated signals output through the signal paths, a frequency converter which, when the mixers or the signal paths selected output calibration signals with IF frequency instead of the quadrature modulated signals, converts the calibration signals into those with a frequency higher than IF frequency, and an arithmetic operation circuit which calculates phase and amplitude mismatches from the calibration signals output by the frequency converter and outputs calculation results. The calibration circuit executes calibration, using the calculation results.

A coherent adaptive subcarrier modulation system applies subcarrier modulation to quadrature modulated signals with constant envelope modulation suitable for efficient sinewave and squarewave subcarrier modulations. The quadrature subcarrier enables the addition of new signals to the in-phase and quadrature phase signals with spectral isolation in the Global Position System while maintaining a constant envelop amplitude.

A simple and efficient method to measure base-band gain and phase imbalance as well as orthogonality phase imbalance in a quadrature (IQ) modulator (12). The method comprises estimating values of modulator gain and phase imbalances (34) while the modulator is operational, by inputting at least one test signal at a base-band frequency 2 fi and computing the imbalances based on the 2 fi term, the computed imbalances then used in normal transmit operation to generate a pre-distortion transformation on the transmit signal to generate an imbalance compensation. The method can be easily expanded to cope with frequency dependent base-band amplitude and phase imbalance. This feature has an advantage when the transmitted signal is a multi-carrier signal, as the compensation can be adapted for each individual carrier.

To provide an orthogonal frequency division multiplex modem circuit which can multiplex signals, whose bit rates and QoS are different from one another, and can transmit the signals via one OFDM line. A serial/parallel converter converts input signals into a complex parallel signal respectively, and a sub carrier and a modulation system are assigned every communication channel. A randomizer changes the alignment sequence of the signal, a discrete inverse Fourier transformer processes the signal, a parallel/serial converter converts the signal into a serial signal, and a transmitter performs the orthogonal modulation of the signal to output the signal from an antenna. A receiver performs orthogonal demodulation of the signal received with an antenna, a serial/parallel converter converts the signal into a parallel signal, and a discrete Fourier transformer processes the parallel signal. In addition, a de-randomizer restores the alignment sequence of the subcarriers into the original condition, and a parallel/serial converter decodes and outputs the signal.

The invention provides a general satellite navigation signal interference source and a signal generating method thereof. The general satellite navigation signal interference source is mainly composed of a main control software module, an intermediate frequency interference signal generating module and a radio up-conversion circuit. The method mainly comprises the steps of: according to the control parameters of the interference signal input by users as interference mode, frequency points, bandwidth and power and the like, processing digital frequency synthesis to generate low-intermediate frequency digital signals, processing digital orthogonal up-conversion and D/A conversion for the low-intermediate digital signals, to attain intermediate frequency analogue signal output. The invention utilizes phase lock frequency synthesis theory to generate the local oscillation frequency of corresponding frequency points, mixes the radio frequency local oscillation signal of the local oscillation frequency and the intermediate frequency analogue signals via an orthogonal modulation, processes automatic gain control and accurate power control to output the attained radio frequency interference signals. The invention can simulate the interference condition of a receiver actually receiving satellite signals.

The invention discloses a method and a system for orthogonal modulation of power signals. The method comprises the following steps: acquiring an initial sequence length and an initial sequence according to a frequency lower limit, a preset sampling frequency and an initially set integer signal cycle number of a power signal; acquiring a reference frequency according to the initial sequence, and further acquiring a unit cycle sequence length and a preset sequence length; acquiring first forward and reverse sequences according to a preset sequence starting point and the preset sequence length; generating first real-frequency and imaginary-frequency vector sequences and second real-frequency and imaginary-frequency vector sequences according to the first forward and reverse sequences; converting obtained first and second phases into a first forward sequence average initial phase; obtaining a new preset sequence starting point according to the average initial phase; and obtaining a cosine function modulation sequence and a sine function modulation sequence according to second forward and reverse sequences obtained from the initial sequence. By adopting the method and the system of the invention, an orthogonal modulation sequence with consistent amplitude height can be obtained, and the accuracy and anti-jamming performance of sinusoidal parameter calculation are improved.

A data separating unit separates data to be transmitted into the number of data equal to that of antennas. An error correcting unit performs a coding for error correction on data. An interleave unit interleaves data after the convolutional coding. A preamble adding unit adds an STS to the head of a burst signal. The preamble adding unit, corresponding respectively to a plurality of transmitting antennas, is to store respectively a plurality of STSs to be transmitted in a predetermined period. An IFFT unit performs Inverse Fast Fourier Transform. A GI unit adds a guard interval to data in time domain. A quadrature modulation unit carries out quadrature modulation. A frequency conversion unit performs a frequency conversion. An amplification unit is a power amplifier for amplifying radio-frequency signals. Finally, signals are transmitted from the plurality of transmitting antennas.

