iXBlue GAPS User Manual

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GAPS

Carbon V.1

User Guide

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GAPS – User Guide

form or by any means, whether electronic, printed manual or otherwise, including

but not limited to photocopying, recording or information storage and retrieval

systems, for any purpose without prior written permission of iXBlue.

Disclaimer

iXBlue specifically disclaims all warranties, either express or implied, included but

not limited to implied warranties of merchantability and fitness for a particular

purpose with respect to this product and documentation. iXBlue reserves the right

to revise or make changes or improvements to this product or documentation at any

time without notifying any person of such revision or improvements.

In no event shall iXBlue be liable for any consequential or incidental damages,

including but not limited to the loss of business profits or any commercial damages,

arising from the use of this product.

Trademarks

Microsoft, MS-DOS and Windows are registered trademarks of Microsoft

Corporation. Intel and Pentium are registered trademarks and Celeron is a

trademark of Intel Corporation.

MU-GAPS-AN-003 Ed. L – May 2012

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GAPS – User Guide

Warranty

iXBlue provides a standard warranty of one (1) year covering this product against any

defect in materials or manufacture. The warranty starts from the date of shipment of the

product from iXBlue’s manufacturing premises to customer’s location and its duration is

indicated in the certificate of warranty delivered with the product. In the event that a defect

in materials or manufacture becomes obvious during the stipulated warranty period,

iXBlue will undertake, at its sole discretion, either to repair the defective product, bearing

the cost of all parts and labor, or to replace it with an identical product.

In order to avail itself of this warranty, Customer must notify iXBlue of the defect before

expiry of the warranty period and take all steps necessary to enable iXBlue to proceed.

Customer shall be responsible for the packaging and the shipment of the defective

product to the repair center notified by iXBlue, the cost of such shipment being borne by

Customer. iXBlue agrees to bear the cost of return freight, based on CPT (Cost Paid To)

Customer’s airport location, import tax-free.

This warranty shall not be construed as covering defects, malfunctions or damages

caused by improper use or inadequate maintenance of the product. Under no

circumstances shall iXBlue be due to provide repair or replacement under this warranty in

order a) to repair damage caused by work done by any person not representing iXBlue for

the installation, repair or maintenance of the product ; b) to repair damage caused by

improper use or connection to incompatible equipment, and specifically, the opening of

the housing of the equipment under warranty shall cause the warranty to be automatically

cancelled ; c) to maintain any product that has been modified or integrated into a larger

configuration, if such modification or integration increases the duration or difficulty of the

maintenance of said product.

This warranty covers the product hereunder and is provided by iXBlue in place of all and

any other warranty whether expressed or implied. iXBlue does not guarantee the

suitability of the product under warranty for sale or any specific use. iXBlue’s liability is

limited to the repair or replacement of defective products, this being the sole remedy open

to Customer in the event the warranty becomes applicable. iXBlue cannot be held liable

for indirect, special, subsequent or consequential damage, irrespective of whether iXBlue

has or has not received prior notification of the risk of occurrence of such damage.

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GAPS – User Guide

Export Regulation

This product is classified as a dual-use good: it has been developed for non-military use,

but could be used for military applications.

As a consequence, this product is subject to dual-use goods export control procedures:

• iXBlue can deliver this product freely to France or any other country of the European

Union;

• iXBlue can export this product under its own Community General Export Authorization

EU 001 to the following countries: Australia, Canada, USA, Japan, New-Zealand,

Norway and Switzerland;

• iXBlue can also export this product to other countries but only through the issuance of

an individual export license by the French authorities.

Once in its country of first destination:

• From a country member of European Union, this product is free of movement (travel)

as long as it remains within the European Union;

• From a country member of European Union, this product can only be re-exported to a

non European Union member country under the dual-use goods export control

procedures set forth by the national authorities;

• From another country, this product can only be re-exported under both the conditions

of the original export license from France (depending on its type and content) and the

dual-use goods export control procedures set forth by the national authorities.

