POINTING ACCURACY/REPEATABILITY

• Document Type: CREST
• Collection: General CIA Records
• Document Number (FOIA) /ESDN (CREST): CIA-RDP88-01418R000200140004-3
• Release Decision: RIFPUB
• Original Classification: K
• Document Page Count: 3
• Document Creation Date: December 22, 2016
• Document Release Date: May 31, 2011
• Sequence Number: 4
• Content Type: MISC

Approved For Release 2011/05/31: CIA-RDP88-01418R000200140004-3
4.3.8 POINTING ACCURACY/REPEATABILITY (EST Test Time - 30 minutes;
requires down time)
Purpose
This test checks the pointing accuracy and repeatability of
the antenna control system.
Description
In this test, two or more satellites are acquired from four
different directions. The actual position data is then
compared to the predict data to determine pointing accuracy
and repeatability.
4.3.8.1 Set the Corrective Step Threshold (CST) parameter to "2" at
the ACU. (If the received signal is bouncy, this number may
be increased to allow the system to park). Position antenna
to two or more satellites whose position is known within 0.01
degrees versus time. (Attach a copy of the predict data to
the test procedure). Approach each satellite from four (4)
directions by manually driving off approximately 0.5db and
using steptrack to repeak the signal. Record data.
r
0 w. 9.(0 O
0
0
TIME
/: 7( GM 7
/?2 7 cT
3 ., Gi4rr
/.34 GMT
~.4D 6M7-
/.SS GMT
/.Sf e 1T
~.0/ GMT
/7 Ua -D
B. 3 c?4.3~9 ,_?Sr 0_-~3.1L & 0
O . l a4s, 9y ia.s O
0, / A - ? . O d
WANG ID. NO. 1873B
PREDICT SIGNAL ACTUAL DIFFERENCE
SATELLITE AZ EL .RTRENNGTI~F~ AZ EL AZ EL
F _ J4 9.40 0 a4 ?,GO --0j O
SIZE
A
CODE IDENT
33875
SCALE
DRAWING NO.
SHEET 25
Approved For Release 2011/05/31: CIA-RDP88-01418R000200140004-3
 Approved For Release 2011/05/31: CIA-RDP88-01418R000200140004-3
T
4.3.8.2 Use the DIFFERENCE figures to calculate the Beam Radial
Error. (BRE)
2
RMS AZ =1 (fin COS ELn) 9
o,OoXS3
Z
RMS EL n-X8 (ELn)2
1
Z.2
0
BRE = (RMSAZ)2+ (R$L)2
Pointing Accuracy = BRE =0.009s3 RMS
This pointing accuracy should be equal to or better than
the pointing accuracy obtained in the pre-modification test.
4.3.8.3 Use the DIFFERENCE figures to calculate the repeatability.
Calculate the mean of the four difference numbers for each
satellite.
SAT A F (o AZ mean 00 _ EL mean 0
SAT B F S AZ mean O EL mean 0
SAT C AZ mean EL mean
Calculate the deviation AZd and ELd from the mean for each
difference number for each satellite.
AZd ELd
SAT A S O
ooa,s ~
oo7S
, 0 ORS
-
WANG ID. NO. 1873B
SIZE
CODE IDENT
DRAWING NO.
A
SCALE
33875
82-30008-000
ISHEET 26
Approved For Release 2011/05/31: CIA-RDP88-01418R000200140004-3
 Approved For Release 2011/05/31: CIA-RDP88-01418R000200140004-3
SAT B
SAT C
RMS AZ = E2 (AZn COS ELn) 2
n=1
Use the deviation figure to calculate repeatability.
AZd ELd
Q
D 0
D a
V
RMS EL = nZ (ELn)2
Repeatability = (RMSAZ) 2 +(RMSEL)2
4.3.9 STEPTRACK TEST (EST Test Time - 2 hours; requires down time)
Purpose
This test demonstrates the ability of the antenna control
system to lock-on to a satellite signal, begin searching when
signal drops below a predetermined level and then lock-on once
again when signal level is restored. It also demonstrates the
system's ability to track a satellite for a period of one hour
dropping in and out of active track as required. The results
of the test are then analyzed statistically to obtain a value
for the tracking accuracy.
Description
Refer to Figure 4.
SIZE
CODE IDENT
DRAWING NO.
A
33875
WANG ID. NO. 1873B SCALE SHEET 27
77CS028
Approved For Release 2011/05/31 : CIA-RDP88-01418R000200140004-3