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ETL-09S1 

AD A1 00036 \ 

North-seeking gyrocompass 



Sperry Gyroscope 
Great Neck, N. Y. 11020 


JANUARY 1981 


n 


<r\\c 



APPROVED FOR PUBLIC RELEASE. DISTRIBUTION UNLIMITED 


Prepared for 

U.S. ARMY CORPS OF ENGINEERS 
ENGINEER TOPOGRAPHIC LABORATORIES 
FORT BUBLVOIR, VIRGINIA 22060 


mhhh 























Destroy this report when no longer needed. 

Do not return it to the originator. 

The findings in this report are not to be construed as an official 
Department of the Army position unless so designated by other 
authorized documents. 


The citation in this report of trade names of commercially available 
products does not constitute official endorsement or approval of the 
use of such products. 






SECURITyCLASSIFICATION OF THIS PAGE (Whan Bm Entered) _ 

( REPORT DOCUMENTATION PAGE befoI^comple^orm 

JF REJ’OR'r&VMBER |2. OOVT ACCESSION NO. *• RECIPIENT'S CATALOG NUMBER 

&)mo 25 Y 4d-a o3C _ 


1 4. TITLE fand Submit) 

^NORTH SEEKING GYROCOMPASS , 



S. TYPE OF REPORT * PERIOD COVERED 

Contract Report 


SOBMIMO ORB.-REPORT NUMBER 

SG-4223-1209/ 


LU RI RR OP OR BRA NT NUMBERf«J 


DAAK 70-78-C-O21O 


9. PERFORMING ORGANIZATION NAME AND ADDRESS 


SPERRY GYROSCOPE 
GREAT NECK, N.Y. 11020 


II. CONTROLLING OFFICE NAME AND AODRESS 


( V 

V ’ t. 





US ARMY 

ENGINEER TOPOGRAPHIC LABORATORIES 

FORT BELVOIR, VIRGINIA 22060_ 


MONITORING AGENCY NAME & AODRESS (II dlllertnl Iron Controlling Olllct) 15. SECURITY CLASS, (ol Olio report; 


IS. NUMBER OF PAGES 

84 


UNCLASSIFIED 


I5«. DECL ASSI FI CATION/DOWNGRADING 
SCHEDULE 


I*. DISTRIBUTION STATEMENT (ol thlt Report) 


Approve! for public release; distribution unlimited. 


17. DISTRIBUTION STATEMENT (of thm obotrmet onfrodl in Block 20, if dlfformt from Roport) 


i S' -*- 


1 %/ 



19. KEY WORDS (Contlnuo on rororoo oldo II ntcoetary and Idontlty by block number) 


NORTH SEEKING GYROCOMPASS 
NORTH FINDING MODULE 


20. ABSTRACT (Continue on rororoo oldo II nocoooory and Identity by block number) 

>IRIS REPORT DESCRIBES THE &0RTH SEEKING .GYROCOMPASS DELIVERED FOR EVALUATION 
ON THE Ml13 ARMORED VEHICLE. THE SYSTEircONSISTS OF A JJORTH JINDING MODULE 
ATTACHED TO A VEHICLE MOUNTED GtMBAL SET AND A SEPARATE'£ONTK0L PANEL7" 
BATTERY CHARGER. THE GYROCOMPASS SUPPLIES AZIMUTH TO AN"ACCURACY OF 2 MILS 
APPROXIMATELY 1 MINUTES AFTER TURN-ON. 

J. 


00 


:sr» 1473/ 


COITION OP I NOV Si IS ORSOLCTC 
8/N 0101*014* SS01 | 


UNCLASSIFIED j/ 

OCCUR! TV CL ABM PIC AT ION OP THIS PAB* 



















PREFACE 

This report describes the work effort and hardware manufactured 
under contract No. DAAK 70-78-C-0210 for US Army Engineer Topographic 
Laboratories, Fort Belvoir, Virginia by Sperry Gyroscope, an operating 
unit of the Sperry Division of Sperry Corporation, Great Neck, New York 11020. 
The Contracting Officer's Representative was Mr. Fred Gloeckler, Jr. 




1 










TABLE OF CONTENTS 


PAGE 


PREFACE 1 

ILLUSTRATIONS 3 

TABLES 3 

INTRODUCTION *+ 

INVESTIGATION * 

DISCUSSION 8 

CONCLUSIONS 27 

RECOMMENDATIONS 28 

APPENDIX A. NSG ALIGNMENT INSTRUCTIONS 29 

APPENDIX B. NORTH SEEKING GYROCOMPASS OPERATING 

AND MAINTENANCE MANUAL 33 

APPENDIX C. FACTORY ACCEPTANCE TEST PROCEDURE FOR 

ENGINEERING MODEL NFM 53 

APPENDIX D. ENVIRONMENTAL TEST SPECIFICATION FOR 

GIMBAL MOUNT 67 






LIST OF ILLUSTRATIONS 


Figure 

Title 

Page 

1 

NFM Mounted on NSG Gimbals 

6 

2 

NSG Family Tree 

9 

3 

NFM Mounted on MULE STTM 

10 

4 

NFM Front Panel 

12 

5 

Remote Signal Pulse Shape 

17 

6 

Output Signal Format and Timing 

18 

7 

NSG BB557 Battery Attached to Frame 

20 

8 

Vehicle Mount With Gimbal Assy 

22 

9 

Control Panel and Charger Schematic 

25 


LIST OF TABLES 



Table Tide Page 


1 

NSG Gimbal Data 

7 

2 

Data Summary 

7 


3 









INTRODUCTION 

The North Seeking Gyrocompass (NSG) developed for USAETL consists 
of a North Finding Module (NFM), as developed for the Naval Weapons 
Center (NWC), China Lake, California, attached to a vehicle mounted gimbal 
set. The NFM is a battery operated gyrocompass with a LED display that 
supplies azimuth (heading) information in 2 minutes to an accuracy of 
2 mils RMS. The NSG also includes a separable Control Panel/Charger 
which permits the NFM to be turned on remotely, locks the gimbal set and 
is used to charge the NSG battery. 

INVESTIGATION 

The design and development of the NSG consisted of two critical in¬ 
vestigations: 

a) Design investigation - This task consisted of layout studies to 

determine the best packaging approach to minimize size and weight. 

An important requirement was that the NFM used on the NSG would 
be unchanged from the design developed for NWC. The final design 
(see Figure 1 ) consisted of a standard NFM mounted to an inter¬ 

mediate support structure, the "frame”. The frame is removable 
from the gimbal system. It holds a BB557 Nickel-Cadmium battery 
which operates the NFM in off-vehicle applications. The frame is 
designed to mount directly onto the night-sight bracket on the 
GLLD*. Considerable effort was expended in order to provide desired- 
tilt freedom. The center of gravity and weights of components had 
to be carefully controlled in order to maintain a natural balance. 

The NFM has to be nominally level (+ 3A°) when mounted on the 
pendulous gimbal structure. The design investigation also included 

♦Ground Laser Locator Designator 


4 







the placement of viscous dampers on the gimbals. Damping was desired in order 
to quickly stabilize the NFM in a level position after vehicle motion stops, 
b) Gimbal Lock Investigation - On September 20, 1979 a series of tests 
were conducted on the M-113 with the first of two gimbal sets designed 
and built for the NSG. The purpose of this test series was to deter¬ 
mine whether any accuracy degradation occurred when the NFM was allowed 
to be free and pendulous while operating. (The concern was that gimbal 
movements induced by the NFM might in turn degrade NFM performance.) 

The data is presented in Tables 1 and 2. 

The results of these tests indicated that although the two-mil 
spec was met, NFM performance (0.5 mil) was degraded to 1.8 mil with 
the engines on and operating at rated idle (1000 RPM). With a very 
rought idle (about 400 RPM), caused by a malfunctioning idle adjust in the 
M-113, the NFM had a tendency to turn off before completing the north¬ 
ing run due to excess movement. When the gimbals were immobilized, 
this did not happen. 

As a result of this investigation, gimbal locks were added to 
both gimbal systems. These solenoid-controlled gimbal locks are 
activated remotely by means of a switch on the Control Panel and 
Charger Assembly. 











