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This paper address ground-moving target indicator (GMTI) radar operation in the presence of strong multipath spread-Doppler clutter (SDC). Spacetime adaptive processing (STAP) for single-input-single-output (SIMO) radar is designed to mitigate direct-path SDC which leaks into the sidelobes of a moving radar platform. However, multipath SDC often returns via the receiver mainlobe and cannot be suppressed...
The problem of a point target detection masked by clutter distributed over range and Doppler, including the range and Doppler of the target, is considered for a multimode propagation scenario commonly encountered in quasimonostatic HF over-the-horizon radars (OTHR). Here, a clutter signal spread in Doppler frequency due to propagation via a disturbed ionospheric layer competes with a target and narrowband...
We compare several multiple-input multiple-output (MIMO) radar transmission schemes, including code division, time division and Doppler frequency division multiplexing approaches, for ground moving target indication (GMTI). To utilize probing waveforms with low sidelobe levels for range compression, we transmit sequences specifically designed to have low correlation levels. At the receiver side, we...
Recently discovered bounds for the clear-area available in the ambiguity domain for a MIMO radar waveform set are shown to be a significant limitation in radar applications having extended scatterer distributions. These limitations are demonstrated using an example from an experimental MIMO over-the-horizon radar. Two candidate waveform classes; time-staggered LFMCW, and frequency-staggered LFMCW,...
Multiple-input multiple-output (MIMO) radar is an emerging technology that has the capability of providing range dependent transmit-domain degrees of freedom via receiver processing. When providing these additional degrees of freedom for target tracking, MIMO radar exhibits a lower signal-to-noise ratio (SNR) when compared to that of traditional single-input multiple-output (SIMO) phased array radar...
Multiple-input multiple-output (MIMO) extensions to radar systems enable a number of advantages compared to traditional approaches. These advantages include improved angle estimation and target detection. In this paper, MIMO ground moving target indication (GMTI) radar is addressed. The concept of coherent MIMO radar is introduced. Comparisons are presented comparing MIMO GMTI and traditional radar...
We analyse an iterative adaptive multiple-input-multiple-output (MIMO) radar receiver in the situation where a K L-variate adaptive transmit-receive beamformer is structured as the Kronecker product of a K-variate (transmit) and an L-variate (receive) beamformer. We present results for the special case of two clutter propagation modes separated in elevation angle, where the direction-of-departure...
We report results from an experiment that applied multiple-input multiple-output (MIMO) waveform techniques to over-the-horizon radar (OTHR). The experiment objective was to demonstrate that adaptive transmitter beamforming could be used to reject spatially discrete radar clutter. In MIMO radar architectures, conventional or adaptive transmitter beamforming occurs following waveform transmission,...
In multiple-input multiple-output (MIMO) radar, the efficiency of target detection in clutter that is distributed over a certain range bin-Doppler frequency region depends on the sidelobe level of the waveformspsila auto- and cross-ambiguity functions within this region. We introduce the MIMO ambiguity function as the sum of all auto- and cross-ambiguity functions of the K MIMO radar waveforms, with...
Multiple-Input, Multiple-Output (MIMO) radars enhance performance by transmitting and receiving coded waveforms from multiple locations. To date, the theoretical literature on MIMO radar has focused largely on the use of ldquoorthogonal waveforms.rdquo Practical approaches to approximate orthogonality (e.g., via waveforms characterized by low cross-correlation and low autocorrelation sidelobe levels)...
This paper discusses two adaptive spatial processing approaches that have been recently proposed for mitigating spread-Doppler clutter in skywave over-the-horizon (OTH) radar. The first is slow-time MIMO (SLO-MO) STAP which uses conventional waveforms that are phase-coded so as to be orthogonal after Doppler processing at the receiver, i.e. in ldquoslow-time.rdquo SLO-MO STAP is proposed as a means...
In this paper we consider the issue of adaptive transmission and detection for MIMO radars operating under clutter with unknown covariance. In particular, we show that the availability of a set of secondary data allows defining constant-false-alarm rate (CFAR) receivers starting upon a family of previously known non-adaptive structures. We also show that, if the clutter correlation remains constant...
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