If an individual export license has to be issued by the French authorities, iXBlue requires

you to provide as needed a description of your usual activity (and the one of the end-user

if different) and the end-user to fill out an end-user certificate which includes:

• The description of the intended application of the product

• A commitment not to re-export the product (without applying for an export license to

the competent national authorities as set above).

This product cannot be exported or re-exported to Cuba, Syria, North Korea, Libya, Sudan

and Iran.

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GAPS – User Guide

Overview of GAPS User Guide

This document is the User Guide for iXBlue’s GAPS. It must be read and understood prior

to using the GAPS system. The manufacturer shall in no case be held liable for any

application or use that does not comply with the stipulations in this manual. This issue is

updated for use with GAPS MMI software 2.09.01 and higher.

The GAPS User Guide is divided into six parts:

• Part 1: Introduction and Technical Description

This section contains a general and technical description of GAPS as well as the technical

conventions that apply.

• Part 2: Installing GAPS

In this section you will find the procedure for installation the GAPS system, to assess its

geometrical configuration parameters, and to plan all connections to external systems.

• Part 3: Configuring GAPS

In this section you will find the procedure for GAPS configuration with the MMI Software. It

describes how to configure the GAPS unit and the transponders with all required

parameters before operating the system.

• Part 4: Operating GAPS

This section provides the full description of GAPS performance and operation.

• Part 5: Maintenance

This section provides the preventative and corrective maintenance for GAPS.

• Part 6: Library Interface

This section is the protocol library documentation for GAPS. It contains the description of

all available GAPS protocols.

The abbreviations and acronyms used in this manual are listed hereafter.

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Text Usage

Bold

Bold text is used for items you must select or click in the

software. It is also used for the field names used into the dialog

box.

Courier

Text in this font denotes text or characters that you should enter

from the keyboard, the proper names of disk Drives, paths,

directories, programs, functions, filenames and extensions.

Italic

Italic text is the result of an action in the procedures.

Icons

The Note icon indicates that the following information is of interest to the operator and

should be read.

HE CAUTION ICON INDICATES THAT THE FOLLOWING INFORMATION SHOULD BE READ TO FORBID

OR PREVENT PRODUCT DAMAGE

HE WARNING ICON INDICATES THAT POSSIBLE PERSONAL INJURY OR DEATH COULD RESULT

FROM FAILURE TO FOLLOW THE PROVIDED RECOMMENDATION

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Abbreviations and Acronyms

DGPS Differential Global Positioning System

FOG Fiber Optical Gyroscope

GAPS Global Acoustic Positioning System

GPS Global Positioning System

IIF Individual Interrogation Frequency

IMU Inertial Measurement Unit

INS Inertial Navigation System

MMI Man Machine Interface

MFSK Multi-Frequency Shift Keying

NA Not Applicable

GAPS – User Guide

NIS Noise Isotropic Spectrum

NMEA National Marine Electronics Association

RTK Real-Time Kinematics

SNR Signal to Noise Ratio

USBL Ultra Short Base Line

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Table of Contents

I INTRODUCTION AND TECHNICAL DESCRIPTION ...................................................................................1

I.1 System Overview .....................................................................................................................1

I.2 Acoustic Positioning Principles .............................................................................................3

I.3 Technical Description ..............................................................................................................4

I.3.1 Overview ...............................................................................................................................4

I.3.2 GAPS Unit .............................................................................................................................5

I.3.3 Acoustic Transponders .........................................................................................................6

I.3.3.1 Acoustic Transponder MT8x2 and ET8x2 Series .................................................................7

I.3.3.2 Acoustic Transponder BT812 Series ..................................................................................10

I.3.4 Integrated DGPS.................................................................................................................10

I.4 Conventions and Specifications ..........................................................................................11

I.4.1 General Characteristics ......................................................................................................11

I.4.2 Geometrical Conventions ...................................................................................................11

I.4.3 Mechanical Specifications ..................................................................................................14

