Aimed at the performance testing of amplitude and phase in outfield for T/R modules on active phased array radar, a test scheme on T/R modules based on mid- field measurement technique is presented, and the test system is accordingly developed. The test system takes full advantage of own resources of the radar, and applies the relative measurement of amplitude and phase based on normalization and array unit weighting to analyze collecting data. As a result, the absence of standard data is avoided, the flexibility and adaptability in outfield measurement is greatly improved. Theoretical analysis and measurement results show that the testing system has many advantages, such as simple operations, rapid fault location and lower site requirements. It is proved to achieve a kind of adjoint testing support methods at a low cost.
The traditional phase center offset antenna (DPCA) technology has strict limitations on carrier velocity, pulse repetition frequency and phase center distance, which greatly restricts its application in the detection of synthetic aperture radar moving targets. For three-channel SAR system, an adaptive phase center offset antenna (ADPCA) based on ΣΔbeam is proposed to effectively suppress clutter. Simulation results show that under the background of strong clutter, it can effectively suppress clutter, improve the detection performance of weak targets, and verify the effectiveness of ADPCA moving target detection method.
KEYWORDS: Reconstruction algorithms, Error analysis, Synthetic aperture radar, Signal to noise ratio, Computer simulations, Image compression, Signal processing, Statistical analysis, Signal attenuation, Analytical research
The SAR DPCMAB(Displaced Phase Centers Multiple Azimuth Beams mode) can increase the sampling rate in the azimuth direction,whereas, it brings the problem of non-uniform sampling. Using spectrum reconstruction algorithm can regain the spectrum of uniform sampling signal. However, as the influence of interferential factors produced during the operation of SAR system, such as channel characteristics inconsistency, sampling time deviation, random noise etc, spectrum noise is appended to the reconstruction spectrum resulting in the loss of reconstruction accuracy. The paper analyses the relationship between interference factors and reconstruction error by researching spectrum reconstruction of non-uniformly sampled LFM signals affected by interferential factors. Reconstructed spectrum influenced by interferential factors is obtained in the simulation. Further more, we present the relationship curve between spectral bias and interference factors. The simulation results show that the reconstruction errors grow linearly with the enhance of the interferential factors and approach to the spectral bias of non-uniformly sampled signal finally.
To solve the problem of velocity ambiguity caused by over high azimuth velocity in the conventional SAR/GMTI system, a kind of multi-channel interferometric SAR/GMTI scheme solving the radial velocity ambiguity of moving target is presented in this paper. This method sets up four non-uniformly interval receiving channels and designs each channel spacing reasonably. Interferometric cancellation is carried out on the sub image of two echo signal, then it can get two velocity sets, and the intersection of the two sets is the correct estimation of the target velocity. Thus, the problem of velocity ambiguity is solved effectively and the radial velocity of the target is estimated correctly. Analysis and computer simulation demonstrates the validity of the method.
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