Default residual clutter LOG noise margins:
Baseline : 0.15 dB/dB for Clutter/Noise above 10dB HiSignal : 1.00 dB/dB
for Clutter/Noise above 50dB
For example, if we observe 20 dB of total power above receiver noise, and then apply a
clutter correction of 19 dB, we are left with an apparent weather signal power of +1 dB above
noise. However, the uncertainty of this +1 dB residual signal is much greater than that of a
pure weather target at the same +1 dB signal level.
The Residual Clutter LOG Noise Margin allows you to increase the LOG noise
threshold in response to increasing clutter power. In the previous example, and with the
default setting of 0.15 dB/dB, the LOG threshold increases by 19 x 0.15 = 2.85 dB.
This helps eliminate noisy speckles from the corrected
reflectivity data.
The Spectral Clutter Filters define the clutter filters that operate on power
spectra during the DFT-type major modes (PPP, FFT, and RPH).
Filter #0 is reserved as all pass, and cannot be redefined here. For filters #1 to #7,
enter a digit to choose the
filter type, followed by however many parameters that type
requires. See 7.3.5 Clutter Filtering Approaches (page 189).
Spectral Clutter Filters
------------------------
Window –1:Default 0:Rectangular 1:Hamming
Code 2:Blackman 3:ExBlackman 4:VonHann 5:Adaptive
Filter #1 Type:0(Fixed) Win:1 WidthPts:1 EdgePts:2
Filter #2 Type:0(Fixed) Win:2 WidthPts:2 EdgePts:2
Filter #3 Type:0(Fixed) Win:2 WidthPts:3 EdgePts:3
Filter #4 Type:1(Variable) Win:2 WidthPts:3 EdgePts:2 HuntPts:3
Filter #5 Type:3(Gaussian Model) Win:-1 Spectrum width: 0.200 m/sec
Filter #6 Type:3(Gaussian Model) Win:-1 Spectrum width: 0.300 m/sec
Filter #7 Type:3(Gaussian Model) Win:-1 Spectrum width: 0.500 m/sec
Fixed Width Filters (Type 0)
These are defined by the following additional parameters:
Width
Sets the number of spectral points that are removed around the zero velocity term. A
Width of 1 removes the DC term. A Width of 2 removes the DC term plus 1 point on
either side. A Width of 3 removes DC plus 2 points on either side, and so on. Spectral
points are removed by replacing them with a linear interpolating line.
EdgeMinPts
The endpoints of the line are determined by taking the minimum of EdgeMinPts
past the removed interval on each side.
Chapter 5 – TTY Non-volatile Setups
105
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