202 results about "Symbol rate" patented technology

The invention discloses a time synchronization method suitable for a satellite communication system, and the method comprises the steps: analyzing a forward broadcast signal, and obtaining the reference time of a network clock; constructing a geometric prediction handle based on satellite orbit data, and predicting one-way propagation time delay between a terminal and a satellite by using the geometric prediction handle; estimating the processing delay of the terminal according to the symbol rate and the equipment working condition of the terminal and the delay calibration data; fusing the network clock reference time with the processing delay estimate to synthesize a terminal local time; and the sending time of the return link is calculated based on the local time and the propagation delay prediction. According to the method, the synchronization precision can be improved to a microsecond level, the convergence speed in a dynamic scene is accelerated, adaptive compression of the guard interval is supported, and the stability and spectrum efficiency of a satellite communication system are effectively improved.

An apparatus and a method for recovering clock and data from a multilevel pulse amplitude modulated signal received as input signal is suggested. The apparatus comprises a phase detector, a low-pass filter, a voltage-controlled oscillator, and a feedback loop forming a CDR loop. The voltage-controlled oscillator outputs a clock signal that is provided to the phase detector. The phase detector receives an MSB signal from a sampler. The apparatus also comprises an interleave circuit configured to receive the input signal and to generate two output signals having a smaller symbol rate than the input signal. The apparatus further comprises a logical gate configured to receive the output signals from the interleave circuit and to generate an enable signal for the phase detector indicating symmetrical transitions in the input signal. Lastly, the apparatus comprises a converter converting the output signals from the interleave circuit into an MSB and an LSB bit stream.

A frequency offset estimation method for a satellite VDES system, characterized in that it includes the following steps: step 1, down-converting a carrier-containing signal output by an AD to move the signal to a baseband; step 2, performing CIC down-sampling processing on the down-converted signal to reduce the data rate to 4 times the symbol rate; step 3: performing frame synchronization processing on the CIC down-sampled signal to find the position of the frame header; step 4: performing coarse frequency offset estimation and compensation on the signal after the frame synchronization processing; step 5: performing Mpart fine frequency offset estimation on the signal after the coarse frequency offset compensation.

The invention proposes a transmitter arranged to transmit a sequence of physical layer frames at a physical layer symbol rate, said sequence being filtered with a transmit filter, and comprising adaptive coding and modulation means arranged to determine a modulation and coding for transmitting data, whereby the transmitter maps the data in frames using said modulation and coding and inserts encoded and modulated data frames into the sequence. The transmitter further inserts prior to said filtering with the transmit filter, fill frames modulated (and encoded) with a first fill modulation (and coding), said first fill modulation (and coding) selected from a set of fill modulations (and codings) comprising at least one fill modulation (and coding) with a modulation order higher than QPSK.

The invention relates to the technical field of satellite communication, and discloses a residual frequency offset compensation method, device and equipment, a storage medium and a computer program product, and the method comprises the steps: determining a linear interpolation phase step length according to frame header information in a data frame; calculating a phase offset estimation value and a phase change parameter based on the linear interpolation phase step length and interval data between any two pilots in the data frame; and when it is detected that the phase shift estimation value has a phase cross period, compensating the phase shift estimation value according to the phase change parameter to obtain modulation data phase information. Large residual frequency offset estimation and residual phase linear interpolation compensation can be carried out in each frame, the complexity of carrier fine synchronization and phase recovery is reduced, and the system phase recovery time under the condition of low symbol rate is greatly shortened.

The invention discloses an FPGA (Field Programmable Gate Array) implementation method of a DVB (Digital Video Broadcasting) high-speed demodulator. A digital signal enters a parallel DDC (Direct Digital Control) module and is re-adapted to multiple symbol rates; the parallel AGC module adjusts the power of the digital signal to a fixed power value; the method comprises the following steps: passing through Oamp; m algorithm: completing symbol synchronization; related peaks are extracted, and frame synchronization is completed; correcting the frequency to enable the frequency to reach participation frequency deviation; performing frequency compensation on the digital signal after loop filtering; after error information is calculated and filtered, the digital signal is compensated; and restoring the original information of the digital signal. According to the invention, by adopting the parallel processing module, the real-time performance and the parallelism degree of digital signal processing can be greatly improved, and the performance of the whole demodulator is enhanced. Each module is designed to be adaptive to the change of a digital signal, for example, the AGC module can dynamically adjust the power of the digital signal to ensure that the output digital signal is always kept at a fixed power level so as to adapt to different receiving conditions.

