14 results about "Doppler tolerance" patented technology

The invention discloses an OFDM-LFM (Orthogonal Frequency Division Multiplexing-Local Frequency Modulation) integrated signal waveform receiving method and equipment based on fractional Fourier transform, LFM and OFDM are combined and improved, an OFDM-LFM integrated radar communication signal taking an orthogonal LFM signal as a subcarrier is adopted, and as the LFM subcarrier has larger Doppler tolerance, compared with a normal subcarrier, the OFDM-LFM integrated signal waveform receiving method and equipment based on fractional Fourier transform have higher Doppler tolerance, the radar communication signal can be received more accurately. The method not only can improve radar distance resolution and spectral efficiency, but also has a strong capability of avoiding Doppler effect, and can reliably transmit information, and when OFDM-LFM signals are received, in order to solve the problems of subcarrier frequency linear transformation, radar parameter extraction and the like, based on the sensitivity of fractional Fourier transform (FRFT) to LFM signals, the method can be used for solving the problems of subcarrier frequency linear transformation, radar parameter extraction and the like. According to the invention, the FRFT is used as the integrated signal receiver, the separation of the integrated signal communication receiver and the radar receiver is realized, and the system performance is improved while the complexity of the system is reduced.

The invention provides a multifunctional integrated waveform design method based on a multi-sub-pulse structure, and belongs to the field of radar detection communication anti-interference integration. Specifically, an information transmission modulation method based on joint modulation of partial phase modulation in sub-pulses and waveform position arrangement modulation between sub-pulses is proposed, and the communication rate is remarkably improved; intermittent sampling forwarding interference is effectively suppressed by using the orthogonal characteristic of waveforms between sub-pulses. A signal processing method based on monopulse multifunctional integrated echoes is provided, and Doppler tolerance is enhanced; according to the invention, the integration of detection, communication and anti-interference functions is realized, the detection and communication requirements of a high-speed moving target are met, and the engineering application value is high.

This invention discloses a signal Doppler tolerance and sidelobe optimization method based on a weighted ambiguity function template. The method includes determining a discrete ambiguity function based on a two-dimensional ambiguity function of a continuous signal and a radar transmitted signal; obtaining matched filtering results for signals with different Doppler frequency shifts and determining the main lobe and sidelobe positions based on the Doppler frequency shift results; for the Doppler frequency shift case, establishing a cost function for Doppler tolerance optimization and a weighted cost function for joint optimization of Doppler tolerance and sidelobe based on the main lobe and sidelobe positions, respectively; setting the weight coefficients of the weighted cost function according to signal characteristic requirements to obtain the target cost function; and using simulation parameters for iterative updating to obtain the optimization result. This invention can improve signal Doppler tolerance while reducing signal sidelobes, significantly improving the practicality of random noise signals; and it allows for setting weight coefficients according to signal characteristic requirements to adjust the optimization ratio of signal Doppler tolerance and sidelobe, providing strong flexibility.

The invention discloses a detection and communication integrated waveform design method based on multi-sub-pulse time-polar domain joint modulation. The method specifically comprises the following steps: establishing a detection and communication integrated polarization waveform model based on a multi-sub-pulse structure; the time domain and polarization domain combined modulation technology is applied to the detection and communication integrated waveform design of a multi-sub-pulse structure, the communication information is modulated by using waveform time domain and polarization domain resources, and the communication rate is further increased by combining with the existing frequency domain and space domain communication information modulation method; a monopulse detection and communication integrated echo processing method is provided, the high Doppler tolerance of integrated waveforms is ensured, and the detection capability of a high-speed target is improved. According to the method, the communication rate is increased, the Doppler tolerance of the designed waveform is improved, and compared with traditional pulse Doppler radar echo processing, the power at the target is attenuated and slowed down along with the increase of the speed, so that high-speed target detection is facilitated.

