20-09-2009, 04:01 PM
Space-Time Adaptive Processing: Fundamentals
ABSTRACT
Space-time Adaptive Processing (STAP) is a signal processing technique most commonly used in radar systems. It involves adaptive array processing algorithms to aid in target detection. Radar signal processing benefits from STAP in areas where interference is a problem (i.e. ground clutter, jamming, etc.). Through careful application of STAP, it is possible to achieve order-of-magnitude sensitivity improvements in target detection.STAP involves a twodimensional filtering technique using a phased-array antenna with multiple spatial channels. Coupling multiple spatial channels with pulse-Doppler waveforms lends to the name space-time. Applying the statistics of the interference environment, an adaptive STAP weight vector is formed. This weight vector is applied to the coherent samples received by the radar.In this lecture, we present the principles of spacetime adaptive processing (STAP) for radar, applied to moving target indication. We discuss the properties of optimum STAP, as well as problems associated with estimating the adaptive weights not encountered with spatialonly processing (i.e. beam forming) .
1 INTRODUCTION What is Space-Time Adaptive Processing (STAP)? Space-Time Adaptive Processing (STAP) is a signal processing technique used to suppress the effects of cochannel interference, ISI, and jammers in wireless communications systems. From the implementation of STAP algorithms, greater capacity gains and communication quality can be realized . The fundamental principle in all STAP algorithms involves the usage of multiple receive antennas on the receiving platform. Spacing the antennas apart by at least half the wavelength of the desired signal provides space diversity, which helps mitigate the effects of fading. Furthermore, the incoming signals on each antenna element are adaptively weighted using a variety of algorithms in order to steer the antenna gain towards the desired signals while nulling the signals from unwanted noise and interference.
