Vaisala RVP900, Руководство пользователя

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Variable Width, Single Slope (Type 1)
RVP900 supports variable-width, frequency-domain clutter filters. These filters perform the
same spectral interpolation as the fixed–width filters, except that their notch width
automatically adapts to the clutter.
The filters are characterized by the
Width and EdgeMinPts parameters in the Mf menu,
except that the Width is now interpreted as a minimum width.
The Hunt parameter allows you to choose how far to extend the notch beyond Width to
capture the clutter power. Setting Hunt=0 converts a variable–width filter to a fixed– width
filter.
The algorithm for extending the notch width is based on the slope of adjacent spectral
points.
• The beginning (
Width-1
) points away from 0, the filter is extended in each direction
as long as the power continues to decrease in that direction, up to adding a maximum
of
Hunt
additional points.
• If you run with a fixed
Width=3
filter, try experimenting with a variable
Width=2
and
Hunt=1
filter.
• If the original fixed width occasionally fails, but you are reluctant to increase it to cover
those rare cases, try selecting a variable
Width=2
and
Hunt=2
filter.
In general, make your variable filters "wider" by increasing Hunt rather than by increasing
Width
. This preserves more flexibility in how they can adapt to whatever clutter is
present.
Gaussian Model Adaptive Processing (GMAP) (Type 2)
This is the most advanced form of clutter filtering and moment estimation. See 7.3.5 Clutter
Filtering Approaches (page 189) .
For GMAP processing, you must specify the spectrum width of clutter. Note that the
algorithm is not very sensitive to the exact value. You should configure several widths to
cover the antenna rotation rates that are commonly used. It is useful to turn off clutter
filtering (select the all pass filter
#0 ) and then look at measurements of the clutter width
while the antenna is rotating using, for example, the Ascope utility or application software
such as IRIS.
Whitening Parameters for Tx :Random
The values in the next line define a secondary SQI threshold that is traditionally used to
qualify LOG data in the Random Phase processing mode. The secondary SQI threshold is
applied uniformly in all processing modes when reflectivity data are specified as being
thresholded by
SQI .
Secondary SQI Threshold Slope :0.50 Offset:-0.05
RVP900 User Guide M211322EN-J
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