User's Manual

RVP8 User’s Manual
October 2005
TTY Nonvolatile Setups
3–12
those transmit polarizations should be used whenever there is more than one choice
available. Thus, these selections only apply to the Alternating and Simultaneous
transmit modes. Likewise, answering YES to Co-Rcv and/or Cx-Rcv means to use the
received data from the co-channel or cross-channel. The receiver question will only
appear when dual simultaneous receivers have been configured.
A typical installation might use H-Xmt:YES, V-Xmt:YES, Co-Rcv:YES, Cx-Rcv:NO.
This will compute (T/Z/V/W) from the co-polarized receiver using both H&V
transmissions. Including both transmissions will decrease the variance of (T/Z/V/W);
although some researchers prefer excluding V-Xmt because that is more standard in
the literature. Also, if your polarizations are such that the main power is returned on
the cross channel, then you will probably want Co-Rcv:NO and Cx-Rcv:YES.
DualRx – Sum H+V Time Series: NO
In dual-receiver systems, you may choose whether the (H+V) time series data consist
of the sum of the “H” and “V” samples or the concatenation of half the “H” samples
followed by half the “V” samples. The later is more useful when custom software is
being used to analyze the data from the two separate receive channels.
3.2.3 Mf — Clutter Filters
Residual clutter LOG noise margin: 0.15 dB/dB
Whenever a clutter correction is applied to the reflectivity data, the LOG noise
threshold needs to be increased slightly in order to continue to provide reliable
qualification of the corrected values. The reason for this is that the uncertainty in the
corrected reflectivity becomes greater after the clutter is subtracted away.
For example, if we observe 20dB of total power above receiver noise, and then apply
a clutter correction of 19dB, we are left with an apparent weather signal power of
+1dB above noise. However, the uncertainty of this +1dB residual signal is much
greater than that of a pure weather target at the same +1dB 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 0.15dB/dB, the LOG threshold would be increased by 19x0.15 = 2.85dB.
This helps eliminate noisy speckles from the corrected reflectivity data.
Spectral Clutter Filters
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Filter #1 – Type:0(Fixed) Width:1 EdgePts:2
Filter #2 – Type:0(Fixed) Width:2 EdgePts:2
Filter #3 – Type:0(Fixed) Width:3 EdgePts:3
Filter #4 – Type:1(Variable) Width:3 EdgePts:2 Hunt:3
Filter #5 – Type:2(Variable) (Gaussian Model) Spectrum width: 0.200 m/sec
Filter #6 – Type:2(Variable) (Gaussian Model) Spectrum width: 0.300 m/sec
Filter #7 – Type:2(Variable) (Gaussian Model) Spectrum width: 0.500 m/sec
These questions define the heuristic clutter filters that operate on power spectra
during the DFT-type major modes. Filter #0 is reserved as “all pass”, and cannot be
re–defined here. For filters #1 through #7, enter a digit to choose the filter type,
followed by however many parameters that type requires. The three filter types are
all described in detail in Section 5.2.5.