USER’S MANUAL__________________________________________________________________
214 _________________________________________________________________ M211322EN-D
with -40 dB power without any clutter and without any GMAP filtering.
The graph at the upper right shows the same spectrum with 0 dB of clutter
power added for a clutter width of 0.012 (0.3 m/s at S band, 1000 Hz PRF).
This is a CSR of 40 dB. The panel at the lower left shows the weather
signal after GMAP filtering.
In each of the moment plots, there are several values that are displayed.
The left-most num-ber shows the value at the range cursor which is
positioned as indicated by the vertical line. To the right, the "m" value is
the mean and the "s" value the standard deviation as averaged over all
range bins (1000 in this example). For velocity these are in normalized
units expressed as a fraction of the Nyquist interval. For reflectivity the
values are in dB.
Some key points are:
- The mean velocity is correctly recovered as expected (the "m" value
in the plot), but the standard deviation is higher (0.06 vs 0.04 in
normalized units).
- The "Cor dBZ" shows 40.2 dB of "C.Rej". This is the difference
between the "Tot dBZ" and the "Cor dBZ" values. The expected value
is 40 dB in this case. This indicates that GMAP has recovered the
weather signal in spite of the aggressive clutter filtering that is
required.
- The standard deviation of the "Tot dBZ" is greater in the weather plus
clutter (4.35 normalized units) as compared to the weather-only case.
This is caused by the fluctuations in the clutter power in the Gaussian
clutter model.
- The standard deviation of the Cor dBZ after GMAP filtering, while
not as low as for the weather-only case are lower than the weather plus
clutter case. In other words, the GMAP processing removes some of
the high variance in the dBZ estimates that is caused by clutter, but is
not quite as good as doing nothing.
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