Figure 1. NFM Mounted on NSG Gimbals 


6 









TABLE 1. NSG GIMBAL DATA 


. rf„ — 



ENGINE RPM 


GIMBAL 




0 

400 

700 

1000 

FREE LOCKED 

AZIMUTH 

MEAN 

S.D, 

X 

X 




X 

X 


3949.7 

3949.7 

3949.67 

.05 

X 




X 


3949-6 



X 





X 

3949.1 



X 





X 

3949.3 

3948.53 

.38 

X 





X 

3948.6 



X 





X 

3949.1 



X 




X 


3948.2 



X 




X 


3947.3 

3947.8 

.37 

X 


X 


X 

X 

3947.9 

3948.7 





X 


X 


3948.1 





X 



X 

3948.3 





X 


X 


3947.9 





X 


X 


3948.3 




X 



X 


-15 * 




X 


X 

X 

X 

3948.1 

3947.4 






X 

X 

X 

X 


3951.9 

3950.9 

3949.24 

1.82 




X 

X 


3948.4 






X 

X 


3947.6 




X 



X 


-15 * 




X 



X 


-15 * 




X 



X 


-15 * 



X 


X 


X 

X 

3948.7 

3948.3 





X 



X 

3948.3 




X 



X 


-15 * 




TABLE 2. DATA SUMMARY 


NUMBER OF 


ENGINE 


GIMBAL 

MEAN 

S.D. 

NORTHINGS 

OFF 

400RPM 

400RPM 

FREE LOCKED 



7 

X 



X 

3948.73 

.9 

4 

X 



X 

39^8.53 

• 38 

5 


X 


X 

-15 ALARM* 


1 


X 


X 

3948.1 

— 

8 



X 

X 

3948.76 

1.47 

5 



X 

X 

3948.35 

.22 


# Denotes excess NFM Movement 


7 





DISCUSSION 


1. Equipment Description 

The NSG consists of two main components: 

1. The Mounted North-Seeking Module 

2. The Control Panel and Charger 

The North Seeking Module in turn consists of: 

1. North Finding Module 

2. Battery Assy 

3. Structure (Gimbal System) 

The Family Tree of the NSG is shown in Figure 2. 

2. North Finding Module 

The NFM is the sensor for the NSG. The Sperry North Finding 
Module is a pendulous gyrocompass used to determine true (geographic) 
north and grid azimuth. The NFM was designed specifically for the 
MULE (Modular Universal Laser Equipment) to be mounted on the STTM 
(Stabilized Target Tracking Module). Figure 3 shows the NFM mounted 
on the MULE STTM. 

The NFM meets all the requirements of the XAS 453&B Critical 
Item Development Specification for North Finding Module and the North 
Finding Module ICD (Interface Control Document) 2969* 

The Sperry NFM has been designed to fulfill a number of missions 
requiring medium to high azimuth accuracy. The trade-offs are between 
accuracy, time and the need for pre-alignment. For applications such 
as FIST and MULE the requirement is an accuracy of 2 mils RMS in 2 
minutes of time with no pre-alignment and with up to mis-level. 

For survey type of applications, up to 15 minutes of time may be 
acceptable for a northing, with approximate pre-alienment (+ 10°1 to 
north, a 10 to 1 improvement in accuracy is possible (i.e. 0.2 mils 






NORTH¬ 

SEEKING 



Figure 2. NSG Family Tree 















1 









RMS). When the NFM can be pre-levelled within 3 minutes of arc, an 
azimuth error of less than 2 mils RMS can be achieved within one 
minute of time. Recognizing that no single mission can afford the 
starting costs associated with dedicated hardware, Sperry designed 
the NFM to meet these multi-mission requirements with common hardware, 
modifying software to meet the mission requirements. 

NFM versatility is derived in large part from the exploitation 
of state-of-the-art microprocessor technology combined with the de¬ 
pendable and proven gyrocompass. True azimuth is obtained from this 
sensor. Grid convergence, as given on UTM maps, can be inserted and 
stored in non-volatile memory so that grid azimuth can also be dis¬ 
played. With this capability, grid convergence (or northing and east¬ 
ing data) can be a pre-mission insertion requiring no further mission 
procedures. 

Operation of the NFM is initiated from the front panel, shown 
in Figure 4, or by remote turn—on. The front panel consists of a LED 
play, the five-position MODE switch, and a pressure-activated toggle 
DISPLAY/SLEW switch. 

These two control panel mounted switches initiate the following 
functions: 

MODE SWITCH 

POSITION FUNCTION NAME 

1 OFF 

2 ON 

3 GRID CONV 

4 EAST 


5 


NORTH 








Figure 4. NFM Front Panel 

















DISPLAY/SLEW SWITCH 



1 -TRUE (True Azimuth) 

2 +GRID (Grid Azimuth) 

The NFM connector to which power is applied is also the means 
by which functions can be remotely initiated. A full explanation of 
the remote display capability is found on page 16. The functions 
on the NFM connector are tabulated below. 


CONNECTOR PIN 
PIN NO. 

A 

B 

C 

D 

E 

F 

H 


FUNCTION NAME 
CLOCK (10V) 

CLEAR/DATA ENABLE (10V) 
SERIAL DATA (10V) 

SEND DATA (20- 36 V, 40 Ma) 

FIND NORTH (20-3*V, hO MA) 

PRIMARY POWER (+1Q to +31 VDC) 

POWER/SIGNAL RETURN AND CASE GND 


There are two light emitting diodes (LED) on the front panel, 

ALARM and ACTIVE. Since the NFM employs continuous built-in test, 
the ALARM LED is illuminated in the event of a malfunction. The ACTIVE 
LED is illuminated when the NFM is performing its gyrocompass function 
to determine azimuth. This serves as a visual indication to the 
operator that the NFM should not be physically disturbed or mode switched. 
When this LED turns off, the NFM is available for information call-up 
01 mode change. 

Keys consisting of four digit numbers are inserted by the proper 
sequencing of the MODE switch and the DISPLAY/SLEW switch. These 
keys convert the NFM from a tactical MULE application to a survey, 
vehicle, or factory test application. The non-volatile memory will 


13 




retain the value of key set, even after power to the NFM is removed. 

Changes in the MODE switch from OFF to any other position will 
initiate the mode requested. Change from any position to any other 
position but OFF will initiate the new mode requested after comple¬ 
tion of the mode in progress, provided the NFM has not yet entered 
the power-down phase. The NFM will power down automatically to zero 
power when its operational mode is completed. Insertion of data is 
by means of the INPUT modes on the MODE switch (GRID, CONV, EAST or 
NORTH) and the DISPLAY/SLEW switch. Values can be most quickly 
entered by inserting the most significant digit first. Holding the 
DISPLAY/SLEW switch to + will cause the display to cycle through all 
10 ones digits in an increasing direction} then all 10 tens digits; 
then all 10 hundreds digits and finally to the thousands digits. Re¬ 
lease the DISPLAY/SLEW switch at the desired most significant digit. 
Reoeat the above, releasing at the next significant digit. Continue 
until the correct total value has been inserted. Holding the DISPLAY/ 
SLEW switch to - will have the same effect except in a decreasing 
direction. 

The simplest operating mission of the NFM is the MULE mission. 
During this mission the operator need only turn the MODE switch from 
OFF to ON. At the conclusion of its two-minute cycle, the ACTIVE light 
will extinguish. Toggling the DISPLAY/SLEW switch to TRUE will 
cause heading to true north to be displayed for 5 seconds. 

To determine azimuth with respect to grid north, place a grid 
convergence value into the NFM either by direct insertion of grid 
convergence or by allowing the NFM to calculate grid convergence from 
inserted map values of UTM easting and northing. These values are 
stored in non-volatile memory, thus allowing the forward observer to 


14 





insert these values prior to to the start of the mission. A calcu¬ 
lated value of grid convergence is distinguished from an inserted 
value by the fact that the display blinks for the former. Turn the 
MODE switch from OFF to ON. When the ACTIVE light goes out, the NFM 
has calculated and stored grid azimuth within it, which will be dis¬ 
played for 5 seconds when toggling the DISPLAY/SLEW switch to GRID. 
Toggling to TRUE will give true heading as before. 

Midway through a northing (approximately 60 seconds) the ACTIVE 
LED will blink several times. At this time a preliminary indication 
of heading can be called up. Accuracy of this value is dependent 
upon leveling accuracy. 

Polar operation (above 66.5° Lat N or S) will be selected 
automatically with the insertion of the correct northing value. 

Although not recommended for tactical operation, a key can be 
inserted into the NFM to energize the display automatically at the 
end of the northing cycle. If the key is inserted, t/ne NFM obviously 
will not pass the 75 ft. dark tunnel test. 

Automatic bump detection is included to discount the effects of 
accidental movement of the tripod or support structure during the 
operating cycle. This is accomplished by comparing the integration 
cycles at each internal position of the gyro. If the difference exceeds 
a pre-set amount, the integration is repeated. 

