Publications

The Terminal Doppler Weather Radar (TDWR) system is designed to provide high quality low altitude Doppler radar data near airports. Ground clutter suppression will be a major challenge to supplying such high quality Doppler data. To confront this challenge the FAA has specified stringent clutter suppression requirements in the TDWR technical specifications. These specifications are designed to provide an effective clutter suppression system. In particular, the specifications require an antenna with narrow beam width and low side-lobes to minimize ground target illumination. Also, a high pass frequency filter (with a stop attenuation in excess of 50 dB) is required to reduce stationary clutter. FInally, a clutter reisdue map editing system is used to remove remaining clutter. This report describes the algorithms used to generate and use the clutter residue editing system. The major issues are discussed followed by a description of the algorithms designed to address these issues. Finally, preliminary experimental results using a clutter residue map are presented.

Low altitude wind shear (LAWS) has been recognized as a major cause of commercial airline aircraft accidents in the United States. The FAA is actively conducting the Terminal Doppler Weather Radar (TDWR) program to detect and identify dangerous wind fields at and around airports using Doppler radar techniques. Clutter poses a major challenge to successful operation of such a system due to the need to measure the return from low cross section wind tracers in the presence of close-in clutter from stationary objects. The paper describes the overall LAWS detection scenario with particular emphasis on microburst and gust front detection before presenting detailed experimental and analytical results on the suppression of ground clutter using a combination of: 1) subclutter visibility in excess of 50 dB by the use of high pass digital filters with narrow stopbands, and 2) interclutter visibility (ICV) algorithms which utilize the spatially distributed nature of the weather phenomena being measured, and 3) pencil beam antennas with readily achievable sidelobes.