Honeywell SPZ-8000 - GAIN Adjust; Ground Clutter Reduction Mode; Rain Echo Attenuation Compensation Technique Mode; Target Alert

Honeywell !&!!!!.=’
The WC-81O Weather Radar Controller contains all the controls required to
operate the PRIMUS@ 800 Weather Radar System.
The controller has three
snap-action pushbuttons,
two rotary switches, and three potentiometers to
select and control the operating
modes of the radar system. The
following paragraphs describe each of the PRIMUS@ 800
modes and features
controlled by the WC-81O.
8. B. (1) Target (TGT) Alert
- The
TGT button allows the pilot to enable/
disable the target alert
mode at the radar system. In the target
alert mode, an alert is flashed on the weather display when a red or
heavy precipitation area is detected in a 15-degree arc between 60
and 120 nautical miles ahead of the aircraft.
(2)
(3)
Ground Clutter Reduction (GCR) Mode -
The scintillation frequency of
ground radar returns is lower than that of rainfall radar returns.
A digital frequency filter is used to separate ground returns from
rainfall returns, and only the rainfall returns are displayed when
the GCR mode is selected.
Since some of the rainfall returns fall
into the same spectrum as the ground returns, there is some loss of
weather return in the GCR mode. As a result, the weather
presentation in this mode cannot be considered calibrated. However,
the GCRmode gives the pilot a dramatically improved look at weather
in terminal areas or mountainous terrain where it may be necessary
to tilt the antenna toward the ground to see weather ahead. The GCR
annunciator above the switch lights to indicate to the pilot that he
is in the GCR mode.
Rain Echo Attenuation Compensation Technique (RCT) Mode - Rain echo
attenuation compensation techniques automatically increase the
receiver gain in real time as a function of attenuation due to
penetrated rainfall to maintain system calibration. This circuit is
implemented digitally in the PRIMUS@ 800 and, in conjunction with a
digitally generated sensitivity time control (STC), a signal is
generated when the receiver gain has reached its maximum available
value.
At this time, a blue color is displayed for the remainder of
the displayed range.
This gives the pilot an unmistakablewarning
that attenuation is hiding possible severe weather areas that cannot
be accurately detected.
The RCT annunciator above the switch liqhts
to indicate
(4) GAIN Adjust
gain. AUTO
the weather
analysis or
to the pilot that he is in the RCT mode.
- The GAIN
potentiometer selects the radar receiver
GAIN calibrates the system for optimum performance in
mode.
Variable gain is used for additional weather
ground mapping.
(5) MODE Control
- The rotary MODE control is used to select one of the
following positions:
● OFF
- This position turns the weather radar system functionally
off.
22-14-00
Page 198.79
Aug 15/91
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