97 results about "Residual carrier" patented technology

The invention discloses a fully-digital direct sequence spread spectrum communication system and a rapid pseudo code capturing method thereof. A digital signal is processed by using an FPGA (Field Programmable Gate Array) which comprises a pseudo code capturing module, a sampling signal of an ADC (Analog To Digital Converter) is subjected to frequency mixing with a signal of a local carrier NCO (Numerically Controlled Oscillator) and filtered to obtain a baseband signal, residual carrier Doppler frequency is eliminated from the baseband signal by adopting a differential multiplying mode, thus the phase deviation of a receiving signal and a local pseudo code is further obtained through an FFT (Fast Fourier Transform) algorithm without scanning on a carrier frequency domain; and when the phase deviation of the pseudo code is obtained, a local pseudo code phase is modified and is subjected to correlation degree of dissociation with the receiving signal, and the carrier Doppler frequency is figured out by using the FFT algorithm, and is compensated to a carrier NCO and a pseudo code NCO, thus carrier frequency capturing and pseudo code capturing are realized.

This invention provides a method and device to correct remaining frequency offset of the carrier wave and to fix phase and amplitude deviation. First, separately compare the channel parameters of each pilot frequency of the sub-carrier wave at the OFDM data symbol and the channel parameters of each pilot frequency of the sub-carrier wave at No. REF2 training symbol to check the changes in the channel parameters of the data symbol of the pilot frequency of the sub-carrier wave compared to that of the REF2 training symbol. Then divide these values into two paths, to seek the average of the virtual part and the real part of one path, to seek the modulus of the other path first and then to seek the average of the modulus. Then the result of the first path divides its own modulus and then multiples the result of the second path, the value of which is finally divided by the value of each sub-carrier wave in the symbol and the compensation is completed. This method is easy to be implemented and can correct a polarity of deviations affecting OFDM data symbol. And as long as the position of the pilot frequency of the symbol is symmetric, the influence on the estimation result caused by sampling clock deviation can be completely offset or compensated, thus has high practical value.

The invention provides a method with the QoS requirement for distributing resources in a CR OFDM system, which comprises the following steps: selecting a cognitive user whose gamma m is maximal from a to-be distributed cognitive user set UM, distributing the proper sub-carrier wave, power and bit number for the cognitive user according to the principle that the gain factor gamma mn is larger than the priority or the bit numbers are approximate, newly confirming to-be distributed sub-carrier wave sets SN and UM, newly calculating the interference I generated to the users by the cognitive users, if the I is bigger than the interference threshold value Ith of the authorized users, canceling the sub-carrier wave and the distributing of the power and the bits and finishing the distributing work, if the UM has no to-be distributed cognitive users and the SN still has the to-be distributed sub-carrier wave resources, then distributing the residual carrier waver resources. The method considers the two restraining conditions of the interference threshold and the QoS requirement of the users, thereby further improving the availability ratio of the frequency spectrum and the distributing of the recourses.

The invention provides an in-phase estimation method and a system of the orthogonal frequency division multiplexing (OFDM) technology, wherein the method includes: obtaining the sub-channels which satisfy the given transmission quality in the OFDM symbols; computing the phase offset between the data on the obtained sub-channels and the data on the sub-channels with the same position in the adjacent OFDM symbols; estimating the residual carrier frequency shift and the sampling clock shift of the current OFDM symbols. The method and the system estimates the residual carrier frequency shift and the sampling clock shift through the mutual correlation data on the sub-channels which satisfy the given transmission quality, overcomes the effect of the sub-channel with bad quality to generate the error code, advances the precision of the in-phase estimation to a great extent.

In a communication device, the LO leakage and opposite side band signals are measured at an output signal. Input processing signals to a modulator are adjusted in response to the measured values to minimize the LO leakage and maximize side band suppression.