For normal MULE operation under tactical conditions, the display 
alarm key is not set. The presence of an alarm will be indicated by 
a four second lighting of the alarm LED. No azimuth information will 
be displayed. 







A _t 


NFM Remote Data Interface 

The NFM has the capability for remote activation and will 
transmit a serial data signal representing true north. The remote 
data interface is accomplished by disconnecting the NSG power connector 
harness on the NFM and replacing it with a Viking Industries VR7/4AG19 
connector on an Output Interface Cable. The Output Interface Cable 
can be up to 1000 feet long. 

Electrical interconnections are given on page 13. 

The two input signals associated with remote operation are 
"Find North" which permits the user to remotely reactivate the unit and 
initiate a north finding cycle, and "Send Data" which transmits data. 

Send Data and Find North signals will only be recognized when the unit 
is powered down and the MODE switch is in the ON position. The pulse shape 
for these signals is given in Figure 5 . 

The output signals consist of: 

1. Start output which indicates the start of the serial 
output operation. It occurs before the start of trans¬ 
mission of the sync pulses and the data bits. 

2. Eighteen serial data bits, consisting of a data valid bit, 
sixteen data bits, and a parity bit. The data bits are 
transmitted synchronously with the serial output sync pulses. 

3. Eighteen serial output sync pulses corresponding to the 
eighteen serial data bits. Each sync pulse occurs within 
a data bit. These pulses are utilized as "read data bit" 
commands. 


16 






Output signal format and timing are given in Figure 6. 
Output Signals Electrical Parameters 

Pulse Duration: Various - See Figure 6 

Pulse Amplitude: +10V (+1V-2V) 

Output Source Current: 1 ma 

Pulse Rise Time: 3 microseconds 

Pulse Fall Time: 3 microseconds 



t f <100 MICROSECONDS 
t f <100 MICROSECONDS 


Figure S. Remote Signal Pulse Shape 







Figure 6. Output Signal Format and Timing 





f 

r 


3. Battery Assembly 

The battery assembly selected for the NSG mission is the BB 557 
rechargeable nickel-cadmium battery pack. This standard 24 volt mili¬ 
tary battery has a rating of .45 ampere-hours and can provide up to 
30 northings on one charge. The NSG is designed to operate either on 
the vehicle b&utery or the BB 557* When the NFM and frame are dis¬ 
connected from the gimbals, the NFM is automatically switched to the 
BB 557 battery. It is used for off-vehicle applications and for use 
on the GLLD night sight bracket. The NFM battery is automatically 
charged when the NSG is connected to the vehicle battery. 

The BB 557 battery is readily accessible and can be replaced 
without difficulty. (See Figure 7.) 

4. Structure 

The basic structure of the NSG consists of the frame and the 
gimbal assembly. The frame serves several functions: 

(1) It is the intermediate structure to which the NFM is fastened. 

(2) The BB 557 battery is secured to the frame. 

( 3 ) The frame holds the relay that automatically switches NFM 
power from the vehicle battery to the NSG battery when vehicle 
power is disconnected. 

(4) The frame is separable from the gimbal structure, it provides 
the interface to secure the NFM to the GLLD night sight bracket. 

(5) The frame provides the pendulosity required to level the NFM. 

The gimbal assembly provides the angular freedom required for 

on-vehicle applications. The NFM is able to perform within specifi¬ 
cation when misleveled up to £°. A 50% reduction in accuracy may 
occur when the NFM is misleveled further (up to 0.6°). The gimbals 


19 








Figure 7. 


NSG BB-557 Battery Attached to Frame 







are designed to maintain the NFM in an acceptable level condition 
when the vehicle is tilted. They provide for up to + 15°freedom in 
pitch,+10° freedom in roll when the NSG is mounted to the side walls 
of a vehicle. The NFM/battery/frame assembly is pendulous. The 
pendulosity provides the force necessary to overcome bearing friction 
and maintain the NFM level. Viscous dampers are included on each 
axis. The dampers use a high viscosity silicone fluid in a .010 inch 
gap. The viscous shear action quickly settles gimbal motion after 
the vehicle has stopped. 

Solenoid activated gimbal locks have also been included (see 
Investigations). The purpose of having gimbal locks is to prevent 
small settling motions in the gimbals during an NFM operating cycle. 
The gimbal locks are activated remotely by a switch on the control 
panel/charger assembly. The gimbal locks are not intended to hold 
the gimbals during vehicle operation. They should be engaged only 
after the vehicle has stopped and the gimbals are motionless. 

5. Vehicle Mount 

The NSG module is secured to the vehicle by an intermediate 
support plate. This plate includes a hinged lock screw that can be 
used to immobilize the gimbals during normal vehicle operation. The 
screw must be unlocked for normal NSG operation so that the NFM is 
level. (See Figure 8.) 

6. Control Panel and Charger 

The control panel and charger (CP/C) was designed and built 
specifically for the NSG application. It provides the electrical 
interface between the vehicle battery and the NFM. It is used to 
charge the NSG battery, but it serves other useful functions. It 
monitors the vehicle battery and disconnects that battery when 


21 






Figure 8. Vehicle Mount with Gimbal Assembly 




22 












.. a -- 


i 

its voltage drops below prescribed limits (19.? volts DC). This ! 

prevents a condition in which the vehicle battery would become a 

load on the NSC battery. The CP/C has a booster circuit which 

charges the °HV NSG battery even when the vehicle battery voltage 

is down to ^0 volts. The schematic of the CP/C is shown in 

Figure 9. 

The CP/C can he located anywhere in the vehicle. After the MFM 
is turned on, the CP/C can be used to initialize a northing by pressing 
the FIND NORTH toggle switch. At the end of the northing cycle, the 
NFM display will be reawazened by pressing the SEND DATA switch. It 
is recommended that the GIMRAL LOCK switch be turned ON before the 
NFM is energized. That will assure more accurate heading data. 

The CP/C is supplied with a 12-foot cable to connect to the 
vehicle battery. A 10-foot cable is supplied between the CP/C and 
the gimbal assembly. The NSG can therefore be activated when the 
operator is out of the vehicle or almost anywhere in the vehicle. 

7. Calibration and Alignment 

The NSG output is the azimuth of the NFM mounting surface relative 
to true (geographic) north. In order to align the NFM to the vehicle 
axis, an Alignment Fixture (AF) has been provided. The alignment 
method is detailed in Appendix A. The AF contains a poro prism and 
is calibrated for three angular positions: 

1) normal to the NFM mounting surface 

2) 60° to the left of the mounting surface 

3) 60 ° to the right of the moiinting surface. j 

This makes it possible to optically align the NSG to the 

i 

vehicle axis when the NSG is positioned on any vertical surface of 
the Mill vehicle. 


23 






T 

r 




3 


k 


Complete operating and maintenance instructions have been 
prepared in a manual which is included in Appendix B. The 
acceptance test requirements for the NFM are presented in Appendix C. 
The environmental test specification for the NSG gimbal system is 
presented in Appendix D. 


24 























e>e>ss7 


V* ^ 

T Vl 



Figure 9. Control Panel and 
Charger Schematic Diagram 


25/26 


FP 



CONCLUSIONS 

1. The NSG was designed to satisfy a variety of missions utilizing the 
MULE NFM as the sensor. 

2. The design of the NSG permits the NFM to be utilized on the Ml 13 (or 
other vehicle) as well as on a GLLD tripod. 

3. The NSG has mission capability using either a vehicle battery or its 
own rechargeable military battery. 









X, 


RECOMMENDATIONS 

1. The NSG was designed to mount on a vehicle, but it does not have 
a remote display . It is recommended that a remote display unit 
be designed for the NSG which would be placed in the driver's com¬ 
partment. The simplest readout would be a LED display that would 
repeat the NFM outputs. A more desirable readout would entail the 
use of a compass card or similar visual display. This would require 
that the NFM digital serial outputs be converted to an analog 
signal. The analog signal would, in turn, be used to drive a servo 
motor attached to a compass card. 

2. By including a resolver or an accelerometer on each axis of the gim- 
bal assembly (depending on the desired accuracy), the NSG can be used 
to provide pitch and roll information. 


t 






APPENDIX A 


NSG ALIGNMENT INSTRUCTIONS 






ENGINEERING 

SPECIFICATION 


GREAT NECK, N. V. 11020 


SECURITY NOTATION 


REV 

SYM 


10 H 


15 — 


20 


25 H 


30H 


46 H 


The NFM Alignment Fixture (AF) consists of a poro prism mounted on NFM alignment 
pads. The AF is mounted in place of the NFM and is used to align the FIST gimbal 
pads. For versatility, the fixture can be locked into three pre-calibrated 
positions. The position of the prism ir changed by pulling down fully on the 
Positioning Plunger (see attached Figure 1), grasping the sides of the prism holder 
and rotating to the desired position. When the plunger is released it engages 
and locks into position. The available positions are: 

1. Normal to the NFM Mounting Surface 

2. 1070.8 MILS Clockwise 

3- 1071.3 MILS Counter Clockwise 

The orientation is as shown in Figure 2. 

