TM 11-5840-281-12-1
2-15. EMERGENCY PROCEDURES. (CONT)
RANGE FAILS
When in search operation and any one range fails, the next shorter range may be off-centered by performing the
following operations.
1. Place RANGE MILES switch (1) to next lower range.
2. Place PPI CENTERING NORM-OFFSET switch (2) to OFFSET position.
3. Adjust PPI CENTERING HORIZ control (3) to position display (4) horizontally.
4. Adjust PPI CENTERING VERT control (5) to position display (4) vertically.
5. Place PPI CENTERING NORM-OFFSET switch (2) to NORM position after display (4) is offset.
10-DEGREE ELEVATION FAILS
When In precision approach operation, with SCAN MODE switch (6) in NORM position and 10-degree elevation display
fails, place SCAN MODE switch (6) to 350 EL position.
NOTE
The accuracy and resolution will be reduced. If both 10- and 35-degree elevation
displays fail, use azimuth display for azimuth corrections, if possible.
ALL PRECISION MODES FAIL
When in precision mode operation, with SCAN MODE switch (6) in NORM, 350 EL, 600 AZ, or SIMULT position and all
functions fail, operate the radar in search mode by placing SCAN MODE switch (6) to SEARCH position.
NOTE
When in the search mode of operation, directional information may be used to
make airport surveillance radar (asr) approaches. No elevation data is used.
This operation is not as accurate as the precision approach operation. The
accuracy can be improved by using as short a range as possible and offset
centering described in RANGE FAILS.
When any of the controls on the master control-indicator that control the radar
set group fail, such as the SCAN OR TRANSMITTER switches, operation can be
continued by interchanging the slave control-indicator with the master. When
operating in a landing control central system, an indicator (master) selector 1 or
2 switch is provided. (Refer to TM 11-5895-474-12 addendum.)
2-16. JAMMING AND ECM PROCEDURES.
The radar receiver can receive signals, other than the return signal (echo) of the transmitter, provided they are in the
correct frequency range. Unwanted signals produce wrong information on the radar display, or they may clutter the
display with so much interference that the targets cannot be distinguished. Deliberate generation of such unwanted
signals is called electronic countermeasures (ecm) or jamming. There are two types of jamming: transmission and
reflected.
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