The invention belongs to the technical field of signal processing, and particularly relates to a coherent light high-speed transmission signal processing method based on deep joint compensation, which comprises the following steps of: performing fine frequency offset and inter-carrier interference joint preprocessing on a coherent light receiving sampling sequence; obtaining a pre-processing output sequence and at least one estimation parameter derived from fine frequency offset and inter-carrier interference combined pre-processing; inputting the preprocessing output sequence into a diffusion type score guide joint compensation network module to obtain a deep joint compensation sequence; performing online judgment and decoding on the deep joint compensation sequence, and adaptively updating internal parameters of the diffusion type score guide joint compensation network module when a preset adaptive updating condition is met; according to the invention, the symbol residual error can be obviously reduced, the forward error correction gain can be improved, and the stability and robustness of the system under high-order modulation, high symbol rate and long-distance link scenes can be enhanced.

The invention discloses a time interval error jitter extraction method based on Hilbert transform, and relates to the field of high-speed data signal processing, and the method comprises the steps: firstly carrying out the statistics through a level histogram after a detected data signal is obtained, and determining a corresponding level judgment reference; secondly, performing Hilbert transform on the tested data signal to obtain time information of a jump edge of the tested data signal; an accurate code element rate of a measured data signal is extracted by adopting a coarse frequency estimation and fine frequency estimation method, and high-precision constant frequency clock recovery is carried out; according to the Hilbert transform-based time interval error jitter extraction method provided by the invention, a basis is provided for high-precision time interval error jitter, and jitter measurement is accurately carried out on a measured data signal.

A test and measurement device has an input port to receive a signal from a device under test (DUT), the signal having a symbol rate, one or more analog-to-digital converters (ADC) to convert the signal to waveform samples at a sampling rate, and one or more processors, when aliasing is present: up-sample a portion of the signal having aliased samples to produce up-sampled samples; use the up-sampled samples to produce a real-time waveform; perform clock recovery on the real-time waveform to produce a recovered clock; and resample the aliased samples to produce a non-aliased waveform.

The invention relates to the technical field of satellite communication, and discloses a method, equipment and a program product for determining the influence of residual frequency offset on packet error rate performance, which are applied to an SC-FDMA communication system with channel coding, and the method comprises the following steps: under the condition of no frequency offset and different signal-to-noise ratio conditions, carrying out analogue simulation to obtain system packet error rates under different constellation mapping; under the condition of no frequency offset and the same signal-to-noise ratio, calculating a first symbol error rate of the system under different constellation mappings; under the condition of different residual frequency offsets, calculating a second symbol error rate of the system under different constellation mappings; according to a comparison result of the first symbol error rate and the second symbol error rate, calculating a noise variance required for reaching the system packet error rate when the residual frequency offset exists; and determining a prediction result of the residual frequency offset on system performance reduction according to the noise variance. Therefore, by combining theoretical calculation with simulation means, the influence of the residual frequency offset on the system performance can be accurately predicted, the system design is optimized, and the communication quality and reliability are improved.

A communication system includes a transmitter and one or more receivers. The transmitter is arranged to transmit a sequence of physical layer frames at a physical layer symbol rate. An adaptive coding and modulation optimization means are arranged to determine a first modulation and coding for transmitting per receiver of one or more receivers. The transmitter further inserts fill frames modulated (with a first fill modulation) prior to filtering with the transmit filter. The first fill modulation is selected from a set of fill modulations with at least one modulation with a modulation order higher than QPSK. The communication system includes link quality detection, which means to determine a metric of the communication link quality from a version of physical layer frames at the receive side. The physical layer frames include the fill frames and convey the link quality metric to the adaptive optimization means.

