SG Brown Meridian User guide

A Division of VT TSS (UK) Limited
The information in this Manual is subject to
change without notice and does not represent
a commitment on the part of SG Brown
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VT TSS (SG Brown Division) Ltd
1 Garnett Close
Greycaine Industrial Estate
Watford
Hertfordshire WD24 7JZ UK
Telephone [phone]
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Meridian Gyrocompass
System Manual
Document P/N 060070
Issue 3.7
© SG Brown March 2004

Contents
DPN 060070 Issue 3.7 © SGBrown Page 1 of 6
CAUTIONARY NOTICES
Your attention is drawn to the following cautionary notices that apply throughout this Manual.
WARNING
The Meridian Gyrocompass weighs 15.5kg. To avoid personal injury, take proper pre-
cautions if you lift or move the equipment.
CAUTION
The Meridian Gyrocompass includes precision components and bearings. To avoid
causing damage to any part of the System, handle all items with care.
Retain the original transit cases so that you can use them to transport the system when
necessary. You will void the warranty if you use improper packing during transporta-
tion.
CAUTION
Severe damage to the Meridian Gyrocompass can occur if you move the gyrocompass
while the rotor is still spinning without the servo system in operation.
Note that the gyro rotor continues to spin for approximately five minutes after you
power-off the system.
To avoid potential damage to the Meridian Gyrocompass, always allow a period of five
minutes after power-off for the gyro rotor to come to rest before you attempt to move
the gyrocompass.
CAUTION
During operation, the gyrocompass must remain level to within ±45°. If it experiences
tilt greater than 45° in any direction, it will ‘topple’. Safety routines in the gyro software
will then power-off the gyro rotor and show alarm conditions on the RCU. To restore
normal operation, establish a level operating attitude and then power-on the gyrocom-
pass normally.
Never apply a tilt of more than 45° with the gyro rotor spinning or during the gyrocom-
pass initialisation procedure. Note that the gyro rotor continues to spin for approxi-
mately five minutes after you power-off the System.
CAUTION
If you install the gyrocompass in an enclosed space, make certain there is sufficient
ventilation and circulation of free air to allow effective cooling.
CAUTION
Do not make any connections to the gyrocompass with power on the supply cable.

Meridian Gyrocompass
Page 2 of 6 ©SGBrown Issue 3.7 DPN 060070
CAUTION
You will void the warranty if you make any modifications to this equipment without
prior permission from SG Brown.
DO NOT modify this equipment in any way without obtaining permission from SG
Brown.
CAUTION
You will void the warranty if you operate the gyrocompass outside the environmental
conditions detailed in Chapter 4 and in BS EN 60945.

Contents
DPN 060070 Issue 3.7 © SGBrown Page 3 of 6
CONTENTS
1 INTRODUCTION 1–1
1.1 System Description 1–3
1.1.1 Gyrocompass 1–3
1.1.2 Remote Control Unit 1–4
1.1.3 Auxiliary Inputs 1–4
1.1.4 Heading Outputs 1–5
1.2 Principle of Operation 1–5
2 INSTALLATION 2–1
2.1 Unpacking and Inspection 2–2
2.2 Physical and Electrical Installation 2–3
2.2.1 Selecting a location 2–3
2.2.2 Gyrocompass installation 2–4
2.2.3 External Remote Control Unit 2–9
2.2.4 Set the Gyrocompass DIP Switches 2–10
2.3 Alignment 2–12
2.4 Final Gyrocompass Installation Tests 2–12
2.5 Installation Drawings 2–13
3 OPERATING INSTRUCTIONS 3–1
3.1 Control Features 3–2
3.2 Initial Power-on 3–3
3.3 Operating Procedure 3–4
3.3.1 Latitude correction 3–4
3.3.2 Speed correction 3–4
3.3.3 DG operating mode 3–5
3.4 Error Modes 3–5
3.4.1 Loss of GPS 3–5
3.4.2 Loss of speed log 3–6
3.4.3 Gyrocompass system warnings and failures 3–6
3.5 Operating Considerations 3–8
3.5.1 General Operating Considerations 3–8
3.5.2 Corrections for Speed and Latitude 3–8
3.5.3 Operating at Extremes of Latitudes 3–8
3.5.4 Operating Considerations for High Speed Craft 3–9
4 TECHNICAL DATA 4–1
4.1 Specifications 4–1
4.1.1 Power Requirements 4–1
4.1.2 Performance (definitions as in ISO 8728) 4–1
4.1.3 Compensation 4–1
4.1.4 Environment 4–1
4.1.5 Signal Inputs 4–2
4.1.6 Signal outputs 4–2
4.1.7 Dimensions and Weight 4–2
4.1.8 Listener load requirement 4–3
4.1.9 Talker drive capability 4–3