When the AF is mounted in the gimbal system the gimbals must be balanced so that 
the mounting pads are in a vertical plane. The AF is provided with a bubble level. 
The assembly is adequately leveled when the bubble remains inside the marking ring. 
Balance the assembly by loosening the Frame Locking Screw and sliding the frame 
forward until the bubble is centered. If the assembly requires weight on the left, 
a special Balance Nut is provided. Press in the Night Sight Mounting Screw Knob 
and engage the nut until the desired balance is achieved. 


SECURITY NOTATION 



CODE IDENT. NO, 

SPEC NO. 

REV 


56232 

1 $ - /£29 g 3 

- 



SHEET £ j 


FORM633114A 11 2155 


30 









• 31 


FORM 633114A 11 2186 









)r 


ENGINEERING 

SPECIFICATION 


SECURITY NOTATION 


GREAT NECK, N. Y. 11020 


NFM - F/ST *LHA/MfA/r OAtj&ATWAS 

(AtL Vi€Wo 1.00*1*6 bOuJ* 0* NFH ) 


WFFf hoourtt/l, zudF^tr ^ ] 



ct\>j posrrtOA/ 


Ficu/ze 2. 


rtothAL TO Hi* *06 


I OH. I Hl/LS, 


■ vo*mai ro 
HT(, iofiFAce 


L — (utFACf 

SusSie -— 
Mwm(, 


C-Oj PO& fj/OA/ 


f+*fm n m**h 



f07 

-*-1 SvdFA C.X 


Stf *FHC* 


SECURITY NOTATION 


• 0* Poi/nw n a To Moovrit/c* sotPAcf. 

• CAuinr/i*/ 4*4 fifpf*rA 8 /ury ojtrttfis ±o.$ m/c& . 


TATION: CODE IDENT. NO. EPIC NO. 

56232 ¥LlS'tt*1*3 


FORM 633114A II 3166 











APPENDIX B 

NORTH SEEKING GYROCOMPASS 
OPERATING & MAINTENANCE MANUAL 


i 










1.0 DESCRIPTION 

1.1 GENERAL 

The North Seeking Gyrocompass (NSG) provides an azimuth reference 
for the FIST vehicle, a dismounted Ground Laser Locating Device (GLLD), 

and a GLLD in its alternate vehicle mount. 

\ 

1.2 DESCRIPTION OF EQUIPMENT 

The NSG is a North Finding Module (NFM), gimbal mounted for self¬ 
levelling which has the capability to rapidly find and display grid or true 
azimuth. It consists of the NFM which, with a self-contained battery, can 
be eit her ve hicle or externally mounted. The vehicle complement consists 
of the gimbals and the control panel and battery charger. An exploded view 
is shown in figure 1-1. (The control panel and charger are shown in 
figure 1-2). 


34 





























r 




I 


2.0 INSTALLATION 

2.1 FIST VEHICLE USE 

The NSG unit shown in figure 1-1 is mounted to a bulk head in the 
FIST vehicle. The unit, as a pendulous device, levels itself for use. When 

not in use the NSG is secured via the traveling eager. 

2.2 DISMOUNTED GLLD USE 

Separating the NSG at the pitch axis allows the use of the North 
Finding Module with a GLLD. 

The mount is designed to attach to a GLLD in place of the Night 

Sight. The battery is included as part of the mount so as to not require 

external power. 


f 

i 


37 






OPERATION 

PHYSICAL DESCRIPTION 


NSG versatility is derived in large part from the exploitation 
of state-of-the-art microprocessor technology in conjunction with the 
tried and true gyrocompass. From this sensor, true azimuth is obtained. 
Grid Convergence, as given on UTM maps, can be inserted so that grid 
azimuth can also be obtained. 

Operation of the NSG is initiated from the front panel or by 
remote turn-on at the control panel. The front panel consists of a LED 
display, the five position MODE switch, and a spring-loaded return to 
center DISPLAY/SLEW switch. 

These two front panel mounted switches initiate the following 
functions: 


MODE SWITCH 


Position 

1 

2 

3 

4 

5 

DISPLAY/SLEW SWITCH 
1 
2 


Function Name 
OFF 
ON 

GRID CONV 

EAST 

NORTH 

-TRUE 

(not named) 


3 +GRID 

The control panel consists of two switches, an on-off switch 
and a mode switch. The on-off switch disconnects M—113 battery power from 
the NFM. The MODE switch initiates a northing cycle in the FIND NORTH 

position and displays the previously measured TRUE heading in the SEND 
DATA position. 


38 







A. 


Changes in the MODE SWITCH from OFF to any other position 
will initiate the mode requested. Change from any position to any 
other position but 'OFF' will initiate the new mode requested after 
completion of the task in progress, provided the NFM has not yet 
entered the POWER DOWN phase. The NSG will POWER DOWN automatically 
when its task is completed. The NSG can be started (from POWER DOWN) 
(in order of precedence) by requesting SEND DATA or FIND NORTH via 
the control panel. These requests will only be honored while the 
NSG is in the POWER DOWN phase. 

There are two micro lights on the front panel, ALARM and 
ACTIVE. Since the NSG employs continuous built-in test, the ALARM 
is illuminated in the event of malfunction. Section 4 gives the 
alarm codes and the procedure to be followed in the event ALARM is 
illuminated. 

The second micro light is illuminated when the NFM is per¬ 
forming its gyrocompass for the determination of azimuth (OQO sec). 
This serves as a visual indication to the operator that the NSG should 
not be physically disturbed or mode switched. When this light is 
extinguished, the NSG is available for information call-up or mode 
change. 

A North finding cycle is initiated by sending a FIND NORTH 
signal to the NSG. At the conclusion of the cycle, TRUE NORTH will 
be transmitted via the output data channel. The NSG can be reactivated 
for data retrieval by sending a SEND DATA signal to the NSG. The True 
North previously obtained will be redisplayed. The NSG mode switch 
must be in any position but OFF (only True North will be displayed). 


39 




f 


K» 


A... _i.... 


3.2 OPERATIONAL PROCEDURE IN FIST VEHICLE 

The following is a step by step operational procedure to be 
used for operation of the NSG in a tactical environment. It is 
assumed that the NSG was leveled and power applied to the unit. It is 
further assumed that no Grid Convergence is stored in the NSG at this 
time. 

3.2.1 AZIMUTH DETERMINATION WITH RESPECT TO TRUE NORTH 

1) Toggle Control Switch to FIND NORTH. 

2) When active light goes out (080 sec.) the NSG has calculated 
and stored within it true heading which will be displayed for 
5 seconds when "toggling" the control switch to the SEND DATA 
position. 

COMMENTS: 

a) SEND DATA can be performed as many times as desired as long 
as the NFM MODE switch is in the ON position and is not 
turned to OFF. 

3.2.2 AZIMUTH DETERMINATION WITH RESPECT TO GRID NORTH 

1) Place a Grid Convergence into NFM either by direct insertion 
of Grid Convergence (Section 3.2.2.1) or by allowing NFM to 
calculate Grid Convergence using grid coordinates (Section 
3.2.2.2). Allow the NSG to level itself. 

2) Toggle Cont-il Switch to FIND NORTH. 

3) When active light goes out ( K. 180 sec), the NSG has calculated 


and stored within it grid azimuth which will be displayed for 5 
seconds when the DISPLAY/SLEW Swtich is toggled to the right 
(GRID position). 



I 


T 


COMMENTS: 

a) DISPLAY/SLEW cAh be performed as many times as desired as 
long as the NFM MODE switch is in the ON position and is not 
turned to OFF. 

b) Switching the DISPLAY/SLEW switch to TRUE will give heading 
values differing from the GRID values by the amount of the 
Grid Convergence 

c) If the Control switch is toggled to SEND DATA True Azimuth 
will be displayed. 

3*2.2.1 INSERTION OF GRID CONVERGENCE 

1) Set MODE switch to GRID CONV. 

2) Slew desired value in by holding the DISPLAY/SLEW switch until 
desired value is reached. 

3 ) Allow unit to Power down. 

4) Place MODE Switch to the ON position. 

