Performance analysis of post-Doppler STAP

The multi-bin post-Doppler space-time adaptive processing (STAP) approach (AKA ldquoExtended Factored STAPrdquo) is a suboptimal technique for mitigating clutter in airborne radar systems that provides significant efficiency gains over optimal fully adaptive processing. The use of multiple Doppler bins in combination with the spatial degrees of freedom (DoFs) partially captures the space-time correlation of the clutter which can lead to significant processing performance improvement over singlebin (i.e. Doppler specific, spatial-only, ldquoFactored STAPrdquo) processing. In this paper, the origin of this improvement is identified analytically by developing a general expansion of the critical signal-to-interference-plus-noise ratio (SINR) loss performance metric as a function of clutter strength. It is shown that for multi-bin implementations, the dominant term is independent of clutter strength leading to asymptotically constant performance as a function of this parameter. However, this term vanishes for the single-bin case leading to performance dictated by a term inversely proportional to clutter strength. Thus, single-bin performance is highly sensitive to clutter strength while multi-bin is not. These results are used to identify limits on allowable maximum clutter strength as a function of scenario parameters so that the highly efficient single-bin approach provides performance within a given limit (e.g. 3 dB) of the optimal fully adaptive result.