New signal processing developments in the detection of low-altitude windshear with airborne Doppler radar

Airborne weather radar is being developed to detect hazardous low-altitude windshear. One of the major challenges is development of signal processing algorithms which will perform satisfactorily when the weather return signal power to interfering ground clutter return power is very low. Two basic approaches which are under investigation are described. One approach is to estimate wind speed from the radar returns using an extended Prony-based method without a clutter rejection prefilter. Alternatively, improved clutter prefiltering techniques are being investigated based on an adaptive noise canceller implementation of the least mean square (LMS) algorithm. Results are presented to illustrate some of the capabilities of each. Also described is a method for merging flight experimental clutter return data with a simulated microburst return based on a radar measured windfield. This allows very rare low reflectivity weather events to be studied in the presence of actual clutter data.