COMMENTS: 

a) Values can be best inserted left most digit first. Holding 
the DISPLAY/SLEW switch to + will cause the display to cycle 
through all ten ones digits in an increasing direction; then all 
ten tens digits; then all ten hundreds digits and finally to the 
thousands digits. Release the DISPLAY/SLEW at the desired left 
most digit. 

Repeat the above releasing at the next digit. Combine until the 

correct total value has been inserted. Holding the DISPLAY/SLEW 

switch to - will have the same effect except in the decreasing direction. 


b) This value of Grid Convergence will remain stored in the NSU 
until changed, even if the NSG is turned off. 



3.2.2.2 


GRID CONVERGENCE CALCULATION 

NSG accuracy is such that a major source of error may be the 
Grid Convergence available (to the nearest mil on most military maps) 
for insertion into the NSG. In order to eliminate this error 
source, the NSG has the capability of calculating Grid Convergence 
directly from position data and then utilizing this value for heading 
determination. 

GRID CONVERGENCE CALCULATION PROCEDURE 

1) Set MODE switch to EAST 

2) Slew in the Easting value as determined from the UTM map. 

This value should be the whole kilometer East of the 

NFM location. 

3 ) Set MODE switch to NORTH. 

4) Slew in Northing value as determined from the UTM map. This 
value should be the whole kilometer South of the NFM location. 

5) Allow unit to Power down. 

6 ) Return MODE switch to ON position for normal operation. 

COMMENTS: 

a) Eastings are never negative and are always in the range 110 Km. 

55 E ^ 890 Km. Northings are positive in the northern 

hemisphere and negative in the southern hemisphere. In the 
northern hemisphere the range from 0° to 80 ° latitude is 0 to 
+ 8900 Km. In the southern hemisphere 0° to 80° Latitude is 
the range -9999 Km to -1100 Km. 

b) The value of Grid Convergence will remain stored in the NFM 


through the OFF position and until changed, either by the 
method of 3*2.2.1 or the method of this sub-section. 







POLAR OPERATIONS 



3-2.3 

For operation above the latitudes of 66.5°, the NSG requires 
300 sec to determine azimuth. To place the NSG into this mode a 
northing value, corresponding to the latitude of operation must be 
inserted. 

POLAR MODE OPERATIO N 

1) Set MODE switch to North 

2) Slew in northing value corresponding to the latitude of operation. 

3) Allow unit to power down 

4) Return MODE switch to ON position and allow NSG to level itself. 

5) Toggle Control Switch to FIND NORTH. 

6 ) When ACTIVE light goes out (5 min), the heading information is 
stored in the NFM. It will be displayed for 5 seconds by toggling 
the control switch to the SEND DATA position. 

COMMENTS: 

a) The NFM will perform a polar mode determination for any 
northing greater than +7375 Km or in the range -2621 Km to -1 Km. 

b ) If Grid North is desired, Easting must be entered as well as 
Northing and the front panel DISPLAI/SLEW switch must be 
toggled to the GRID position when the ACTIVE light goes out. 



43 








OPERATIONAL PROCEDURE FOR USE WITH A DISMOUNTED GROUND LASER LOCATING 

DEVICE (GLLD) 

To operate the North Finding Module (NFM) with a dismounted GLLD, 
it is necessary to separate the North Seeking Module (SSM), (the GLLD 
tripod mount with the NFM and battery) from the rest of the NSG. A thumb 
screw at the top of the NSM is loosened, allowing the removal of the 
NSM from the NSG. The cable from the gimbal mount also must be dis¬ 
connected. 

The NSM can then be attached to the GLLD in place of 
the night sight. The NSG battery provides power for NSM operation. 

The following is a step by step procedure for the operation 
of the NSM mounted to a GLLD. It is assumed that the unit is leveled 
and no Grid Convergence is stored in the NFM at this time. 


44 





1 


3-3.1 



i 

AZIMUTH DETERMINATION VITH RESPECT TO TRUE NORTH 

1) Turn MODE switch from OFF to ON. 

2) When active light goes out (< 180 sec.), the NSM has calculated 
and stored within it true heading which will be displayed for 

5 seconds when "toggling" the DISPLAY/SLEW switch to the left 
(TRUE position). 

COMMENTS: 

a) DISPLAY/SLEW can be performed as many times as desired as 

long as the NSM MODE switch is in the ON position and is I 

i i 

not turned to OFF. 

b) Switching the DISPLAY/SLEW switch to GRID will give heading 
values identical to TRUE since no value of Grid Convergence 
has been inputted and stored or calculated as yet. 


45 







AZIMUTH DETERMINATION WITH RESPECT TO GRID NORTH 

1) Place a Grid Convergence into NSM either by direct 
insertion of Grid Convergence (Section 3*2.2.1) or by 
allowing NFM to calculate Grid Convergence using grid 
coordinates (Section 3«2.2.2). 

2) Turn MODE switch from OFF to ON. 

3) When active light goes out (<l80 sec), the NSM has calculated 
and stored within it grid azimuth which will be displayed for 
5 seconds when "toggling" the DISPLAY/SLEW switch to the 
right (GRID position). 


COMMENTS; 

a) DISPLAY/SLEW can be performed as many times as desired as 
long as the NFM MODE switch is in the ON position and is 
not turned to OFF. 

b) Switching the DISPLAY/SLEW switch to TRUE will give heading 
values differing from the GRID values by the amount of the 
Grid Convergence. 






r - . 


3.4 CONCLUSION 

Adherence to the step-by-step procedure will insure that the NFM 
is setup for automatic operation and outputting of data. If the area 
of reference changes; i.e., a different UTM map or a different portion 
of the same UTM map, the Grid Convergence stored in the NFM must be 
changed to the new value of grid convergence. 


47 




TROUBLESHOOTING 


The MTBF of the NSG is such that normally no troubleshooting 
or repair will be done at the organizational level. The NSG 
employs an automatic Built-In-Test (BIT) routine which will key the 
ALARM indicator to illuminate when the DISPLAY switch is toggled. 

This alarm indicator will be energized for 4 seconds and then be 
extinguished. The alarm will be energized for any of the malfunctions 
listed in Table 4-1. (Since a number of these alarms are human or 
procedural errors, it is recommended that the operator key these 
alarm codes for corrective actions which he may employ before 
replacing the NFM). These alarm codes are keyed by turning the Mode 
switch to GRID CONV and slewing in the number 9999* After 12 seconds 
the 9999 indicator is extinguished and the NFM powered down. Re¬ 
peating the mode which gave the original alarm indicator, if the 
cause of the alarm still exists, the display will indicate the 
ALARM light and the alarm code. 

















i 

PARTS LIST 

The family tree of the NSG given in Figure 6-1 presents the 
Parts List for the equipment. 






NORTH- 

SEEKING 

GYROCOMPASS 



FAMILY TREE 














APPENDIX C 

FACTORY ACCEPTANCE TEST PROCEDURE 
FOR ENGINEERING MODEL NFM 



53 













A. 


m 




ENGINEERING 

SPECIFICATION 


REV 

SYM 






r^v 


Z -,- 

I SECURITY NOTATION 


GREAT NECK. N. Y. 11020 


3.1.2 Description of Tests 

NIX Functional Performance 
NFM Repeatability 
NFM Accuracy 
NFM Mis-level Accuracy 


3*2 Size and Weight 

3*2.1 Size - Measure the NIX to assure that the nominal dimensions conform to 
the Outline Drawing shown in Fig. 3 of the ICD. 


3.2.2 Weight - Weigh the NFM. Its weight shall be less than 4.0 lbs. 

3*3 Inspection 

Inspect the NFM to verify that there are no external adjustments 
visible or available and to locate the following controls and displays. 

3-3-1 Mode Switch - (5-position rotary switch with positions for OFF, ON, 
GRID CONV, EAST, and NORTH. 

3.3.2 DISPLAY/SLEW - Toggle Switch (RIGHT, Left, spring return-to-center) 

3.3.3 MILS Numeric Display - (4 digit) 

3.4 Test Set-up 

The test set-up for accuracy measurements consists of an indexing 


table aligned to true north, checked optically quarterly by star reference. 
Electrically, the test set up is shown in Figure 1. Mechanically, the 
test set-up conforms to the mounting pad arrangement shown in Figures 1, 2, 
and 4 of the ICD. 



S RlTY NOTATION. 

CODE iDr NT. NO. 

SPEC NO. 

