Honeywell SPZ-8000 Maintenance Manual page 266

8.1 B.
The radar system consists of two
WC-874 Controller sets the radar
MAINTENANCE
MANUAL
GULFSTRE4MIV
WC-874 Weather Radar Controllers. Each
modes, range, antenna tilt, and weather
display brightness on its respective navigation display. If one WC-874
Controller is off, the other controller will set the radar modes, range
and antenna tilt, and display a slave (SLV) annunciation on the
OFF
controller indicating that it is slaved to the settings on the ON
controller.
The controller has four snap-action pushbuttons, two rotary
switches, and three potentiometers to select and control the operation
modes of the radar system. The following paragraphs describe each of
the PRIMUS@ 870 modes and features controlled by the WC-874.
(1) Target Alert (TGT) - The TGT button allows the pilot to select or
deselect the target alert mode of the radar system. Target alert
is selectable in any WX range except 300 NM. The target alert
circuit monitors for red level or greater targets within t7.5
degrees of dead ahead. Also the target must have the following
depth and range characteristics:
(2)
Selected
Target Target
Range (NM) Depth (NM) Range (NM)
5
;:
1::
200
300
FP (Flight Plan)
2 5-55
2 - 60
4
;: - 75
4
- 100
4 1%- - 150
6 200 - 250
Inactive
2 5-55
It should be noted that while target alert is functional at the
above ranges, it is improbable that a realistic target would be
strong enough to be detected if its range exceeds five times the
displayed range. Also, note that the target alert is inactive
within the displayed range. Selecting target alert prevents
variable gain from being selected.
Ground Clutter Reduction (GCR) Mode - The scintillation frequency
of the ground radar returns is lower than that of rainfall radar
returns. A digital frequency filter is used to separate ground
returns from the 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. GCR
is
operational in WX mode and selected
ranges of 50 NM or less.
22-14-00
Page 198.93
Aug 15/91
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