The invention discloses a complementary phase coding sequence signal processing method based on distance sidelobe shift and Doppler compensation, and relates to the technical field of radar signal processing, and the method comprises the steps: a radar transmitting signal employs a complementary coding sequence for phase modulation of a signal waveform; aD sampling, digital down-conversion and low-pass filtering are carried out on target echoes received by the radar, then the target echoes are rearranged into an echo signal matrix, and Doppler compensation is carried out on the echo signal matrix; and finally, pulse compression processing and moving target detection are performed on the compensated echo signal, target distance sidelobe moving is realized, and target distance-speed information is obtained. According to the complementary phase coding sequence signal processing method provided by the invention, the target distance sidelobe is effectively suppressed, the Doppler tolerance is improved, and an important technical support is provided for the complementary phase coding sequence signal in the field of low-altitude target detection.

The application provides an m sequence optimization method for a satellite-ground integrated sensing system test, comprising the following steps: step 1, reference sequence performance evaluation: the reference performance comprises a reference peak-to-average power ratio, a reference peak-to-side lobe ratio, a reference integrated side lobe ratio and a reference Doppler tolerance; step 2, comprehensive multi-dimensional cost function construction and mixed optimization strategy: step 201, constructing a comprehensive multi-dimensional cost function capable of weighted adjustment: step 202, defining a normalization function based on the reference performance: step 203, configuring the performance on demand based on the weight coefficient: step 204, minimizing the cost function by using a mixed optimization algorithm; and step 3, generating a final integrated sensing test sequence. The application realizes the collaborative optimization of multiple key performances of communication and sensing for the first time, and can generate a special sequence with excellent comprehensive performance, which can meet the stringent integrated satellite-ground sensing system test requirements.

The present invention relates to a method for improving the Doppler tolerance problem of NLFM signals, and belongs to the technical field of radar signal processing. The method for improving the Doppler tolerance problem of NLFM signals is a solution to the pulse compression performance and main lobe peak delay problems of NLFM signals with Doppler frequency shift. On the one hand, spectrum correction filtering is used to improve the signal pulse compression performance. The spectrum correction filter is designed by making the spectrum correction filter output an ideal window function, thereby significantly suppressing the sidelobe level of the pulse compression result of the NLFM signal with Doppler frequency shift. On the other hand, to address the waveform main lobe peak delay problem caused by Doppler frequency shift, the true peak position of the echo signal is calculated by taking the average of the main lobe peak time of the pulse compression waveform under positive and negative frequency modulation functions, thereby avoiding the influence of Doppler frequency shift on radar ranging.

The application discloses an OFDM-LFM integrated signal waveform receiving method and equipment based on fractional Fourier transform, which combines and improves LFM and OFDM, adopts OFDM-LFM integrated radar communication signals taking orthogonal LFM signals as subcarriers, and has the advantages that, due to the large Doppler tolerance of the LFM subcarriers, compared with sinusoidal subcarriers, the method can not only improve radar range resolution and spectral efficiency, but also has strong ability to avoid Doppler effect, and can reliably transmit information; when receiving OFDM-LFM signals, in order to solve subcarrier frequency linear transformation and radar parameter extraction and other problems, based on the sensitivity of a fractional Fourier transform (FRFT) to LFM signals, the application uses the FRFT as an integrated signal receiver, realizes separation of an integrated signal communication receiver and a radar receiver, reduces the complexity of the system, and improves the system performance.

A frequency-shift symmetric chirp spread spectrum modulation and demodulation method for interstellar communication links. The transmission process includes several steps: serial-to-parallel conversion, index addition, Gray coding, binary-to-decimal conversion, and frequency-shift symmetric chirp spread spectrum modulation. On the other hand, the reception process comprises demodulation of the symmetric chirp signal, fast Fourier transform, peak retrieval, decimal-to-binary conversion, Gray decoding, index removal, and parallel-to-serial conversion. The frame structure includes a preamble code, synchronization word, and user data. The symmetric chirp signal includes a pair of chirp signals with opposite polarities, ensuring the continuity of phase and frequency during the signal concatenation process. Compared to traditional chirp signals, the symmetric chirp signal exhibits superior correlation characteristics, enhanced noise resistance, and improved Doppler tolerance, making it particularly suitable for interstellar communication links.