RL v 


56232 

4223-139337 

E 



SHEET 3 Of 1), 


FORM 14A 11 ;ib1 


55 





ENGINEERING 

SPECIFICATION 


- -isr-i 


SECURITY NOTATION 


GREAT NECK. N. Y. 11020 


NFM Functional Performance 

This series of tests verify that the NFM performs functionally as required 
by the XAS 4536 8 specification. Operation of the NFM will be via the front 
panel of the NFM. Data insertion and NFM operation on this data will be test- 


3-5.2 


Set Up 

Mount the NFM to the index table utilizing the NFM mounting bracket. Attach 
the interconnecting cable to the interface connector, located at the top of 
the NFM. Verify ease of mounting. Set the DC power supply output voltage 
to 24 VDC, + 1 VDC. Set the Remote Display Unit to MILS 

Cycle Time. 


With the NFM mounted on the indexing table, operate the NFM in the ON position 
of tne MODE switch. Verify that the ACTIVE light is extinguished in less than 
120 seconds and that the Remote Display Unit reads out a value of azimuth at 
the same time that the ACTIVE light is extinguished. (In later tests the 
activation of the Remote Display Unit will constitute the time the NFM 
requires to find North). Toggle the Display/slew to TRUE. Record the data 
presented on the Remote Display Unit and the NFM display. The difference 
shall be <- 0.5 Mils. 

Insertion of Grid Convergence 

Turn the MODE Switch to GRID CONV. Verify that the display increases when 
the DISPLA1/SLF1V is set to + and decreases when the Switch is set to - 
Set the value of the display to +11. Allow system to Power Down. Turn the 
MODE Switch to OFF end then to ON. 


,TY NOTATION 


COOt lOLM. NO SPEC NO 


56232 4223-188337 




I SHEET u of 1 4 









engineering 

SPECIFICATION 


REV 

SVM 



X 


SECURITY NOTATION 


GREAT NECK. N. Y. 11030 


When the ACTIVE light is extinguished read out and record the display when 
toggling the DISPLAT/SLEW switch to TRUE. Read out and record the display 
when toggling the DISPLAY/SLEW switch to GRID. The difference of the two 
readings shall be 11 MILS. Record difference. Turn the RDU off and then ON. 
Activate the SEND DATA SWITCH. Verify that the NFM and the RDD ie-display 
the same value. Turn the MODE switch to OFF. Turn the MODE switch to GRID 
CONV. Verify that the display reads 11 MILS. Turn the MODE switch to OFF. 

3*5 A Calculation of Grid Convergence 

Turn the MODE switch to EAST. Insert 636 KM EASTING. Turn the MODE switch 
to NORTH. Insert 4*73 KM NORTHING. Turn the MODE switch to GRID CONV. Verify 




20 H 


3.5.5 


30 H 


3.6 


3s-T 


J 


3 . 6.1 

Ci IY NOTATION: 


that the calculated Grid Convergence is 21 MILS. 

Alarms 

Mis-level the NFM by greater than two degrees. Turn the MODE switch to ON. 
When the active light extinguishes, verify that the ALARM lights when the 
DISPLAY/SLEW switch is toggled. Verify that no azimuth is displayed. Turn 
the MODE switch to OFF. 

NFM Time, Accuracy, and Mis-Level 

This series of tests verify that the NFM performs within specification for 
time; accuracy and when in a mis-level condition as required by the XAS 4536 b 
specification. The Remote Display Unit will be used for all time and data 
readouts, with time measured from turn-on to when the display appears (it 
was verified previously that the NFM cycle was completed concurrent with the 
appearance of the display. 

Accuracy 

Align the NTT reference surface to 0 MILS North azimuth within +1/3 Mil, 


I CODE li>F.\T. NO. 

I 56232 


SPEC NO. 

4273-1 BPS 37 


fitv 

R 


r 


5 of 


14 


4 

I 








i 


ENGINEERING 

SPECIFICATION 



10 -H 


3 . 6.2 


20 H 


3-6.3 
3.6.3.1 


35- 



k __ 

5 SECURITY NOTATION 


GREAT NECK, N. V. 11020 


utilizing the indexing table. Record indexing table heading corresponding 
to True North. Set the NFM Mode switch to the ON position. After the 
ACTIVE LED is extinguished, record output reading of the RDTJ in measured 
data column. If reading is 63 XX, subtract 6*400 and record difference in 
calculated data column. For readings of OOXX enter same number in both 
measured and calculated data columns. Repeat this cycle seven times, 
using the FIND North switch in the test set up. Record RDU readings. 
Calculate the mean and standard deviation of the eight calculated data. The 
repeatability of the system is the standard deviation of the data from the 
mean value. This standard deviation shall be — 1 mil. 

Turntable Accuracy and Time-to-True North 

NFM accuracy is verified versus azimuth position. Using the indexing table, 
rotate the NFM reference surface to 0.0 Mil within + 1/3 MIL. At each of 8 
azimuth positions positions, 800 mils apart (45°)» activate the NFM by 
means of FIND NORTH. Simultaneously start a clock timer. When the ACTIVE 
light on the NFM is extinguished, record the time and the RDU reading. 
Subtract and record the difference between the table azimuth and the 
RDU reading. The accuracy of the system is the standard deviation of 
this difference from the mean value of the difference. The Time-to-Find 
North for each azimuth shall be less than 120 seconds. 

Polar Mode 

Time-True North (Below Arctic Circle) 

Insert a Northing of 737*4 Km and an Easting of 500 KM by means of the 
Front Panel. These values are directly below the Arctic Circle. Turn 
the NFM to OFF and then to ON. Verify that the time is less than 120 sec. 


45 H 


SEUURI TV NOTATION 


CODE IPENr NO 

SPEC NO 

RLV 

56232 

4223-188837 

B 


ITT 


SHEET 6 Of 









SECURITY NOTATION 


ENGINEERING 

SPECIFICATION 


-A»sper^y 

« GYROSCOPE 


i_ 

GREAT NECK. N. Y. 11020 


3. 6 . 3 .2 Polar Mode Accuracy and Time-to-Time North 

Insert a Northing value of 7375 KM by means of the NFM front panel. Turn 
the NFM to OFF (the NFM now is programmed for operation in latitudes in 
excess of +66.5°)• Repeat the procedure of 3*6.2. The Time-to-Find North 
for each azimuth shall be less than 240 seconds. 

3.6.4 Mis-Level Test 

This test requires that a test stand capable of very accurate vertical 
positions be used. If the indexing table used for azimuth accuracy tests 
is not capable of accurate vertical settings, an alternate test stand can 
be used. The RDU and external power are required at this stand. If this 
is the case, mount the NFM on this mis-level test stand. Perform NFM 
Northings and adjust azimuths until the RDTJ reads out between 6399.8 and 


0000.2 Mils. 

Perform a Northing at level, tilted 0.25° up, 0.5° up, level 0.25° down, and 
0 . 5 ° down. Record the data in measured data column. If the reading is 
63 XX, subtract 6400 and record difference in calculated data column. For 
readings of 00XX enter same number in both measured and calculated data 
columns. Calculate the mean value of the six data items for North in 
calculated data column. Rotate the NFM to the 1600 MIL +0 . 2 mil azimuth 
position (EAST). Repeat the above Northing sequence for level, 0.25° left 
tilt, 0.5° left, level, 0.25° right tilt and 0-5° right. Record the data. 

For East data subtract 1600 from measured data and record difference in 
calculated column. Calculate the mean value of the next six data items 
for East in calculated data column. Compute a standard deviation of 
the twelve readings from their respective mean value. The standard deviatiorj 
shall be equal to or less than 1.0 Mil. 

3*7 Shipment 

The NFM shall be set to 500*® Easting and 4000 KM Northing at the con¬ 
clusion of this test. Perform and verify. 

Verify that the NFM can be packaged within container Part No. MS 27684-17 
with lid Part No. MS 27684-23. 


St wURI ty notation 


• OHM I4A 


59 


CODE IDENT. NO 

56232 

SPEC NO. 

4223-188837 

RLV 

B 


shKT - 7. nC__l4, 










{ SWITCH 


m 


A B C D E F H 


NFM TEST CONNECTOR 

(VIKING INDUSTRIES VR 7/4AG19) 


NORTH 


' SWITCH 


' POWER 


}_J i 


' SUPPLY ! 


+ 24VDC 


FIGURE 1 


SECURITY NOTATION 


CODI'ltiYNT.NO. sitcno. 