A nanowire-based device and method employ removal of residual carriers. The nanowire-based device includes a semiconductor nanowire having a semiconductor junction, and a residual carrier sink. The residual carrier sink is located at or adjacent to the semiconductor nanowire near the semiconductor junction and employs one or both of enhanced recombination and direct extraction of the residual carriers. The method includes providing a semiconductor nanowire, forming a semiconductor junction within the semiconductor nanowire, forming a residual carrier sink, and removing residual carriers from the semiconductor junction region using the residual carrier sink.

The embodiments of the invention provide a carrier wave frequency deviation estimation method and system. For the situation of emission of multiple unlinks from different emitters, due to existence of multipath carrier wave frequency deviations, one carrier wave frequency deviation is corresponding to one emitter, and under such a condition, it is quite difficult to estimate and correct the carrier wave frequency deviations at a receiving end easily. The reason is that composite time domain signals of the receiving end form a height nonlinear function about the carrier wave frequency deviations. Therefore, in order to reduce the complexity, by using the method and system provided by the embodiments of the invention, the carrier wave frequency deviations can be corrected before OFDM signals are sent for realizing the purpose that the only deviation needing to be corrected at the receiving end is a common residual carrier wave frequency deviation, such that the receiving end can perform unified common residual carrier wave frequency deviation compensation on the received N OFDM signals. Compared to the prior art, the phenomenon does not exist that channel estimation and carrier wave frequency deviation tracking are always affected by interference between carrier waves.

A method and sytem for achieving carrier frequency synchronization in a high speed receiver. A feedback loop in a carrier recovery system is operated at a down-sampled rate until carrier lock is detected. The output of a phase accumulator, operating at the down-sampled rate, is then extrapolated to provide extrapolated outputs to provide outputs at the original symbol rate. Addresses for a look-up table are then generated from the combined phase accumulator outputs and extrapolated outputs, such that the frequency and phase compensation offsets provided to a phase derotator and slicer are at the original symbol rate. The total pipeline delay as seen by the carrier recovery system is thus reduced. This in turn allows for more efficient correction of residual carrier frequency errors present in a complex baseband signal.

The embodiment of the invention discloses a frequency synchronization method and equipment for an OFDM (Orthogonal Frequency Division Multiplexing) system. In the technical scheme provided by the embodiment of the invention, during frequency synchronization process of the OFDM system, a digital phase-locked loop mechanism is adopted to realize joint estimation of carrier wave frequency deviation and sampling frequency deviation when AD/DA and radio frequency are synchronic, when each frame updates the phase-locked loop state information, only the frequency-domain related characteristics of training symbols are required to be utilized for estimating the residual sampling frequency deviation, and then the residual carrier wave frequency deviation can be obtained through simple calculation, so as to update the frequency deviation estimation. The complexity in system implementation is extremely low, and besides, high estimation precision can be achieved when the digital phase-locked loop is in a locking state.

The invention relates to an MIMO-OFDM system frequency deviation estimation method. The method is used for performing frequency deviation estimation on signals which contain a short training sequence, a long training sequence and an SIG sequence and are received by a plurality of receiving antennas of the receiver of an MIMO-OFDM system. The method of the invention includes the following steps that: coarse frequency deviation is calculated through utilizing the short training sequence of the signals; long training sequence frequency deviation is calculated through utilizing the long training sequence of the signals; time-domain residual carrier frequency deviation is calculated through utilizing the SIG sequence; and the coarse frequency deviation, the long training sequence frequency deviation and the time-domain residual carrier frequency deviation are summated, and a summation result is adopted as the estimation result of carrier frequency deviation. The method has the advantages of high frequency deviation estimation accuracy and wide application range.

An image processing device is provided. The image processing device includes a first shift register connected to a line for reading out an image signal that selects a line where a signal in response to carriers accumulated in an accumulation state for generating carriers in the photo diode in response to received light is read out, regarding each line of the matrix by scanning a plurality of lines in a direction that is perpendicular to each line of a matrix and is designated, a second shift register connected to a line for clearing an image signal that selects a line for clearing an image signal where the residual carriers in the solid-state image-pickup element are discharged from the solid-state image-pickup element, and an output circuit that outputs a reset signal to the first shift register when a direction of scanning lines of the matrix is changed.