The application belongs to the technical field of synchronous signal capture, and discloses a kind of underwater acoustic PN signal time domain coarse capture method and system based on deep learning, adopt receiving end local carrier compression algorithm to convert PN correlation gain amplitude frequency deviation response into the approximate flat of multiple SINC function module non-coherent accumulation, based on the circular convolution of local carrier compression time domain parallel correlation result output is used for TCN-Seq2Seq model provides the correlation waveform feature of large doppler tolerance;Utilize TCN-Seq2Seq model to realize the time domain synchronization of low signal-to-noise ratio condition based on the circular correlation output waveform of carrier compression, identify and analyze the received waveform, output waveform time domain range, obtain the coarse estimation of Doppler frequency deviation, complete time domain frequency domain coarse capture.The application greatly reduces the computing overhead, and has high value for the application of underwater acoustic communication of PN signal in military and biological friendly direction.

The invention provides a through-the-wall radar clutter suppression method based on spatial frequency diversity, and aims to solve the problems of background clutter interference and difficulty in low-speed moving target detection of a through-the-wall radar in a complex indoor environment. The method mainly comprises the following steps: solving a problem P1 (formula (1) in the specification), and generating a signal waveform with low sidelobe and good Doppler tolerance through multiband radar signal waveform optimization design; solving a problem P2 (formula (2) in the specification), and optimizing a beam array according to antenna directional diagrams of different frequency signals in combination with an antenna beam forming technology; according to multi-band radar array signal processing based on bat bionics, effective distinguishing of target signals and background clutters is achieved by comparing echo power ratios of different frequency signals in different directions.

The invention relates to an adaptive pulse compression method of a convolutional neural network. The method comprises the following steps: constructing a pulse compression network consisting of a plurality of cascaded sub-networks; wherein each sub-network comprises a Doppler compensation branch and a power estimation branch which are arranged in parallel, feature fusion is realized through cross-level residual connection, and output ends of the Doppler compensation branch and the power estimation branch are respectively connected with a CNN-based pulse compression branch; doppler tolerance and array element error compensation priori knowledge are embedded into network weight through offline training, so that the network has robustness for unmodeled distortion; and receiving a radar transmitting signal and a radar echo signal, performing end-to-end forward propagation by using the pulse compression network, and synchronously outputting an adaptive pulse compression result after sidelobe suppression and Doppler offset compensation. Compared with the prior art, the comprehensive performance bottlenecks of the existing adaptive pulse compression method in the aspects of calculation complexity, Doppler compensation robustness, complex scene adaptability and non-ideal factor fault tolerance are overcome.

The invention provides an m sequence optimization method for satellite-to-ground sensing integrated system testing. The m sequence optimization method comprises the steps that 1, reference sequence performance evaluation is carried out, wherein reference performance comprises a reference peak-to-average power ratio, a reference peak value sidelobe ratio, a reference integral sidelobe ratio and reference Doppler tolerance; step 2, constructing a comprehensive multi-dimensional cost function and a hybrid optimization strategy: step 201, constructing the comprehensive multi-dimensional cost function capable of performing weighted adjustment; step 202, defining a normalization function based on reference performance; step 203, performing performance on-demand configuration based on a weight coefficient; step 204, performing cost function minimization by adopting a hybrid optimization algorithm; and step 3, generating a final sensing integration test sequence. According to the method, collaborative optimization of multiple key performances of communication and perception is realized for the first time, and a special sequence which is excellent in comprehensive performance and can meet the test requirements of a strict satellite-ground communication and sensing integrated system can be generated.

The present invention discloses a radar communication integrated waveform design method of NC-CE-OFDM, including: setting signal parameters and initializing the target state; determining the subcarrier position and PAPR of the unoccupied frequency band through dynamic spectrum sensing and channel estimation technology; using phase technology to reduce PAPR, and modulating communication information on the subcarrier of the unoccupied bandwidth for transmission; solving the bit error rate of the non-continuous constant envelope integrated signal in the additive white Gaussian noise channel; solving the fuzzy function in the radar communication integrated signal; solving the distance resolution, Doppler resolution and Doppler tolerance characteristics of the integrated signal waveform according to the fuzzy function. The present invention combines non-continuous OFDM signals with phase modulation technology, which can alleviate the problem of tight spectrum resources and achieve the maximum utilization of the spectrum of non-continuous OFDM signals.