I.4.4 Electrical Specifications ......................................................................................................15

II INSTALLING GAPS.........................................................................................................................19

II.1 Checking of the Pack Contents ............................................................................................19

II.2 Installing the Acoustic Antenna ...........................................................................................20

II.2.1 Recommendations Prior to Installation ...............................................................................20

II.2.1.1 Noise Level .........................................................................................................................20

II.2.1.2 Reflective Surfaces .............................................................................................................20

II.2.1.3 Corrosion ............................................................................................................................20

II.2.2 Installation Principles ..........................................................................................................21

II.2.3 Deployment Examples ........................................................................................................25

II.3 Installing the Easy Connect Box ..........................................................................................28

II.3.1 Connections on the Front Face ..........................................................................................29

II.3.2 Connections on the Back Face ...........................................................................................29

II.4 Checking the Electrical Ground Continuity ........................................................................31

II.5 Installing the GPS Antenna ...................................................................................................32

II.5.1 Installing an External GPS ..................................................................................................32

II.5.2 Installing the iXBlue DGPS .................................................................................................32

II.5.3 Measuring the GPS Lever Arms .........................................................................................33

II.5.4 Setting the GPS Time .........................................................................................................36

II.6 Installing a Transponder .......................................................................................................36

III CONFIGURING GAPS .....................................................................................................................37

III.1 Installing the Man Machine Interface ...................................................................................37

III.2 Overview of the Man Machine Interface ..............................................................................38

III.2.1 Starting the Man Machine Interface ....................................................................................38

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III.2.2 Main Window ..................................................................................................................... 40

III.2.3 Color Code ......................................................................................................................... 41

III.3 Configuring GAPS ................................................................................................................. 42

III.3.1 Configuring the Survey Parameters ................................................................................... 42

III.3.2 Configuring the System Parameters .................................................................................. 46

III.3.3 Configuring the Serial Link ................................................................................................. 48

III.3.4 Configuring the Interface Parameters ................................................................................ 49

III.3.5 Configuring the GPS Parameters ...................................................................................... 50

III.3.6 Configuring the Processor Parameters .............................................................................. 51

III.3.7 Configuring the Acoustic Array Parameters....................................................................... 53

III.3.8 Configuring the Output Parameters ................................................................................... 54

III.3.9 Defining a Sound Velocity Profile ...................................................................................... 56

III.3.10 Configuring the Transponder Parameters ......................................................................... 58

III.4 Monitoring the GAPS in Operation ...................................................................................... 64

III.4.1 Controlling The Real Time Data ........................................................................................ 64

III.4.2 Visualizing with the Absolute View .................................................................................... 65

III.4.3 Visualizing with the Relative View ..................................................................................... 67

III.4.4 Visualizing with the Depth View ......................................................................................... 68

III.4.5 Controlling the GAPS Status ............................................................................................. 69

III.5 Recording the Data ............................................................................................................... 72

IV OPERATING GAPS ....................................................................................................................... 73

IV.1 Performances ........................................................................................................................ 73

IV.1.1 Position accuracy for MT8, MT9 and ET8 Transponders .................................................. 73

IV.1.2 Multi Path ........................................................................................................................... 74

IV.1.3 Range versus Noise Level ................................................................................................. 75

IV.1.4 Accuracy versus SNR ........................................................................................................ 76

IV.2 Initializing and Configuring a Survey.................................................................................. 77

IV.2.1 Operating Modes ............................................................................................................... 77

IV.2.1.1 Synchronization Mode / Recurrence .................................................................................. 77

IV.2.1.2 Two Modes ........................................................................................................................ 78

IV.2.1.3 Multi Transponders Mode .................................................................................................. 78

IV.2.2 Initializing GAPS ................................................................................................................ 79

IV.2.3 Configuring the Mission Parameters .................................................................................. 82

IV.2.4 Installing the transponders ................................................................................................. 83

