TM 11-5840-281-12-1
2-4. SEARCH OPERATION. (CONT)
Although there is no definite way for the operator to determine if video clutter Is being caused by ground returns or
precipitation, there are a number of actions that can be taken to reduce clutter. If clutter is being caused by ground
returns, perform steps 1 through 6 in the order of sequence until return signal from target being tracked can be readily
followed on the crt. When clutter is being caused by precipitation, or when steps 1 through 5 do not satisfactorily reduce
clutter, proceed with steps 7 through 10 in the order of sequence until return signal from target being tracked can be
readily followed.
1.
Place STC switch (1) to ON position.
2.
Rotate EL TARGET control (2) clockwise from WIDE to NARROW position.
3.
Place FTC switch (3) to LIN position.
4.
Taking care not to lose target, rotate IF GAIN AZ (4) and IF GAIN EL (5) counterclockwise.
5.
Place TRANSMITTER switch (6) to NAR PLS position.
6.
Press HV ON indicator switch (7).
7.
Place STC switch (1) to OFF position.
8.
Place FTC switch (3) to LOG position.
9.
Rotate IF GAIN AZ (4) and IF GAIN EL (5) controls fully clockwise (maximum gain).
NOTE
When ANT POL switch is placed in CIR position, maximum detection range is reduced
approximately 20 percent. Return to LIN position when no longer required.
10.
Place ANT POL switch (8) to CIR position. CIR indicator (9) will light and LIN indicator (10) will extinguish.
2-7. PRECISION APPROACH OPERATION.
The precision approach function is used to control aircraft along a courseline and glidepath to the prescribed gca
minimums, or theoretically to within 20 feet of runway touchdown. This is accomplished with the SCAN MODE switch on
the master control-indicator in NORM 350 EL, 600 AZ, or SIMULT positions. The precision approach display Is a dual
scan (beta) type. Ranges of 5, 10, 20, and 40 nautical miles, with range marks at 1-mile intervals for 5- and 10-mile
ranges and 5 miles for ranges of 20 and 40 miles, can be selected by positioning the RANGE MILES switch. Two sets of
preset electronic cursors are available on the azimuth and elevation displays, providing separate glidepath and
courseline Indications for each of two runway approaches. For right-of-runway coverage, the azimuth cursor will curve
down and for left-of-runway coverage, it will curve up. The elevation cursor is turned down in both configurations.
By positioning the SCAN MODE switch to NORM, 350 EL, or 600 AZ positions, azimuth sectors of 30 and 60 degrees
may be scanned. The precision approach is accomplished with the master control- indicator. When operating in
SIMULT mode, the slave control-indicator crt display will have a ppi scan with IFF video capability. Simultaneous Mode
Operation is explained in paragraph 2-9.
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