5results about How to "Improve capture speed" patented technology

The application belongs to the field of communication measurement and control, and particularly relates to a measurement and control transponder system and equipment for quickly and reliably capturing a mixed spread spectrum signal, and aims to solve the problem of insufficient system precision and weak reliability. The application comprises a digital down-conversion module for receiving a signal and performing digital down-conversion processing on the signal; a direct spread code capture module for capturing the zero intermediate frequency signal and performing modulation to obtain a spread spectrum signal; a frequency hopping interval division module for dividing the bandwidth of the spread spectrum signal into N parallel frequency hopping intervals according to a frequency hopping pattern; a matched filter module for filtering the signal and performing N-point Fourier operation; a capture decision module for comparing the code phase with a threshold value, and if the threshold value is exceeded, determining that capture is successful; and a synchronization refresh module for performing dynamic refresh through a synchronization refresh algorithm. The application improves the capture speed and reliability of the measurement and control transponder.

The invention discloses a high-sensitivity rapid acquisition method and system used in a satellite-ground dynamic environment, and the method comprises the steps: S1, transmitting a communication signal which accords with a target communication frequency through a transmitting end, and receiving the communication signal through a receiving end; s2, a plurality of local signals with different frequency points are generated in a frequency search interval through a local parallel digital control oscillator NCO group, and FFT-IFFT capture judgment is carried out on communication signals; s3, if it is judged that capturing fails, the frequency search interval is adjusted, and the step S2 is executed again; if it is judged that capture fails in the two adjacent frequency search intervals, performing sideband interval estimation on the two adjacent frequency search intervals, and performing FFT-IFFT capture judgment according to a sideband interval estimation result; and repeating the steps until the capture is determined to be successful. Under the conditions that the detection probability exceeds 99%, the minimum carrier-to-noise ratio is 34.66 dB and the minimum signal-to-noise ratio is 16 dB, the receiver sensitivity of-130 dBm can be achieved, the total Doppler frequency offset capture range can reach 140 kHz, and the capture time can be as low as 0.8 second.

The invention provides a coarse and fine switching method and device in satellite top-crossing tracking and pointing, and the method comprises the steps: carrying out the state estimation and uncertainty quantification based on the instantaneous pointing error of a satellite top-crossing tracking and pointing system at a satellite top-crossing stage, generating and dynamically updating the two-dimensional probability density distribution describing the position of a light spot, and carrying out the dynamic updating of the two-dimensional probability density distribution; fusing with a light intensity distribution diagram influenced by atmospheric turbulence to obtain an effective receiving index, and determining a region of interest for fine aiming detection from probability distribution; performing spatio-temporal clustering analysis on multiple frames of detection data continuously collected by the fine aiming equipment, and calculating the coordinates of a fine aiming tracking point and the identification confidence of the fine aiming tracking point; and predicting the tracking interruption probability based on the atmospheric turbulence prediction data and the probability distribution, performing judgment in combination with the confidence coefficient, and if the judgment is passed, switching the control system to a fine aiming closed-loop tracking mode. According to the invention, rapid, reliable and anti-interference automatic switching from coarse aiming to fine aiming can be realized in a high dynamic scene in which a satellite rapidly passes through the top, so that rapid establishment and stable maintenance of a free space optical communication link are ensured.

The invention discloses a method and a system for quickly capturing a low-orbit high-dynamic signal, which relate to satellite communication and signal processing technologies, and comprise a time-sharing parallel correlation step: receiving an intermediate frequency signal, searching a code phase by performing correlation operation on a local pseudo code and the intermediate frequency signal, and after each correlation operation, performing time-sharing parallel correlation on the local pseudo code and the intermediate frequency signal; enabling the local binary phase shift keying (BPSK) modulation pseudo code to slide on a code phase by a stepping amount corresponding to the number of parallel correlators so as to finish coarse capture of the code phase; a frequency secondary search step: applying a plurality of different Doppler frequency compensation values to the intermediate frequency signal in sequence according to the code phase coarsely captured by the code phase, and repeating correlation operation after each compensation; and determining the Doppler frequency compensation value corresponding to the generated maximum correlation peak value as the optimal Doppler frequency estimation value. According to the method, the problem of discontinuous MCSK signal code phases in the capturing process is solved, and the signal capturing speed is greatly increased.

The invention discloses a high-dynamic scene new system Beidou signal rapid capture IP circuit design based on an FPGA, and the design comprises a single-channel PMF-FFT capture algorithm module, a capture judgment logic module, and a high-dynamic B1C signal parallel capture IP circuit design. The single-channel PMF-FFT capture algorithm module comprises a short-time matched filter operation module, an FFT state control module, an FFTIP operation module and a coherent integration module, and the capture judgment logic module comprises a capture judgment threshold generation module, a peak value detection module and comparison logic. The advantages are realized by adopting the FPGA chip: algorithm upgrading is facilitated, parallel design can be realized, and the capture speed is improved; the data utilization rate is increased; the improved matched filter coefficient is convenient for FPGA internal implementation, and B1C signal capture can be carried out; the PMF-FFT capture algorithm meets the capture bandwidth in a high dynamic environment; incoherent integration and noise estimation design: increasing the gain of the incoherent integration; and line processing: the capture time and the data utilization efficiency are improved.