IV.3 Monitoring the Survey .......................................................................................................... 84

IV.3.1 Visualizing the Trajectory ................................................................................................... 84

IV.3.2 List of the System Status ................................................................................................... 84

IV.3.3 List of the Warning Messages and Troubleshooting ......................................................... 85

IV.3.4 Error Messages .................................................................................................................. 86

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V MAINTENANCE ...............................................................................................................................89

V.1 Preventive Maintenance ........................................................................................................89

V.1.1 Precautions .........................................................................................................................89

V.1.2 Cleaning Hydrophones .......................................................................................................91

V.1.3 Testing GAPS before Deployment......................................................................................92

V.1.3.1 Required Equipment ...........................................................................................................92

V.1.3.2 Testing Communication ......................................................................................................93

V.1.3.3 Testing Transmission ..........................................................................................................94

V.1.3.4 Testing Reception ...............................................................................................................95

V.1.3.5 Testing Monitoring of Heading/Roll/Pitch ...........................................................................96

V.1.3.6 Testing GPS Input ..............................................................................................................97

V.1.3.7 Testing GAPS Standard Output ..........................................................................................98

V.2 Corrective Maintenance ........................................................................................................99

V.3 System Upgrade .................................................................................................................. 103

V.3.1 Purpose ............................................................................................................................ 103

V.3.2 Recommendation ............................................................................................................. 103

V.3.3 Upgrading the INS Firmware ........................................................................................... 103

V.3.4 Upgrading the CPU and/or 4Ways Firmware .................................................................. 106

VI LIBRARY INTERFACE ................................................................................................................... 109

VI.1 Input Protocols .................................................................................................................... 109

VI.1.1 xxGGA ............................................................................................................................. 109

VI.1.2 xxZDA .............................................................................................................................. 110

VI.1.3 PMEVL ............................................................................................................................. 110

VI.2 Output Protocols ................................................................................................................. 111

VI.2.1 GAPS STANDARD .......................................................................................................... 111

VI.2.2 HIPAP HPR 418 BCD (rev C) Mobile or Fixed ................................................................ 115

VI.2.3 HIPAP HPR 400............................................................................................................... 118

VI.2.4 NAUTRONIX ATS II ......................................................................................................... 119

VI.2.5 POSIDONIA 6000 ............................................................................................................ 120

VI.2.6 IXSEA USBL INS 1 .......................................................................................................... 121

VI.2.7 IXSEA USBL INS 2 .......................................................................................................... 122

VI.2.8 PHINS STANDARD MESSAGE ...................................................................................... 125

VI.2.9 HEHDT ............................................................................................................................. 127

VI.2.10 HALLIBURTON ................................................................................................................ 127

VI.2.11 NAVIGATION ................................................................................................................... 129

VI.2.12 SIMRAD EM ..................................................................................................................... 130

VI.2.13 SOC AUTOSUB ............................................................................................................... 131

VI.2.14 GPGGA Ship .................................................................................................................... 132

VI.2.15 GYROCOMPASS ............................................................................................................ 132

GENERAL INDEX ................................................................................................................................ 135

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I INTRODUCTION AND TECHNICAL DESCRIPTION

I.1 System Overview

The Global Acoustic Positioning System, GAPS, is a portable Ultra Short Base Line

(USBL) with integrated Inertial Navigation System (INS) and Global Positioning System

(GPS).

GAPS – User Guide

Plug and Play

Accuracy

GAPS

Operation

Principles

The GAPS system is recommended for mobile or fixed installations. It can be combined

with an additional hoisting system. It is a plug & play installation and calibration is

required neither before using it nor after reinstalling it.

The GAPS system is used to deliver:

• The position of one or more underwater objects or vehicles, which can maneuver at

depth up to 3,000 meters. Greater depths are possible depending on the beacon type

used.

• The accuracy is up to 0.2% accuracy of the Distance to Go (or DTG at 1σ) depending

on environmental and operational conditions.

