A wavelet transform technique is used to reduce (compress) the dimensionality of the covariance matrix as well as signal snapshots in space-time adaptive processing (STAP) to cut the computational demand. The algorith...
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ISBN:
(纸本)9780780393110
A wavelet transform technique is used to reduce (compress) the dimensionality of the covariance matrix as well as signal snapshots in space-time adaptive processing (STAP) to cut the computational demand. The algorithm is tested using both simulated airborne radar data generated by the high fidelity airborne radar simulation software, RLSTAP, as well as real airborne radar data collected by the MCARM system. It shows that while the computational demand is reduced by as much as 85%, there is no sacrifice to signal detection. Unlike existing dimensionality-reduced algorithms which are based on certain assumptions and lead to partially adaptive STAP, the proposed algorithm, compressed STAP (CSTAP), does not require any assumptions, so is still fully adaptive.
Trex Enterprises has developed a passive millimeter-wave imaging system incorporating a number of new technologies. The system has a pupil-plane architecture that uses a phasedarray, flat panel antenna and a phase pr...
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ISBN:
(纸本)0819449369
Trex Enterprises has developed a passive millimeter-wave imaging system incorporating a number of new technologies. The system has a pupil-plane architecture that uses a phasedarray, flat panel antenna and a phase processor based upon microwave optics. The production and operation of a 232-element W-band phasedarray and processor poses a number of technical problems including minimizing losses in the front end and adjusting the phase lengths of the processor. The system also has 192 frequency processor cards that perform real-time Fourier analysis of W-band signals over an 18 GHz bandwidth using millimeter-wave optics. Production of a suitable phase and frequency processor in large quantities that form good beams and maintain signal strength requires the adoption of new materials and design strategies. The refinement of these technologies at W-band frequencies allowed Trex Enterprises to produce an imager that is both compact and suitable for large-scale production. In this paper, we will discuss the design and production of the millimeter-wave components unique to this system architecture. We will also present the performance of these components and how they affect the performance of the millimeter-wave imager as a whole. An integrated front end is tested to determine the accuracy of the beam-forming network in producing antenna patterns.
A coherent array imaging method is described that uses small groups of adjacent array elements called subarrays. For each firing event, only one subarray is used for transmit and receive, and all elements of the subar...
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ISBN:
(纸本)0780374029
A coherent array imaging method is described that uses small groups of adjacent array elements called subarrays. For each firing event, only one subarray is used for transmit and receive, and all elements of the subarray transmit and receive in parallel. phased array processing is used to focus and steer the subarray beam in transmit and receive. A sufficient number of beams are acquired such that the Nyquist sampling criteria is met for the subarray. The beams acquired from each subarray are upsampled, filtered, and combined with beams from all the other subarrays to form the final high-resolution image. A subarray-dependent reconstruction and restoration filter is applied to the subarray beams. The method significantly reduces the front-end hardware complexity compared to fall phasedarray imaging. Experimental results demonstrate the performance of the proposed method.
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