56232 4223-183837 


! •" LI 


3 of lU 




















* 


ENGINEERING 



SECURITY NOTATION 

SPECIFICATION 

•1 C>A05wCi^c 

GREAT NECK. N. Y. 11020 



REV I 
SY- 


1 

14.0 NFM ACCEPTANCE TEST DATA SHEET 



10 H 


15 H 


20 —i 




30-H 


35—1 


40—( 


45 —^ 


T.S. Paragraph Record Data Spec 


3 .2.1 

Size Conformity 


3 .2.2 

Weight 

4.0^ 

3-3 

Controls and Display 

N/A 

3.4 

Test Set Up 

N/A 

3-5.1 

Ease of Monitoring 

N/A 

3.5.2 

Cycle Time 

.120 SEC 

RDU Operates 

N/A 


RDU Data 



NFM DATA 



Difference 

— 0.5 MIL 

3.5.3 

Display Increases 

N/A 

Display Decreases 

N/A 


Grid North 



True North 




. 11 MILS 


Inserted Grid Conv. 

11 MILS 


Send Data 

N/A 

3.5.4 

(verify re-display) 
Calculated Grid Conv. 

21 MILS 

3.5.5 

Alarm Light 

N/A 


S-V.OHITY NOTATION 


coo: IDE NT. NO. 

SPEC NO. 

r.i 

56232 

4223 -1 B3337 

p 


r :r - T °-gf il. . 



V 


EO.lM 144 l I 210b 


01 












ENGINEERING 

SPECIFICATION 


GREAT NECK. N. Y. 11020 


SECURITY NOTATION 


=0 ,'■= P 2 


>YM_| 

3-6.2 Turn Table Accuracy and Time-To-Time North 


5-4 


io H 


15-4 


20 -4 


■ 5-1 


30H 


3a— 


Index Table RDU Time Error 

0 MILS - _ 


800 MILS 


1000 MILS 


2400 MILS - - 


3200 MILS 


4000 MILS 


4800 MILS 


5000 MILS 


—120 SEC 


• ±120 ■ SEC 


1420. SEC 



-120 SEC 


^120 SEC 


-120-. SEC 


1320. SEC 


Mean 


45-4 


Std. Dev. 


c 1 MIL 


'JRITY NOTATION 


• 

COOL 101 NT. NO. 

[“spec no. 

r 

1 

56232 

4223-188837 

1 


—--- 

I 3: ’LET 11 0 T 

L- - 






O A 


t 


ENGINEERING 

- r-SFSR^Y 


SECURITY NOTATION 

SPECIFICATION 

•* U'WCSCCVC 

GREAT NECK, N. Y. 11020 



10 —I 


15 —7 


20 H 


30-H 


3.6.3.1 Time-to—FIND North (Below Arctic Circle) 

Time 

3 . 6 . 3 .2 Polar Mode Turn Table Accuracy and Time-to-Find North 

Index Table RDD Time Error 

0 MILS - _ 


800 MILS 


1600 MILS 


2400 MILS 


3200 MILS 


4000 MILS 


4800 MILS 


5600 MILS 


< 120 Sec 


Spec 


• 2kC Sec 


240 Sec 


240 Sec 


-oLn Sec 


pirn Sec 


240 


Sec 


?4 o Sec 


?40 Sec 


Mean 


Std. Dev. _ ■S 1 MIL 










SECURITY NOTATION 


ENGINEERING 

SPECIFICATION 


«$=SPER3Y 


GYROSCOPE 


GREAT NECK. N. Y. 11020 


REV 
<• •«< 


S-^ 




20 H 


T.S. Paragraph 

3.6.4 Mis-Level Test 

TILT 


LEVEL 
0.25° UP 
0.5° UP 
LEVEL 
0.25° DOWN 
0.5° DOWN 


LEVEL 

0.25° LEFT 
0.5° LEFT 
LEVEL 

0.25° RIGHT 
0.5° P7GHT 


MEASURED 

DATA 


CALCULATED 

DATA 


NORTH 


EAST 


MEAN 


MEAN 

Std. Dev.(Spec £ 1 MIL) 


HI TY NOTATION 


CODE IDENT NO 

56232 


UHM 0131 14A 


65 


SPEC NO 

4223-188937 

SHEET 1 3 °P ”14 


REV 

B 


K»C «9-9999 








ENGINEERING 

SPECIFICATION 


■^■SPERRV 

« GYROSCOPE 


SECURITY NOTATION 


GREAT NECK. N. Y. 1102Q 



3.7 Shipment 


NORTHING 


EASTING 


CONTAINER VERIFY 


SECURITY NOTATION 


FOHV 0-131 I4A 


CODE IDENT NO. SPEC NO. 


56232 


4223-188937 


SHEET 14 of 1 4 


■ 










APPENDIX D 

ENVIRONMENTAL TEST SPECIFICATION FOR 
GIMBAL MOUNT 




t 


ENGINEERING 

SPECIFICATION 


°F V 


A 


1.0 


^■SPERSY 

» GvROSCOPt 


SCOPE 


k 

1 SECURITY NOTATION 


GREAT NECK, N. Y. 11020 


5 — 


This document specifies the environmental test of the North Seeking 
Gyrocompass (NSG) gimbal mount. These tests are in compliance with the 
Purchase Description, North Seeking Gyrocompass 6 June 1978. 


2.0 APPLICABLE DOCUMENTS 



3.0 

3-1 


20 




3-2 




35 H 


40- 


- Purchase Description 6 June 1978, North Seeking 
Gyrocompass (NSG) 

XAS4536 February 17, 1977> Development Specification for 
North Finding Module. 

North Seeking Gyrocompass Operating and Maintenance Manual. 
REQUIREMENTS 
GENERAL 

All tests are to be conducted at the Sperry Gyroscope Company 
Environmental Test Laboratory using standard calibrated test equipment and 
the Sperry North Finding Module SPN 6075723, Tested as per Sperry Factory 
Acceptance Test Procedure 4222-188837, amended for a 3 minute Northing Cycle. 
TESTS 

3.2.1 Performance tests, which are to be conducted before, during 

(as specified), and after each test shall consist of a measurement 
of gimbal position after release from each of its four limit 
positions. 

3.2.2 For each performance test a NFM and battery are to be in place. 

Roll and pitch angles are to be measured initially. Then the NFM 
is to be displaced to the left limit and released. Settled roll & 
pitch are to be measured; then, similarly measured after displacement 
to the right, forward and rear limits. The five readings of roll or 
pitch shall have an rms excursion from mean value no greater than 

10 arc minutes. 


45 H 


.URITY NOTATION 


FORM 633114A 11 2156 



CODE IDENT. NO. 

56232 

SPEC NO. 

REV 


1 

SHEET 


68 










ENGINEERING 

SPECIFICATION 


SECURITY NOTATION 


GREAT NECK, N. Y. 11020 


TEMPERATURE 


3-3.1 

3.3.2 


. JURITY NOTATION 


FORM 633114A 11 2166 


Test Equipment - Tenney Temperature - Altitude Chamber EV 711. 

High Temperature - The NSG gimbal mount shall be subject to 
the test of Method 501.1, Procedure II of MIL STD BlOC with 
the exceptions noted in paragraph 4.3.1 of the Purchase Description. 
3.3.2.1 Set up NSG gimbal mount in the test chamber on a 

mount sufficiently stable and level to conduct performance 
tests. 

3.3*2.2 Perform the pre-temperature performance test of 3 . 2 .1. 

3.3- 2.3 Raise the internal chamber temperature to 52°C. 

3-3*2.4 Maintain the internal chamber temperature for 6 hours 
at 52°C. 

3.3«2.5 Conduct performance test of 3*2.1. 

3.3*2 .6 Return the chamber to standard ambient conditions and 
maintain for one hour. 

3.3*2.7 Conduct performance test of 3.2.1. 

Low Temperature - The NSG gimbal mount shall be subject to the 
test of Method 502.1, Procedure I of MIL STD 810C with the 
exceptions noted in paragraph 4.3.2 of the Purchase Description. 

3>3*3>1 Using the same setup as in 3•3•2.1 adjust the temperature 
chamber to 0°C. 

3.3- 3*2 Maintain the internal chamber temperature for 12 hours 

at 0°C. 

3*3*3*3 Conduct performance test of 3.2.1. 

3.3*3*4 Return the chamber to standard ambient conditions and 
maintain for one hour. 

3*3*3.5 Conduct performance test of 3.2.1. 


CODE IDENT. NO. 

56232 

SPEC NO. 

REV 


SHEET 1 







ENGINEERING 

SPECIFICATION 


SECURITY NOTATION 


GREAT NECK, N. Y. 11020 


VIBRATION 

The NSG gimbal mount shall be subject to the test of Method 5 1U.2, 

Procedure VIII of MIL STD BlOC using curve W of Figure 514-2-6 and Time 

Schedule A for Track Vehicles of Table 514.2-VI. 

