Processing and evaluation of Multichannel Airborne Radar Measurements (MCARM) measured data

Rome Laboratory's (RL's) Multichannel Airborne Radar Measurements (MCARM) program [1] has collected clutter and target data employing an L-band airborne phased array radar testbed. The data collection is at the output of an electronically steered active array mounted on BACl-11 aircraft. The MCARM array has 16 columns, each consisting of two four-element subarrays. Each subarray has its own output or is combined into a single output per column with up to 24 outputs for the array. Space-time adaptive processing (STAP) techniques [2] simultaneously combine the signals from the elements of an array antenna and pulses of a radar waveform to suppress interference and provide target detection. To obtain adequate clutter power with the limited power-aperture product of the array for STAP analysis, the transmit mainlobe power can be focused in the receive beam sidelobe region or the transmit beam can be spoiled for broader angular coverage. In addition, the data is collected at different platform altitudes and radar waveforms over different terrain. The performance improvement achievable against Doppler-spread clutter that can be achieved with STAP using the L-band data is demonstrated. We present processing results of representative MCARM data files (with different look directions and with targets of opportunity and synthetic targets) to demonstrate that the adaptive processing can help to detect targets in a nonhomogeneous environment. The limitations of the number of independent clutter samples in estimating the covariance matrix and its impact on target cancellation are examined by processing tiles with real and synthetic targets.