PART 1 - DESCRIPTIVE
48. Radar ranging (A.R.I. 5820)
NOTE.-The aircraft should not be landed with the
system switched NO.
(a) The radar ranging ON/OFF switch (35) on the port shelf
controls the system; an adjacent magnetic indicator shows
white with the system in use and black when its use is
(b) Radar ranging automatically provides the GGS with
target range information within the limits of 200-800
yards. The radar searches from maximum range down
to minimum range until a target is found. If no target
is found within the search area the search is automatically
repeated When a target is found the radar locks on to it,
and a blue light (54) on the right of the GGS lights up
to indicate this.
(c) A spring-loaded TARGET REJECT IN-OUT switch
(18) is on the port wall. Its function is to unlock the
radar from an unwanted target or to check that it is
locked on to the correct target. When IN is selected, the
radar unlocks from the target and searches inward to
minimum range. If no fresh target is found the normal
search cycle commences whether the switch is retained
at IN or not. When OUT is selected the radar unlocks
from the target and searches outwards to maximum
range. It will remain at maximum range if the switch is
retained at OUT but when released, the normal search
cycle is commenced.
(d) To check that the radar is locked on the correct target
set the span knob of the GGS that of the target type.
If the correct target is being ranged the GGS graticule
should just encompass the target span. If the target span
extends beyond the graticule (over ranging) or does not
extend to the graticule (under ranging), the wrong target
is being ranged and REJECT IN or REJECT OUT
respectively should be selected.
NOTE.-(1) When the manual twist-grip is set to a
shorter range than that of the target the
radar cannot control the graticule until the
target comes within the range set by the twist-
grip, when the radar takes over the ranging.