38 results about "Doppler bandwidth" patented technology

The invention discloses a method and device for determining the effective Doppler bandwidth of a fuze receiver. The method comprises the steps of dividing a target into multiple target scattering surface elements after geometric modeling is conducted on the target, calculating the Doppler shift of each target scattering surface element and the echo power generated by each target scattering surface element under the missile target encounter condition, drawing a Doppler frequency spectrum diagram of the target according to the calculated Doppler shift and echo power of each target scattering surface element, and cutting out a spectral line range within which echo power is larger than set threshold power from the drawn Doppler frequency spectrum diagram and determining the effective Doppler bandwidth of the fuze receiver according to the cut-out spectral line range. By the adoption of the method and device, estimation of the effective Doppler bandwidth of the fuze receiver can be achieved, so that the fuze receiver can be designed based on the estimated effective Doppler bandwidth of the fuze receiver during fuze slideway testing, and then fuze slideway testing is facilitated.

The invention provides an SAR motion target detection method based on Doppler spectral analyses. The SAR motion target detection method based on Doppler spectral analyses is used for detecting ground motion targets in an SAR picture, and mainly solves the problem that an existing detection method is not high in detection probability so as to improve detection probability. According to the method, rectangular neighborhoods of scattering points in the SAR picture are chosen, clutter lock is conducted on Doppler frequency spectrums in each neighborhood to acquire Doppler center frequency, and then standard deviations of frequency spectrums after clutter lock are calculated to represent Doppler bandwidths. Traversal is conducted on all scattering points in the SAR picture, the scattering points are processed in the same way, statistics is then carried out, a measure is constructed through obtained statistics to ensure that the detection boundary of the measure is an oval, and a detection threshold is determined according to constant false alarm rate (CFAR). Because the detection boundary is an oval, on the premise that the constant false alarm rates are the same, oval detection boundary detection probability is larger than rectangle detection boundary detection probability, and target missing detection does not occur easily.

The invention provides a phase-locked loop circuit for implementing weak carrier signal acquisition. The phase-locked loop circuit comprises a first phase discriminator, a loop filter, a voltage-controlled oscillator (VCO), an adder and a scanning voltage generation circuit, wherein the first phase discriminator, the loop filter, the adder and the VCO form a loop to acquire and track weak carrier signals, the adder is used for adding loop integral voltage and scanning voltage, and then inputting the sum into the VCO; the scanning voltage generation circuit analyzes and generates scanning voltage by utilizing the input weak carrier signals and signals outputted by the VCO. According to the phase-locked loop circuit, acquisition bandwidth is increased by utilizing the externally added scanning voltage in an acquisition assisting method, so that complete acquisition within Doppler bandwidth is implemented, signal Doppler bandwidth requirements are met, and high-sensitivity broadband acquisition and tracking are achieved with the assistance of digital-control scanning voltage.

An embodiment of the invention provides a determination method for a pulse repetition rate lower limiting value of synthetic aperture radar. The determination method can break through restriction of a radar working platform and working modes to obtain the accurate pulse repetition rate lower limiting value. The method comprises the following steps: determining the Doppler bandwidth of a target echo signal of the synthetic aperture radar; determining the Doppler off-centering bandwidth of the target echo signal of the synthetic aperture radar; and according to the sum of the Doppler bandwidth and the Doppler off-centering bandwidth, determining the pulse repetition rate lower limiting value of the synthetic aperture radar.

An azimuth signal reconstruction method for a Synthetic Aperture Radar (SAR) is provided. A first Signal Noise Ratio (SNR) amplification factor of a first channel transfer function matrix is determined according to the first channel transfer function matrix, and an equivalent doppler bandwidth is determined according to the SNR amplification factor; a second channel transfer function matrix corresponding to each doppler frequency point is determined according to the equivalent doppler bandwidth and the first channel transfer function matrix; and a spectrum filter for extracting a doppler spectrum is determined according to the second channel transfer function matrix corresponding to each doppler frequency point, a premeasured aliasing spectrum and an original spectrum corresponding to the aliasing spectrum, the spectrum filter being configured to extract the doppler spectrum in an azimuth signal. An azimuth signal reconstruction device for the SAR is further provided.