Pre-Doppler direct data domain approach to STAP

In the direct data domain (D3) approach to space-time adaptive processing, the data corresponding to each range cell is processed individually for interrogating the presence of a target. The technique assumes no statistical properties for the data or clutter. This paper is intended to enhance the use of data domain approaches by introducing the pre-Doppler concept which allows the maximum potential of the D3 approach to be achieved by increasing the signal-to-interference ratio at the output. In previous related work, this was carried out in an ad hoc form which would not always guarantee a solution. This issue is resolved in this study by establishing a clear mathematical foundation via a vector space-based approach. This enables us to form rules for constructing a set of linearly independent basis vectors to represent the basis for the signal subspace excluding the signal of interest.