The invention provides a signal transmission method and device, and the method comprises the steps: receiving first information, the first information is used for indicating a first index corresponding to a first signal, the first signal is borne in a single carrier for transmission, the first index is used for indicating a first parameter group in a first incidence relation, and the first parameter group is used for indicating a second parameter group in a second incidence relation; the first association relationship comprises a plurality of indexes and a plurality of parameter groups corresponding to the plurality of indexes respectively, the first parameter group is a parameter group associated with the first index, the parameter group comprises a sampling frequency and / or a symbol rate, the sampling frequency is equal to a sampling frequency corresponding to a subcarrier interval of multiple carriers, and the symbol rate is equal to the sampling frequency corresponding to a subcarrier interval of the multiple carriers. The symbol period determined based on the symbol rate is equal to the symbol period of one subcarrier interval of the multicarrier, and transmitting the first signal according to the first parameter group, so that the communication device can transmit and receive a single-carrier signal and a multicarrier signal through the same set of parameters, thereby reducing the implementation complexity and saving the cost.

A transmitter at a first location transmits the message at a symbol rate of the reference clock using a first carrier, whose phase is locked to a phase of the reference clock and whose frequency is a first integer times a frequency of the reference clock. It also transmits the message at the symbol rate of the reference clock using a second carrier, whose phase is locked to the phase of the reference clock and whose frequency is a second integer times the frequency of the reference clock. The second integer is unequal to the first integer. A receiver at a second location receives the message at the first carrier and at the second carrier, and accurately determines a time of a first phase difference between the first carrier and the second carrier. It determines a time of receiving the message from the time of the first phase difference.

The invention belongs to the technical field of high-speed serial link data jitter extraction, and particularly discloses a high-speed serial link jitter extraction method based on a cyclostationary characteristic, which comprises the following steps of: determining a turning point of an initial code element by adopting a self-adaptive algorithm; segmenting the data according to a sampling multiple N, and calculating a cyclic autocorrelation function at a code element rate; obtaining the phase of the cyclic autocorrelation function, wherein the phase comprises the jitter information of each code element; the phase is fitted by using a least square method, accumulated jitter errors generated by inherent phase shifts such as channels are removed, accurate jitter information of each code element of the high-speed serial link is obtained, and the method has the advantages of being simple to implement and low in calculation complexity.

The invention provides a communication radiation source individual identification method based on time domain and time sequence coding constellation diagram feature fusion. The method is used for realizing stable identification of different transmitters under non-ideal conditions of carrier frequency offset, noise interference and the like. The method comprises the following steps: firstly, carrying out normalization and fixed-length interception on a received I / Q signal, and calculating an oversampling multiple according to a symbol rate and a time resolution; then, a time domain and time sequence coding constellation diagram double-branch feature extraction network is constructed, a time domain structure feature is extracted from a time domain branch by adopting a one-dimensional modified ResNet18, and a constellation diagram with time information is generated from a time sequence coding constellation diagram branch through a time sequence coding constellation module and the feature that the phase changes along with time is extracted; and carrying out joint modeling on the two types of features through a trainable weighted fusion mechanism. In the training stage, the performance of the model is improved by adopting cross entropy loss, an Adam optimizer, learning rate scheduling and an early stop strategy. In the reasoning process, input signals are classified by using the model weight with the highest verification accuracy, and a communication radiation source individual identification result is output. Experimental results show that the method can effectively enhance the frequency offset robustness and generalization ability of the model, realizes high-precision identification of the individual communication radiation source, and is suitable for the fields of security access of the Internet of Things, spectrum monitoring, electronic countermeasures and the like.

The invention discloses a short-wave 2FSK signal symbol synchronization system and method in the technical field of signal burst detection, and the method comprises the steps: carrying out the signal energy detection of a short-wave 2FSK signal, and judging whether a signal burst exists or not; in response to existence of the signal burst, performing synchronization signal burst initial indexing; after a signal burst start index is synchronized, cumulative sum calculation is carried out on signal start part data in a single stepping mode, and a burst start position is determined; performing cross-correlation calculation on the burst through the feature sequence from the initial position of the burst, and determining a position index of a frame header; calculating the length of each frame based on the position index of the frame header; calculating an actual symbol rate based on the length of each frame in combination with a theoretical symbol rate; and carrying out symbol synchronization through the actual symbol rate. According to the method, the synchronization accuracy is improved, synchronization is carried out by calculating the accurate symbol rate, and subsequent code word judgment is facilitated.

