Multi-PRI signal processing for the Terminal Doppler Weather
Radar. Part I: Clutter filtering
Multiple pulse-repetition interval (multi-PRI) transmission is part of
an adaptive signal transmission and processing algorithm being
developed to aggressively combat range-velocity ambiguity in weather
radars. In the past, operational use of multi-PRI pulse trains has
been hampered due to the difficulty in clutter filtering. This paper
presents finite-impulse-response clutter filter designs for multi-PRI
signals with excellent magnitude and phase responses. These filters
provide strong suppression for use on low-elevation scans and yield
low biases of velocity estimates so that accurate velocity dealiasing
is possible. Specifically, the filters are designed for use in the
Terminal Doppler Weather Radar (TDWR) and are shown to meet base data
bias requirements equivalent to the Federal Aviation Administration's
specifications for the current TDWR clutter filters. Also an adaptive
filter selection algorithm is proposed that bases its decision on
clutter power estimated during an initial long-PRI surveillance scan.
Simulations show that this adaptive algorithm yields satisfactory
biases for reflectivity, velocity, and spectral width. Implementation
of such a scheme would enable automatic elimination of anomalous
propagation signals and constant adjustment to evolving ground clutter
conditions, an improvement over the current TDWR clutter filtering
system.
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