Vaisala RVP900 - Load Clutter Filter Flags (LFILT)

When the number of output words is large there is a possibility that the internal buering
within RVP900 may overflow and data may be lost. Due to internal memory limitations, the
product (BxN) must be less than 12000. A bit in the latched status word indicates when time
series overflows occur. In such cases, the correct number of words are still output, but they
are all 0 after the point at which overflow was detected. See 8.10 Get Processor Parameters
(GPARM) (page 271)
8.9 Load Clutter Filter Flags (LFILT)
In the RVP9 processor, you can choose any available clutter filters independently at each
selected range.
This range-dependent clutter removal is useful when the clutter characteristics vary with
increasing range. Typically, clutter interference is most severe in the immediate vicinity of
the radar. You can choose a highly rejective
filter for near ranges, and a less rejective, or
perhaps no filter, at far ranges.
Legacy Version
In the legacy version of LFILT, the input words following the command specify the choice
of
filter to be applied at each of the selected range bins.
A
fixed size filter table is always loaded, regardless of whether the range mask (See 8.3 Load
Range Mask (LRMSK) (page 237)) is using the full number of bins. In such cases, the later
filter codes are ignored for the current range mask. However, if a longer range mask is
loaded in the future, then those later codes would apply to the correspondingly numbered
bins. In sum, each
filter code is associated with a particular bin number, not with a particular
range. The correspondence between bin numbers and ranges is made only through the
range mask.
Only the low three bits are used in each word to specify the filter number. If the L3K bit is
set in the Command, then 4200 words are loaded, otherwise only 512 words are loaded. In
both cases the last
filter choice is replicated for all bins further in range.
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
---------------------------------------------------------------
| | | | | | | | | | | | | | | | |
| |ALL| 0 1 0 0 0 | Command
|----------------------------------------|---|-------------------| (Legacy)
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
---------------------------------------------------------------
| | | | | | | | | | | | | | | | |
| | Filter #1 | Input 1
|----------------------------------------------------|-----------|
Either 512 or 4200 Words Loaded
RVP900 User Guide M211322EN-J
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