• The heading, attitude, motion and position of the support vessel or buoy.

The underwater objects or vehicles are located using acoustic transponders, GAPS

acoustic array is deployed underwater and is typically mounted below the ship hull or on a

buoy (see Figure 1).

Figure 1 -

The operation principle is based on a bi-directional exchange of underwater acoustic

signals between the acoustic transponders and the GAPS unit that comprises one

transducer for transmitting and four reception hydrophones.

The GAPS has an operating field over 200 degrees coverage below the ship (see Figure

ring the positioning operations it can be used at 3 or 4 knots or more depending on

2). Du

the expected performances and at 12 knots during the transit operations.

GAPS typical mounting

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GAPS – User Guide

Figure 2 - GAPS Operating Field

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I.2 Acoustic Positioning Principles

The positioning of the acoustic transponder(s) is performed as follows (see Figure 3):

• The transmitting transducer sends an interrogation signal to the transponder.

• The four receiver hydrophones of the GAPS unit receive the MFSK reply from the

transponder.

• The GAPS processing unit

 detects the signal,

 measures the phases of the signals arriving at the four hydrophones and the

elapsed time between the interrogation and the reply.

• GAPS takes into account the attitude of the acoustic array (provided by the internal

fiber-optic gyros at the exact moment of the reception of the signal). The processing

unit deduces the relative position of the transponder.

• The INS sensor also processes also the data coming from the DGPS antenna with its

own gyros and acceleration sensors in order to accurately determine the absolute

GAPS – User Guide

position of the acoustic array at the exact moment when the transponder signal has

been received.

• The absolute position of GAPS is given by the GPS. The position of the transponder

relative to GAPS position is computed. GAPS can then provide the accurate absolute

position of the transponder.

• This absolute position feeds a Kalman filter, which is able to provide an estimation of

the current position of the transponder in real-time.

• Additionally, the position, heading, roll and pitch of the acoustic array (or the ship) are

available as output.

Figure 3 - GAPS Operation Synoptic

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I.3 Technical Description

I.3.1 OVERVIEW

The GAPS system consists of four main parts (see Figure 4)

• The acoustic array, i.e. the GAPS unit (see section I.3.2)

GAPS – User Guide

ECB

Control

• One

• The DGPS integrated a

• Man Machin

Other ele

A junction box named Easy Connect Box (ECB) simplifying the connections between the

GAPS unit and other devices is also available (see section II.3 of this manual).

GAPS does not need any external sensor to provide the position of the transponders but

depe

used in order to

• Increase the accuracy in noisy environments

• Simplify the installation of GAPS

The Control System is any PC on which the MMI Software is installed, it can be

• Either directly connected to GAPS through the MMI DIALOG RS 422 serial link

• Or to the MMI DIALOG RS232 serial link available on the junction box

The purpose of the Control System is

or several acoustic transponders that can be mounted on objects, vehicles,

divers etc. (see section I.3.3)

ntenna (see section I.3.4)

e Interface (MMI) software used to configure (mandatory) and to

monitor (optional) the real time data (see section III of this manual)

ments of the system are listed below:

nding on the conditions, external sensors – in particular a pressure sensor - can be

• To configure GAPS (input/output configuration, sound velocity profile, etc) if necessary

• To visualize the position(s) of the transponder(s)

The use of the Control System is not mandatory once GAPS is configured: GAPS stores

all its settings when turned off and resumes its last behavior when started up.

Cables

Three cables are used in the GAPS system:

• The 50 m main cable between GAPS and the ECB. An optional length of 100 m is also

available upon request. This cable is fitted with a 16-pin SUBCONN at one end (GAPS

side) and a 19-pin SOURIAU at the other end (ECB side).

• The Y cable can be used to connect the GPS directly to the GAPS. A 6 pins

SUBCONN end is connected to the GPS. The two other ends link the GAPS to the

ECB using the 50 m main cable.

• The 10 m GPS cable links the Y cable to the GPS antenna. It is equipped with 6-pin

SUBCONN connectors.