The present invention relates to a transmission system (1) for generating a signal to be transmitted via one or more physical carriers to a plurality of earth station receivers of a satellite communication system. The transmission system comprises - encoding means (10) arranged to convert per physical carrier a single stream of baseband frames each associated to a modulation and coding, modcod, into a single stream of XFEC frames according to the DVB-S2X standard, - framing means (20) arranged to convert per physical carrier the single stream of XFEC frames to a single stream of IQ symbols comprising one or more superframes according to the DVB-S2X standard, each superframe comprising at least a superframe preamble, - modulation means (30) arranged to convert per physical carrier the single stream of IQ symbols at a physical carrier symbol rate into IQ samples. The transmission system further comprises a superframe placer (5) to attach to the single stream of baseband frames or the single stream of XFEC frames metadata indicating to the framing means when a superframe preamble needs to be inserted in the stream of IQ symbols composed in the framing means.

The invention relates to the technical field of signal analysis and processing, in particular to an FSK signal blind demodulation method and system in underwater acoustic communication signal analysis and processing, and the method comprises the steps: carrying out the coarse estimation of the bandwidth and carrier frequency of an underwater acoustic FSK signal; performing symbol rate estimation and timing synchronization based on an enhanced digital phase-locked loop; down-converting the received signal to zero intermediate frequency; carrying out discrete short-time Fourier transform to obtain a time-frequency domain distribution matrix of the signal; extracting time-frequency domain distribution in a time dimension by taking a symbol period as an interval, and taking out a frequency point with the strongest power at a corresponding moment to obtain a time-frequency distribution sequence of the signal; clustering the time-frequency distribution sequence by using K-means clustering, and judging the modulation order M of the FSK signal according to the contour value; and clustering the time-frequency distribution sequences into M classes, simultaneously obtaining the class to which the frequency corresponding to each sampling point in the sequences belongs, and judging the class as an M-system symbol until the blind demodulation is finished. According to the invention, blind demodulation of FSK signals with guard intervals and without guard intervals can be realized.

The invention discloses a resource allocation method and device, equipment, a storage medium and a product, and relates to the technical field of communication, and the method comprises the steps: obtaining a symbol rate and a historical demand bandwidth supported by a satellite terminal in response to a received login request of the satellite terminal; selecting or determining a candidate sub-band set from pre-divided sub-bands based on the symbol rate supported by the satellite terminal and the historical required bandwidth; respectively calculating discreteness indexes of corresponding spectrum utilization rates when the satellite terminal accesses each sub-band in the candidate sub-band set; and selecting or determining a target sub-band from the candidate sub-band set based on the discreteness index of the spectrum utilization rate, and allocating the target sub-band to the satellite terminal. According to the invention, the sub-band optimization is carried out according to the discreteness index of the corresponding spectrum utilization rate when the satellite terminal accesses each available sub-band, and the balanced distribution of base station resources is realized, so that the spectrum utilization rate of the base station is improved, the burden of the base station is reduced, and the use cost is reduced.

The invention provides a communication perception fusion waveform design method based on space-time constructive interference, which belongs to the field of wireless communication and comprises the following steps: establishing a downlink multi-user communication perception fusion system model; establishing a communication model and a sensing model; establishing an optimization problem for minimizing the transmitting power, wherein the optimization problem has a space-time constructive interference constraint condition and a CRB constraint; after the CRB constraint of the optimization problem is relaxed into linear constraint by using a continuous convex approximation technology, a second optimization problem is obtained through iterative solution, the second optimization problem is simplified through a Lagrangian multiplier method and a Carush-Kuhn-Tuck condition, and the simplified second optimization problem is solved through iterative solution of a main optimal minimization algorithm; and obtaining a designed transmitted waveform vector. According to the invention, the symbol error rate of transmission and the transmitting power of the transmitting end can be effectively reduced under the condition that the communication and sensing performance requirements are met.