3.4.1 Test Equipment - MB Model 010 Vibrator. 

3.4.2 Mount NSG gimbal mount to allow for proper leveling capability. 

3.4.3 Mount the NFM to the gimbal mount and conduct performance test 
of 3.2.1. 

3.4.4 Replace the NFM with an equivalent dummy mas3 and secure the 
gimbal with the traveling eager. 

3.4.5 Perform vibration sequence curve W of figure 514.2-6, Method 514.2, 
MIL ST^ 8l0 for 15 minutes. 

3.4.6 P!*.ce jFM back into the gimbal mount. Conduct performance test 
of 3.2.1. 

3.4.7 Repeat 3*4.2 through 3*4.6 for each of the other two orthogonal axis 
of the gimbal mount. 


The NSG gimbal mount shall be subject to the test of Method 516.2, 

Procedure I, MIL STD 8 lOC Figure 516.2-1 using 40g for a duration of 

11 milliseconds saw tooth pulse. 

3.5.1 Test Equipment - AVCO Type SM020 Shaped Pulse Shock Machine. 

3.5.2 Mount the NSG gimbal with NFM to a test fixture and conduct a 
pre-shock performance test of 3 * 2 . 1 . 

3*5.3 Replace the NFM with an equivalent dummy mass and secure the gimbal 

mount to the Shock Machine. Lock it in place using the traveling eager 

1.5.4 Apply three shocks of 40g 11 milliseconds saw tooth pulse. 

3.5.5 Repeat 3 . 5.3 and 3-5-4 for each of the other five orthogonal 
positions of MSG gimbal mount attitude. 

3.5.6 Conduct a post shock performance test of 3*2.1 with the gimbal mount 
returned to the test fixture of 3 * 5 . 2 . 


JRITY NOTATION 


FORM 633114A 


CODE IOENT, NO. 

56232 

SPEC NO. 


f ISMEET | 









ENGINEERING 

SPECIFICATION 


GREAT NECK. N. Y. 11020 


SECURITY NOTATION 


GYROSCOPE 


REV 

YM 


5-J 


10 -H 


4.0 NSG GIMBAL MOUNT ENVIRONMENTAL TEST DATA 

T.S. Paragraph 3.3-2.2 
Condition Pre Temperature 


'“1 


20 I 


-5 I 


20 1 


35 H 


AO—| 




Initial 
Left Limit 
Right Limit 
Fwd Limit 
Rear Limit 
Mean 

Std. Dev. 


ROLL 


PITCH 


_1- 

JRITY NOTATION 


CODE 1DENT. NO. - 1 

56232 

SPEC NO. 

REV 




SHEET | 


FORM 633114A 11 2166 


71 








ENGINEERING 

SPECIFICATION 


4.0 NSG GIMBAL MOUNT ENVIRONMENTAL TEST DATA 


T.S. Paragraph 3*3*2.5 
Condition S2°C 


Initial 
Left Limit 
Right Limit 
Fwd 'Limit 
Rear Limit 
Mean 

Std. Dev. 


FOAM 633114A 11 2165 



CODE IDE NT. NO. 

56232 

SPEC NO. 

fifv 


SHEET 1 










ENGINEERING 

SPECIFICATION 


GYROSCOPE 


GREAT NECK, N. Y. 11020 


SECURITY NOTATION 


PC V 

1 






4.0 

NSG GIMBAL MOUNT 

ENVIRONMENTAL TEST DATA 




T.S. Paragraph 

3-3-2.7 




Condition 

Post High Temp. 


5-1 


Initial 

ROLL 

PITCH 

10 — 


Left Limit 





Right Limit 





Fud Limit 





Rear Limit 




; Mean 

j Std. Dev. 


* -H 


30 H 


35-4 


«oH 




owCURirf NOTATION: 


PORM633114A 11 JIM 


_ 1 

CODE 10ENT. NO. 

56232 

j 

SPEC NO. “j 

REV 


1 

SHEET 


73 










ENGINEERING 

SPECIFICATION 


GYROSCOPE 


GREAT NECK. N. Y. 11020 


SECURITY NOTATION 


°EV 

VI 


4.0 


5 -^ 



NSG GIMBAL MOUNT ENVIRONMENTAL TEST DATA 

T.S. Paragraph 3.3.3.3 
Condition 0°C 


io —l 


15 H 


20 H 


Initial 
Left Limit 
Right Limit 
Fwd Limit 
Rear Limit 
Mean 

Std. Dev. 


ROLL 


PITCH 


H 


x>—\ 




35-H 





W.CURITY NOTATION: 


CODE IOENT. NO. 

56232 

SPEC NO. 

REV 


SHEET | 


FORM 53311*A 11 2156 


74 





















ENGINEERING 

SPECIFICATION 


GYROSCOPE 


GREAT NECK, N. Y. 11020 


SECURITY NOTATION 


°EV 

M 


5-4 


10 —\ 


15 — 


20 


25 H 


30 l 


35- 


40H 


46—| 


4.0 


NSG GIMBAL MOUNT ENVIRONMENTAL TEST DATA 


T.S. Paragraph 
Condition 


Initial 
Left Limit 
Right Limit 
Fwd Limit 
Rear Limit 
Mean 

Std. Dev. 


3-4.3 

Pre Vibration 

ROLL 


PITCH 


;URITY NOTATION 

CODE IDENT. NO. 

SPEC NO. 

REV 


56232 

h- 

1 



FORM 633114A 11 2166 


76 


SHEET 











ENGINEERING 

SPECIFICATION 


GYROSCOPE 


GREAT NECK, N. Y. 1)020 


SECURITY NOTATION 


REV 

M 


5-J 


4.0 


NSG GIMBAL MOUNT ENVIRONMENTAL TEST DATA 


T.S. Paragraph 
Condition 


3.4.6 

Post Vertical Vibration 


ROLL 


PITCH 


*-! 


20 —I 


-5 H 


30 I 


Initial 
Left Limit 
Right Limit 
Fwd Limit 
Rear Limit 
Mean 

Std. Dev. 


35-4 






_URITY NOTATION: 


FORM 633114A 11 2155 



CODE IDENT. NO. 

56232 

SPEC NO. 

REV 



SHEET j 


77 










FORMS33114A 11 2156 78 


T 







r 


engineering 

SPECIFICATION 


SECURITY NOTATION 


GREAT NECK, N. Y. 11020 


NSG GIMBAL MOUNT ENVIRONMENTAL TEST DATA 

T.S. Paragraph 3-4.7 

Condition Post Fore-Aft Vibration 


Initial 
Left Limit 
Right Limit 
Fwd Limit 
Rear Limit 
Mean 

Std. Dev. 


PITCH 


SECURITY NOTATION 


FORM 633114A 11 2156 


UUUC I . TV VS. 

56232 


SPEC NO, 

REV 

SHEET 1 










ENGINEERING 

SPECIFICATION 


GYROSCOPE 


GREAT NECK, N. Y. 11020 


SECURITY NOTATION 


REV 

M 


4.0 


NSG GIMBAL MOUNT ENVIRONMENTAL TEST DATA 

T.S. Paragraph 3*5.2 

Condition Pre Shock 


10 -i 


15 —I 

20 — 

i 
! 

t 25 — 

I 

30—I 


Initial 
Left Limit 
Right Limit 
Fwd Limit 
Rear Limit 
Mean 

Std. Dev. 


ROLL 


PITCH 


35 H 


45—1 


uRi TY NOTATION 



CODE IDENT. NO. 

56232 

SPEC NO. 

REV 



SHEET 


!' ' 4A 11 2155 


80 






ENGINEERING 

SPECIFICATION 


►SPERRY 


GYROSCOPE 

GREAT NECK, N. Y. 11020 


SECURITY NOTATION 


4.0 NSG GIMBAL MOUNT ENVIRONMENTAL TEST DATA 

T.S. Paragraph 3*5-2 

Condition Post Vertical Shock 


Initial 
Left Limit 
Right Limit 
Fwd Limit 
Rear Limit 
Mean 

Std. Dev. 



CODE I DENT. NO. | SPEC NO. 


FORM 633114A It 2156 


56232 

















FORM633114A 11 2166 


82 







ENGINEERING 

SPECIFICATION 


SECURITY NOTATION 


GREAT NECK. N. Y. U020 


NSG GIMBAL MOUNT ENVIRONMENTAL TEST DATA 

T.S. Paragraph 3-5*2 

Condition Post Fore-Aft Shock 


Initial 
Left Limit 
Right Limit 
Fwd Limit 
Rear Limit 
Mean 

Std. Dev. 


I SECURITY NOTATION: 


FORM 633114A II 2IS» 


PITCH 


83/84 


CODE IDENT. NO. 

56232 

SPEC NO. 

REV 


SHEET {