A chaos spreading code c(n) is inputted to a spreading unit 32. Data D1 and c(n) are multiplied in the spreading unit 32. A chaos spreading code d(n) is inputted to a spreading unit 42. Data D2 and d(n) are multiplied in the spreading unit 42. The chaos spreading codes c(n) and d(n) orthogonally cross each other. Outputs of the spreading units 32 and 42 are added by an adder 35 and transmitted through a transmitting unit 36 to a transmission path 38. By making an initial value which is set in a chaos sequence generator having a construction of a digital circuit different, the chaos spreading codes which orthogonally cross can be formed. Since the chaos spreading codes c(n) and d(n) orthogonally cross, an orthogonal modulating unit having a construction of an analog circuit for amplitude-modulating carriers which orthogonally cross can be made unnecessary and the construction can be simplified.

The present invention relates to a method for coding the hybrid automatic repeat request channel. The method comprises the steps of executing code block dividing to the inputted transmission block according to the maximum allowed coding block of the coder; adding CRC bit to each sub-transmission-block generated after dividing; executing channel encoding to each newly generated sub-transmission-block; executing code rate matching to each subcode stream generated after coding; combining or cascading each subcode stream after code rate matching; executing channel interweaving to the combined or cascaded code stream; mapping the base band of the binary system bit stream after channel interweaving to the planisphere under corresponding modulation mode or orthogonally modulating to the carrier wave; and mapping the modulation symbol to the resource of physical channel. This method increases the performance of chain circuit through making that the coding block has enough diversity gain by configuring the code block cascading before the channel interweaving, and furthermore makes that the transmission has good enough error detection capability and the retransmission time of the coding block is reduced by configuring the CRC bit adding after the code block dividing.

The invention discloses a self-adapting analog quadrature modulation unbalance compensating method and a device thereof. The device of the invention comprises a baseband signal module, a DPD module, a self-adapting analog quadrature modulation AQM compensator, a local oscillation (LO) and a RF transmission channel, and a feedback channel. The method of the invention comprises the steps that: an AQM compensation algorithm and a control unit are used for transmitting a training sequence signal to firstly judge whether a DAC is provided with quadrature modulation compensator QMC; then pre-distorted baseband si (t) and a sq (t) signal and baseband IB and a QB signal sent by a feedback loop are obtained, and then measured and compared; the particle swarm optimization (PSO) is applied to continuously adjusting the 6 compensating parameters until a target function reaches the global minimum; at last, a compensating parameter is applied to the QMC unit updated parameter to conduct a dynamic compensating process to the pre-distorted baseband si (t) and sq (t) signals, therefore, the AQM self-adapted unbalance compensation can be realized, and the performance of a broadband digital pre-distorted system is improved.

Disclosed is a quadrature demodulator for high-speed wireless communication, which comprises: an A/D converter for converting received signals into digital signals; a signal recovery unit for recovering carriers and symbol timing from the signals converted by the A/D converter; a decision unit for detecting recovered signals output by the signal recovery unit, and performing a decision process on them; an I/Q gain imbalance detector for detecting gain imbalances of the I and Q-phase components from the recovered signals, and outputting an I/Q gain compensation value for compensating for the gain imbalances; and an I/Q gain compensator, provided between the A/D converter and the signal recovery unit, for reflecting the I/Q gain compensation value output by the I/Q gain imbalance detector to the received signals.

An apparatus and method for transmitting uplink fast feedback information using a fast feedback channel in an orthogonal frequency division multiple access (OFDMA) communication system. A channel encoder generates uplink fast feedback information to be transmitted, and outputs codewords designed such that a minimum Hamming distance between the codewords is maximized, according to the uplink fast feedback information. A non-coherent modulator performs orthogonal modulation on transmission symbols corresponding to the codewords and allocates the orthogonal-modulated transmission symbols to subcarrier cluster. An inverse fast Fourier transform (IFFT) block performs IFFT on a transmission signal having the subcarrier cluster and transmits the IFFT-processed transmission signal.

A Quadrature Amplitude Modulation (QAM) method and apparatus including a QAM transmit modulator with at least one unbalanced mixer, which creates an asymmetric two-dimensional (2-D) QAM symbol constellation. The asymmetrical symbol constellation provides baseband symbol clock signal leakage sufficient to facilitate quick and simple baseband symbol clock recovery and signal channel compensation at the QAM receiver without significantly degrading the system bit-error rate (BER). While slightly degrading static BER, overall system performance is improved when considering baseband symbol clock recovery and received signal compensation for an imperfect signal channel. This allows QAM to be deployed in systems where QAM is otherwise prohibitively expensive and improves overall system performance for any existing QAM system application without additional bandwidth, cost or complexity.

A method and apparatus reduces error in a communication system that includes multiple orthogonal subcarriers by suppressing a subcarrier in a transmitting communication device and by equalizing a received signal in a receiving communication device. Subcarrier suppression is based on a determination of a signal quality metric with respect to each subcarrier or is based on a determination of excessive signal power overdriving an amplifier of the receiving communication device. Equalization of the received signal is based on an equalization function that reduces a multipath delay introduced to the transmitted signal when the multipath delay exceeds a tolerable multipath delay.