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Joint Synthetic Aperture Radar and Space-Time Adaptive Processing on a Single Receive Channel

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Wide-area persistent synthetic aperture radar (SAR) video offers the ability to track ground moving targets via changes between video frames. A shortcoming is the difficulty in maintaining track when a Doppler shift places moving target returns co-located with strong clutter. We propose to augment a SAR modality with space-time adaptive processing (STAP). The wide-area SAR capability generates a large data rate, stressing on-board processing or a ground station data link; therefore, expansion to multiple radar channels for STAP can present a system bottleneck. Consequently, we adopt a multiple transmit, single receive (MISO) architecture that constrains the system data rate for down-link or on-board processing to that of a single antenna SAR system. A frequency division design for quasi-orthogonal transmit waveforms is presented; the approach maintains coherence on clutter, achieves the maximal unaliased band of radial velocities set by the pulse repetition frequency of the system, retains full resolution SAR images, and requires no increase in receiver data rate vis-a-vis the wide-area SAR modality. For N transmit antennas and Ns samples per pulse, the enhanced sensing provides a STAP capability with N times larger range bins than the SAR mode, at the cost of O(Ns) increase in computation per pulse. The waveforms investigated here for MISO operation can be adopted for a multiple transmit, multiple receive (MIMO) architecture, as well. The proposed transmission scheme and the associated signal processing are detailed, and the approach is demonstrated at X-band via both numerical simulation and airborne data collection.

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Emre Ertin

Field of Interest

“The field of interest shall be the organization, systems engineering, design, development, integration, and operation of complex systems for space, air, ocean, or ground environments. These systems include but are not limited to navigation, avionics, mobile electric power and electronics, radar, sonar, telemetry, military, law-enforcement, automatic test, simulators, and command and control."

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