This invention discloses a radar embedded communication method based on OTFS modulation. The implementation steps are: 1. Generating an integrated signal based on OTFS modulation; 2. Estimating the relative speed and distance of the RF tag by the integrated signal receiver; 3. Modeling the time-domain channel based on the speed and distance measurement results of the RF tag by the integrated signal receiver; 4. Equalizing the received signal using the constructed time-domain channel matrix and performing decorrelation decision on the equalized signal. This invention utilizes the characteristic that OTFS signals can obtain full channel diversity in both time and frequency, achieving a more accurate estimate of the time-varying frequency-selective bidispersive wireless channel, and equalizing the fading signal, reducing the communication symbol error rate and effectively improving the communication reliability of the radar embedded communication system.

The invention relates to the technical field of signal processing, in particular to a joint estimation method and system for time domain parameters of multiple time-frequency overlapped signals, and the method comprises the steps: obtaining a generalized cyclic correlation entropy spectrum of the multiple time-frequency overlapped signals, reconstructing the generalized cyclic correlation entropy spectrum through a compressed sampling matching pursuit algorithm, removing redundant information, and improving the definition and resolution of the spectrum; the speed and precision of spectrum peak searching are improved through an improved grey wolf optimization algorithm, spectrum peak searching is carried out on generalized cyclic correlation entropy spectrum projection, and therefore joint estimation of the carrier frequency and the code element rate is achieved. According to the method, joint estimation and correction of the Cramer-Rao bound in the alpha stable distribution noise environment is deduced, and the method is used for evaluating the effectiveness of the method. When the method is used for reconstructing the entropy spectrum, the influence of impulse noise can be suppressed, so that the reconstructed entropy spectrum is sharper and more gathered; the method has low calculation complexity and higher estimation precision, is suitable for efficient joint estimation of multi-signal time domain parameters, and meets the multi-signal processing requirement in a complex environment.

The invention discloses a variable rate signal generation method suitable for a satellite communication system, which comprises the following steps: receiving a system master clock, and generating a frequency division signal; performing modulation data generation based on the divided signal and the predictive data request signal; carrying out interpolation and pulse shaping on the modulation data, and carrying out adaptive sampling rate multiplication processing; continuous accurate speed conversion of the phase is realized through a phase perception interpolation function; and optimizing cache resource allocation by using a Markov decision process. According to the method, the variable symbol rate signal is generated under the condition of a fixed D / A sampling rate, the key problems of spectrum fidelity, phase continuity, cache optimization, load prediction and the like are solved, and the resource utilization efficiency and the service quality of a satellite communication system are improved.

The invention provides a fast differential frame synchronization method under a burst transmission system, which comprises the following steps: a receiver reduces the sampling rate of a burst transmission sequence to four times of a symbol rate, detects the timing error of a down-sampling sequence, calculates an integer parameter and a fraction parameter based on a timing error result, and performs frame synchronization according to the integer parameter and the fraction parameter; then, a cubic interpolation filter is used for calibrating timing errors and recovering a correct data sequence, a differential frame synchronization method which is insensitive to signal amplitude and suitable for any phase deviation is used for searching a frame header position, and whether the size of a correlation peak value is larger than a set threshold value or not is judged; if yes, timing synchronization and frame synchronization are completed; and if not, returning to continue to calculate the timing error. The method is suitable for a burst transmission system, is different from a traditional frame synchronization method, does not need to carry out frequency difference estimation, amplitude control and carrier synchronization in advance, and can quickly realize timing synchronization and frame synchronization, so that the synchronization time is shortened.

The invention provides a frame header synchronization method based on a CPM constant envelope spread spectrum sequence, and belongs to the technical field of satellite-borne satellite communication. A traditional recursive feedback type structure based on a phase-locked loop (PLL) is optimized, and a matched filter, a resampling module and a delay locked tracking loop (DLL) module are added after frame header pulse detection and frequency offset estimation are completed by utilizing the differential self-correlation characteristic of a synchronous sequence. The single symbol rate timing error estimation result serves as negative feedback and is fed back to the matched filter for resampling operation, the optimal resampling point is continuously adjusted, the symbol synchronization establishment time is greatly shortened, and then frame header synchronization of LINK20 received signals is achieved. The method has the advantages of being easy to implement, low in complexity and high in real-time performance and synchronization precision.

