STAP

This paper describes initial findings from a research program to investigate the main beam and sidelobe impulse responses of large phased array antennas and reflector antennas typically used for radar applications. Particular emphasis is given to the way that the impulse response changes from the main beam to the sidelobe region of the antenna. Time-domain effects affect transmit and receive waveforms and therefore advanced signal processing algorithms such as adaptive digital beamforming (ADBF) and space time adaptive processing (STAP) are used. GTRI has instituted an internal research program to investigate the time-domain phenomenology of phased array antennas and develop computer simulation tools and measurement capability for characterizing these phenomena. We provide a brief discussion of the time-domain phenomena and the effects that antenna architecture produces. An overview of the method GTRI is using to investigate these phenomena is given. Finally, initial results of these efforts are presented

In this paper, we first present the principles of STAP and discuss the properties of optimum detector, as well as problems associated with estimating the adaptive weights such as ambiguities and the high computational cost. The performances are evaluated highlighting the influence of radar parameters on the detection of slow targets. To resolve problem of high computational cost of optimal

In this paper, we examine the feasibility of applying space-time adaptive processing (STAP) to bistatic passive radars using illuminators of opportunity. The transmitters considered are GSM base stations and are non-cooperative. Although STAP has been extensively applied to signals from pulse-Doppler radars, it was never applied to arbitrary signals arising from illuminators of opportunity. We show that by computing the appropriate mixing product, we essentially convert the signal of opportunity to a pulse-Doppler like signal, hence making the application of STAP to arbitrary signals straightforward. We finally confirm these theoretical results by using real measurements.

In this paper, we first present the principles
of STAP and discuss the properties of
optimum detector, as well as problems
associated with estimating the adaptive
weights such as ambiguities and the high
computational cost. The performances are
evaluated highlighting the influence of radar
parameters on the detection of slow targets.
To resolve problem of high computational
cost of optimal STAP, reduced-rank
methods are used. And to resolve Doppler
ambiguities, staggering of PRF is used. The
simulation results are presented and the
performances of STAP are discussed. In
addition, the effect of an interfering target is
analyzed. The performances of detection are
discussed using two parameters: power and
direction of the interfering target. Numerical
evaluation is based on two models of
staggering PRF: quadratic and pseudorandom,
with two methods for reducing
rank: Principal Components and SINR
metric.
It was shown that the primary target is
completely masked if the interfering target is
powerful and this for any direction of the
second target. It was also proven as when
this one is located according to particular
directions of the jammers, detection is
largely degraded. To cure these problems,
one considered an analysis of the staggered
PRF of the STAP with the two methods
which showed their effectiveness.