TM 11-6625-2440-12
d.
Power Turnoff.
LEVEL AXIS or HEADING
Frequency
(1) Set controls to positions indicated in a (2)
AXIS switch
Setting
(Hz)
through (5) above.
E ---------------------
0
0
(2) Turn off test set ac and dc power sources.
1
0.004577
2
0.009155
3-5. Latitude Earth Rate Correction
3
0.013733
4
0.018311
5
0.022888
Each position of each of the LEVEL AXIS and HEADING
6
0.027466
AXIS thumbwheel switches represents a specific
7
0.032043
frequency. Any frequency required by the platform may
F ---------------------
0
0
1
0.00057
be obtained by selecting combinations of these switch
2
0.00114
settings. A list of these specific frequencies and the
3
0.00171
thumbwheel switch settings required to obtain them is
4
0.00228
provided in a below. The requirements and method for
5
0.00285
6
0.00342
making the computations necessary to determine the
7
0.00399
thumbwheel switch setting for the specific latitude of the
test site are given in b through d below.
b. Level Axis Latitude Correction. The level axis
latitude correction frequency (F) for any earth-latitude
a.
Thumbwheel Switch Frequency Chart.
position may be determined by completing the following:
(1) Obtain the earth-latitude position (λ) of the
NOTE
test site from the local cognizant authority.
(2) Determine the cos λ to the nearest tenth
The
thumbwheel
switches
are
designated (left to right) A through F for
of a minute using sine and cosine interpolation described
each switch group.
in d below.
(3) Calculate the frequency by substituting the
LEVEL AXIS or HEADING
Frequency
value determined in (2) above for cos λ in the equation F
AXIS switch
Setting
(Hz)
= (80. 28668 cos λ) Hz.
Record the calculated
A ----------------
0
0
frequency.
1
18.75
2
37.50
(4) Using the thumbwheel switch frequency
3
56.25
chart in a above, determine the correct LEVEL AXIS
4
75.00
thumbwheel switch settings for the calculated frequency
5
93.75
and set thumbwheel switches accordingly.
The
6
112.50
sequence for setting the thumbwheel switches is as
7
131.25
B ----------------
0
0
follows:
1
2.34375
(a) Select highest A-switch setting which
2
4.68750
represents but does not exceed the calculated frequency.
3
7.03125
(b) Subtract frequency represented by A
4
9.37500
5
11.71875
switch setting from calculated frequency.
6
14.06250
(c) Select highest B-switch setting which
7
16.40625
represents but does not exceed the frequency remainder
C ----------------
0
0
calculated in (b) above.
10.292969
(d) Subtract frequency represented by B-
2
0.685938
3
0.878906
switch setting from frequency represented by A-switch
4
1.171875
setting.
5
1.464844
(e) Select highest C-switch setting which
6
1.757813
represents but does not exceed the frequency remainder
7
2.050782
D ----------------
0
0
calculated in (d) above.
1
0.036621
(f) Repeat (d) and (e) above for each of
2
0.073242
the remaining thumbwheel switches in order, left to right.
3
0.109863
4
0.146484
5
0.183105
6
0.219726
3414.1"; the formula becomes F = (80.28668 cos
7
0.256347
3414.1") Hz.
3-7
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