Chapter 6 ______________________________________________________ Processing Algorithms
VAISALA______________________________________________________________________ 217
6.3.2 Range Averaging and Clutter
Microsuppression
The next step (optional) is to perform range averaging. Range averaging
can be performed over 2, 3, ..., 16 bins. This is accomplished by simply
averaging the T
0
, R
0
, R
1
and R
2
values. This reduces the number of bins in
the final output to save processing both in the RVP900 and in the host
computer.
At the user's option, the range averaged data can be restricted to include
only those bins which have an estimated clutter-to-signal ratio that falls
within the CCOR threshold interval. By excluding isolated point clutter
targets from the range average the sub-clutter visibility of the averaged
data is increased. Specifically, the Doppler test that is applied to each bin
in order that it contribute to the overall sum is:
The total power T
0
is conserved after the exclusion of the isolated point
clutter targets.
6.3.3 Reflectivity
The corrected reflectivity Z is output using a log scale based on the
following equation:
This equation is simply a dB version of the familiar radar equation for
distributed targets. The relationship between the measured autocorrelation
function, the received signal and the noise can be expressed as:
where g
t
and g
r
represent the transmitter and receiver gains, S is the
average back scattered power from the targets and N is the measured
average noise power. Neglecting attenuation and the contribution of
ground clutter (for the moment), the radar equation can be written as.
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