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

Abstract

Airborne weather radar Is being developed to detect hazardous low altitude windstmar which has been a major contributing factor in many airline crashes In this country. 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. This paper describes two basic approaches which are under Investigation. One approach is to estimate windspeed from the radar returns using an extended Prony based method without a clutter rejection pre-filter, since the fllterlng process itself can reduce the weather signal below useful Isvels. Alternatively, improved clutter pre-filtering techniques are being iwestigated based on an adaptive noise canceller implementaticm of the 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.

Low-level wind shear of wind field modeling and simulation

“…According to NASA proposed model, it set up a simplified engineering model, and conducted a computer simulation. This dissertation focused on the radar echo signal model, including wind shear echo signal model and clutter model, using the principle of Doppler frequency shifting.The proposed model should have both simulate character of the micro flow and convenient for the wind shear radar signal detection system to do simulation [1][2][3][4][5][6] .…”

Simulation and study of windshear signal in airborne pulse Doppler weather radar

“…Each echo signal of the range gate [7][8][9] is calculated by the following two formulas, that the echo signal I and Q . n represents the n-th pulse, and s T represents pulse time interval:…”