TM 11-4920-292-15
( I1 - I2 )
i. Rotate turntable until HEADING and
B MAG = B +
2
ERROR readout indicates 0 DEGREES 10
MINUTES. Set turntable azimuth scale to 0
NOTE
degree. Record ERROR readout indication.
The remaining steps of this test must
be completed within 30 minutes to
j. Rotate turnable to heading of 90, 180, and
minimize errors due to shifting of
270 degrees. Record ERROR readout indication
earth's magnetic field.
at each heading.
s. Set POWER ON-POWER OFF switch to
k. Add the four recorded ERROR readout
POWER OFF.
indications algebraically and divide the sum by
t. Disconnect cable W2 from turntable as-
4. Record the resultant value as index error
sembly.
( I1).
u. Without moving tripod, remove turntable
l. Rotate turntable to sight a target at a dis-
assembly from tripod.
tance of at least 1/2 mile, Record turntable azi-
v. Set up and level monitor assembly on
muth scale indication as target bearing (B).
tripod as shown in figure 11-4.
NOTE
w. Connect cable W2 between control con-
Target elevation should be within 5
sole connector 1J3 MONITOR and monitor as-
degrees of horizontal, Use a flagpole or
sembly.
corner of building for target.
x. Set POWER ON-POWER OFF switch to
NOTE
POWER ON.
Power must be off during the follow-
y. Rotate monitor to sight target.
ing operation if connector on magnetic
z. Set aximuth scale of monitor to recorded
azimuth reference detector is discon-
true magnetic bearing (BMAG) of target.
nected.
aa. Adjust VOLTS ADJUST control for 23.5
m. Remove magnetic azimuth reference
volts on EXC VOLTS meter.
detector from top of turntable assembly mount-
ab. Rotate monitor to headings of 0, 90, 180,
ing plate and remount in inverted position so
and 270 degrees and record ERROR readout
that the telescope is below the turnable assembly
indication at each heading,
mounting plate,
ac. Determine the monitor index error by
n. Rotate turntable to sight on original tar-
adding the four recorded error algebraically
get.
and dividing the sum by 4.
o. Set aximuth scale to previously recorded
ad. Determine the corrected monitor index
target bearing (B).
error by algebraically subtracting the synchro
index error (para 11-13k) from the monitor
p. Rotate turntable to headings of 0, 90, 180,
index error (ac above) to determine true index
and 270 degrees. Record ERROR readout indi-
error. True index error shall be 0 6 minutes.
cation at each heading, disregarding the HEAD-
ING readout indications (at 90- and 270-degree
headings, the HEADING readout indications
a. Rotate monitor to a 0-degree heading.
are 270 and 90, respectively).
b. Set E1 CHECK, E2 CHECK, and AREA
q. Add the four recorded errors algebraically
COMP controls to 500,
and divide the sum by 4. Record the resultant
value as index error (I2).
c. Set E1 NORM-E1 REV switch to E1
NORM.
r. Determine and record the true magnetic
d. Set E2 NORM-E2 REV switch to E2
bearing of the target (BMAG) by solving the fol-
NORM.
lowing equation:
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