The invention provides a PSK (Phase Shift Keying) signal symbol rate blind estimation method based on an envelope spectrum, a medium and a device. The method comprises the following steps: step 1, carrying out bandwidth coarse estimation on a received signal; 2, based on a bandwidth coarse estimation result, filtering is carried out, and then an envelope spectrum narrowband peak-to-average ratio is calculated in a sliding mode; 3, based on the envelope spectrum narrow-band peak-to-average ratio, calculating a peak-to-average ratio mean value corresponding to the peak index, and determining a peak-to-average ratio mean value maximum index; and step 4, based on the peak-to-average ratio mean value maximum index, finishing symbol rate precise estimation by using a parabola fitting method. The method can effectively solve the problems that a traditional method is insufficient in performance under the low signal-to-noise ratio, and estimation precision depends on a large number of signal samples.

The invention discloses an anti-high dynamic Doppler low signal-to-noise ratio satellite signal blind detection method, which comprises the following steps of: performing frequency domain analysis on a delay correlation signal according to a signal symbol rate, and dividing a signal band and a noise band near the delay correlation signal to construct a detection quantity to perform constant false alarm rate (CFAR) detection; and finally, obtaining a final signal existence or disappearance result through time consistency judgment. According to the method disclosed by the invention, the analytic CFAR threshold and the state machine smoothing are combined, and the problem of detection failure in a low signal-to-noise ratio and high dynamic Doppler environment in the prior art is solved.

The invention discloses an encryption burst communication receiving method based on an FPGA, and belongs to the technical field of burst communication. According to the invention, the problems of poor synchronization performance and poor anti-interference capability at the receiving end in the existing method are solved. According to the method, the carrier synchronization range is expanded by introducing the pilot frequency to enable the synchronization heads to be '1', the limitation that a conventional frequency offset estimation algorithm can only work under the condition that the Doppler frequency shift is smaller than 0.5 times of the symbol rate is broken through, and the capacity of the system for adapting to the high-dynamic environment is improved. A spreading code continuous tracking working mode is designed, coarse estimation and synchronization are carried out in a frame header part, spreading codes are still adopted in an information part, and continuous tracking is carried out, so that the system can adjust the phase of the spreading codes in real time in the whole frame to solve the problem of phase error accumulation caused by adopting a low-precision clock; the problems that when one frame of data at the sending end is long, the synchronization performance is reduced when a low-precision clock is adopted, and even effective synchronization cannot be achieved are solved. The method can be applied to the field of burst communication.

Methods, systems, and devices for a wakeup receiver operation is described. A receiver may include a conversion circuit that converts an RF signal to a baseband signal, where the baseband signal comprise a set of symbols received at a symbol rate. The receiver may include an analog-to-digital converter that converts the baseband signal to samples at a sample rate greater than the symbol rate. The receiver may include a set of correlators, each correlator of the set may receive a respective subset of the samples of the baseband signal and generate a respective output. The receiver may include a compare circuit that receives the respective outputs from the set of correlators and compares the respective outputs with a threshold, where the compare circuit also generates a wakeup command based at least in part on at least one output of the respective outputs satisfying the threshold.

The invention discloses a front-feedback combined burst signal fast symbol synchronization method, which relates to the technical field of digital signal processing and satellite communication, and comprises the following steps: firstly, sampling a received signal subjected to matched filtering processing according to a 4-time symbol rate by using an initial NCO (Network Controlled Oscillator), then dividing a sampling value into two paths, sending one path to an FIFO (First In First Out) register for caching, and using Oamp in the other path; the method comprises the following steps of: firstly, performing timing deviation estimation by using an FIFO (First In First Out) register and an M algorithm, secondly, determining a moment when the FIFO register starts to read data, an oscillation initial value of an interpolation control NCO and an initial value of an interpolation coefficient according to a timing deviation estimation result, starting the interpolation control NCO, and then, sending the data read by the FIFO register into a Farrow structure interpolation filter for interpolation processing according to the initial value of the interpolation coefficient. And finally, a Gardner loop is started, feedback control is carried out on the interpolation control NCO, and an interpolation result is output, so that the fast symbol synchronization speed and precision of the burst signal are improved, and the stability and timeliness of fast symbol synchronization of the burst signal are guaranteed.