Meridian Gyrocompass
Page 4 of 6 ©SGBrown Issue 3.7 DPN 060070
4.1.10 Standards 4–3
4.2 Data Formats 4–4
4.2.1 IEC 61162 Serial Data Formats – General information 4–5
4.2.2 Inputs 4–6
4.2.2.1 IEC 61162 input signals 4–6
4.2.2.2 Pulsed input 4–10
4.2.3 Outputs 4–11
4.2.3.1 IEC 61162 output signals 4–11
4.2.4 IEC 61162 sentence with Checksum 4–15
4.2.5 Other Output Formats 4–15
4.2.5.1 Course Recorder Output 4–15
4.2.5.2 Synchro Output 4–16
4.2.5.3 Resolver Output 4–16
4.2.5.4 Stepper S-Code 4–16
4.2.5.5 Rate of Turn 4–16
5 MAINTENANCE 5–1
5.1 Built-in Test Equipment 5–2
5.1.1 Azimuth Drift Adjustment 5–3
5.1.2 Azimuth Bias Adjustment 5–3
5.2 Test Connector 5–4
5.3 Diagnostic Output Sentence 5–6
A OPERATING THEORY A–1
A.1 North-seeking Gyroscope A–2
A.2 Gyrocompass Corrections A–5
A.2.1 Latitude Correction A–5
A.2.2 Gyro Damping A–5
A.2.3 Speed Error A–6
A.3 Summary A–7
B CERTIFICATION A–1

Contents
DPN 060070 Issue 3.7 © SGBrown Page 5 of 6
TABLE OF AMENDMENTS
Old Issue New Issue Date Details
-2.0 11 May 2000 New release.
2.0 2.0A 12 Dec 2000 Corrected identification of Azimuth Bias potentiometer and
other details. Include DIP switch default settings.
2.0A 2.0B 1 Mar 2001 Modify power connection details.
2.0B 2.0C 23 Apr 2001 Add notification to avoid product modifications.
2.0C 3.0 Aug 2002 Substantial amendments to reflect product enhancements
3.0 3.1 Sept 2002 completion of enhancement features including compliance with
IEC 61162
3.1 3.2 Jan 2003 Minor amendments and description of Diagnostic Output Sen-
tence.
3.2 3.3 Feb 2003 Modification to specifications and addition of Appendix B to
demonstrate Certificate of Type Approval.
3.3 3.4 Mar 2003 Minor amendments to a display warning and a note referring to
confirming software release.
3.4 3.5 July 2003 Note added regarding modification kit available for alternative
orientations when attempting correct speed compensation.
3.5 3.6 August 2003 Minor amendments to specifications throughout
3.6 3.7 March 2004 Amendments to alarm warning / failure designation

Meridian Gyrocompass
Page 6 of 6 ©SGBrown Issue 3.7 DPN 060070

1 – Introduction
DPN 060070 Issue 3.7 © SG Brown Chapter 1 Page 1 of 6
1 INTRODUCTION
The Meridian Gyrocompass is a master heading reference instrument that applies the charac-
teristics of a dynamically tuned gyroscope and the effects of gravity and earth rotation to pro-
vide a true north reference.
The Meridian Gyrocompass specification makes the System ideal for installation and opera-
tion on board vessels of almost any size and in a wide range of applications.
Among the standard features of the Meridian Gyrocompass are:
❐A short settling time
❐Operation from a 24V DC electrical supply
This Manual is an important part of the Meridian Gyrocompass. It describes the System and
contains full installation and operating instructions. You should retain the Manual with the
System for use by personnel who will install and operate it.
Installation and operation of the Meridian Gyrocompass are not complex tasks. However, you
should spend time to familiarise yourself with the contents of this Manual before you start to
install or use the System. Time spent in identifying the task sequence now will ensure your
System is operational in the minimum of time.
WARNINGS
Where appropriate, this Manual includes important safety information highlighted as
WARNING and CAUTION instructions. You must obey these instructions:
WARNING instructions alert you to a potential risk of death or injury to users of the
System.
CAUTION instructions alert you to the potential risk of damage to the System.
For your convenience, the Table of Contents section includes copies of all the
WARNING and CAUTION instructions included in this Manual.
Throughout this Manual all measurements conform to the SI standard of units unless other-
wise indicated.
For your convenience, this Manual includes several sections, each of which describes specific
features of the Meridian Gyrocompass:
You should read sections 1 and 2 before you attempt to install the System:
Section 1 contains introductory notes and describes those items supplied as standard.
Section 2 describes how to select a suitable location for the gyrocompass. This section
includes full instructions to install the System and connect it to external equipment.

Meridian Gyrocompass
Chapter 1 Page 2 of 6 © SG Brown Issue 3.7 DPN060070
You should read sections 3 and 4 before you use the System:
Section 3 describes how to operate the Meridian Gyrocompass.
Section 4 includes the System specifications and descriptions of the data formats.
You should read sections 5 if you suspect a fault on the System:
Section 5 describes how to use the internal 60-way test connector and explains how to con-
duct simple adjustments with the gyrocompass housing removed.
This Manual also contains the following appendices:
Appendix A explains how a gyroscope can be made north seeking for use in a gyrocompass.
CAUTION
You will void the warranty if you make any modifications to this equipment without
prior permission from SG Brown.
DO NOT modify this equipment in any way without obtaining permission from SG
Brown.