BendixKing IN-862A System RDR-2100 - Manual (Page 18)

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Effective Date: 9/98 RDR 2100 Pilot's Guide: Rev 1
Attenuation can also be a problem when flying in a large area of general
rain. If the rain is moderate, the radar beam may only reach 20 or 30
miles before it is fully attenuated.
The pilot may fly along for many miles seeing the same 20-30 nautical
miles of precipitation ahead on the radar when, actually, the rain may
extend a great distance. In order to aid in reducing the effects of precipita-
tion attenuation, the RDR 2100 contains sophisticated weather attenua-
tion compensation circuitry. The attenuation compensation feature is
totally automatic in the Wx/WxA mode of operation and requires no pilot
action to activate other than selecting Wx/WxA mode of operation. The
compensation logic operates between 3 to 320 nautical miles, whenever a
level 2 (yellow), 3 (red) or 4 (magenta) echo is displayed. The compen-
sation circuits cause the software to measure each individual cell return
and increase each individual cell return independently while the antenna
scans the sector containing heavy rain. The compensation circuitry
allows the radar beam to effectively look deeper into and through heavy
rain to search for possible storm cells beyond. While attenuation compen-
sation does not eliminate precipitation attenuation, it does allow the radar
to see through more rain at short ranges where every bit of weather infor-
mation possible is needed. If there is suspicion that the radar is attenu-
ating due to precipitation, exercise extreme caution and ask ATC what
they are showing. Often the ground based ATC controller’s radar will have
a better overall picture of a large rain area and the pilot can compare the
controller’s information with his own radar picture to avoid the strongest
cells in a general area of rain.
Theory of Operation
RDR 2100 PG 3/12/07 3:45 PM Page 14