A method and apparatus for automated acquisition of a QAM signal. The method employs an embedded state machine progressing from an initial state to a final state. The method comprises the following steps: (A) Performing an automatic gain control (AGC) operation on the incoming QAM signal to maintain a steady amplitude of the QAM signal; (B) Performing a symbol timing recovery of the input QAM signal by adjusting a sampling clock of the symbol timing recovery loop; (C) Performing a Blind Equalization of the QAM signal without carrier lock to minimize a dispersion error of the received QAM signal constellation as compared with an error-free QAM signal constellation by adjusting a set of coefficients of the equalizer; (D) Performing a carrier recovery of the QAM signal to eliminate a residual carrier frequency error and to eliminate a phase error from the acquired QAM signal; and (E) Performing a decision directed equalization (DDE) of the QAM signal by updating a set of coefficients of the equalizer by using a decision based algorithm.

A channel equalizer includes a channel estimator, a coefficient calculator, a multiplier, and an error remover. The channel estimator estimates a channel impulse response (CIR) of input data in which a known data sequence is periodically inserted. The coefficient calculator calculates equalization coefficients using estimated CIR, and the multiplier multiplies the input data with the equalization coefficients for channel equalization. The error removes estimates a residual carrier phase error of the channel-equalized input data and removes the estimated phase error from the input data.

Architecture for processing a record of burst information in a transmission link. A waveform sampler samples a received waveform containing a record of symbols imposed on a carrier signal. Symbol phase of the record symbols is determined utilizing one or more metrics. Any residual carrier error is corrected, and the carrier signal is removed. The phase and time-of-arrival of the burst information associated with a maximum positive correlation value are then determined.

The invention discloses a multi-rate self-adaptive demodulating system aiming at residual carrier modulation. The system mainly aims at a BPSK modulation mode adopting Manchester encoded residual carrier stated in a CCSDS near linkage standard protocol, the information rate can be estimated in the absence of priori information; and the lox-complexity tracking and demodulating can be realized. Through the fine filtering and narrow-band wide-loop tracking, the extracting and tracking on the carrier are realized; the carrier is locked on an I branch and a signal is locked on a Q branch through the tracking of the Costas Loop; the tap extraction on each rate signal is realized; the matching correlation and the energy integral are performed on the Q branch signals on the rate taps according to the characteristics of the Manchester encoding, thereby judging the rate of the current transmission data through the judgment to the energy integral under the condition of unnecessarily knowing the transmission information, and realizing the self-adaptive demodulation.

The invention discloses a non-cooperation BPSK signal decoding method with a polarity judgment operation. The method includes the following steps that (1) a digital medium-frequency channelized receiver detects and receives a BPSK signal; (2) residual carrier frequency of the detected and received BPSK signal is measured roughly; (3) after direct components are filtered out on the basis of square frequency doubling after rough measurement, frequency refining is achieved through CZT frequency measurement, and the residual carrier frequency is calculated; (4) the polarity judgment operation is carried out on the basis that the sequences are combined; (5) code checking is carried out again on the result of the step (4). The method is more suitable for decoding of the BPSK signal in a signal environment with a low signal to noise ratio, the calculation result is more reliable, and calculation complexity is greatly reduced.

An image-processing device is provided. With respect to each line in a matrix, a shift register is installed for reading a line out that selects a line where a signal in response to carriers accumulated in an accumulation state for generating carriers in the photo diode in response to received light is read out. A second shift register is installed that selects a line for clearing an image signal where the residual carriers in the solid-state image-pickup element are discharged from the solid-state image-pickup element. Shift data applied to a line for reading out an image signal is output to the shift register for reading a line out, based on which signal for selecting a line for reading out an image signal is output.