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GAPS – User Guide

GPS

If the expected accuracy of an external GPS is greater than the GAPS integrated DGPS, it

is possible to connect it to the ECB (through the External GPS RS 232 serial link) and to

use its positioning data. In that case, the “Y” cable is not used.

I.3.2 GAPS U

NIT

Figure 4 – GAPS System Components

Figure 5 - GAPS Unit

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GAPS – User Guide

Mechanical Description

Contents

Power Supply

GAPS Unit

GAPS has a carbon housing to deal with weight and mechanical characteristics. It is

composed of (see Figure 5)

An upper disk for handling

•

• A transmission transducer

• Four reception hydrophones of different lengths to take 3D measurements

• The four hydrophones are protected by plastic caps protect them

• A 16-pin SUBCONN connection plug

The GAPS unit contains:

• The acoustic electronics for reception based on the MSFK Chirp modulation technique

• An Inertial Navigation System (INS)

• The acoustic transmitter electronics

GAPS must be powered by a 28 to 36 V - 50W - DC power supply.

The GAPS unit ensures

• the transmission of The acoustic (or electrical) triggering signals to the Transponders,

• The reception of the replies,

• The processing taking into account the attitude provided by the fiber-optic sensor

• The transmission of the results.

I.3.3 ACOUSTIC TRANSPONDERS

Five different acoustic transponders are compatible with the GAPS system:

• MT8: the standard GAPS transponder, see a description in section I.3.3.1 and in the

specific User Guide

• ET8: equivale

dimensions, please refer to the ET8 User Guide

• BT8: directive transponder, configured only in factory (IIF, code), robust design,

batteries inside, single recurrence value at 6.7 s, no responder mode, please refer to

the BT8 User Guide

• MT9: the new generation transponder, compatible with MT8 and is configured using

control software, use additional codes and batteries, please refer to the MT9 User

Guide

• ORE 435xB: monochromatic acoustic transponder, please refer to the manufacturer

User Guide

nt to the MT8 transponder with 10 times longer autonomy with larger

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I.3.3.1 Acoustic Transponder MT8x2 and ET8x2 Series

The Acoustic Transponder series designed to be used with GAPS are:

• iXBlue MT 832 E – HD – R: Designed to depths up to 3,000 m (remote transducer)

• iXBlue MT 832 E – R: Designed to depths up to 3,000 m

• iXBlue MT 862 S – HD – R: Designed to depths up to 6,000 m (remote transducer)

• iXBlue MT 862 S – R: Designed to depths up to 6,000 m

• iXBlue ET 862 S – HD – R: Designed to depths up to 6,000 m (remote transducer)

• iXBlue ET 862 S – R: Designed to depths up to 6,000 m

GAPS – User Guide

Specifications

Acoustic Level

188 ± 4 dB ref. 1µPa at 1m (other levels 191 dB or 185 dB available).

Reception Channel (IIF)

The reception channel frequency, or IIF (Individual Interrogation Frequency) is selectable

with a switch (19.5, 20.0, 20.5 or 21 kHz) located on the lower end plate of the

transponder. This switch is also used to turn off the transponder or to check the batteries

(Test position). Only one reception channel is available on this series of transponder.

Transmission Channel

When the transponder is triggered by an IIF signal (or electrically triggered), it replies with

a MFSK chirp signal. This signal is composed of fourteen various pulses at frequencies

ranging from 22 to 30 kHz.

Chirp Code

The order of transmission of these frequencies is determined by the code of the chirp (22

or 23). The default code is 22.

Turn Around Time

There is a delay between the reception of the triggering signal and the transmission of the

reply. See Figure 6.

In resp

onder mode, this delay is fixed at 2 ms, when the switch position is 0 or 1 otherwise

the settings are the same as in transponder mode.

In transponder mode, this delay is adjustable from 20 to 90 ms. When the switch, located

inside the transponder (see the MT832 User Guide for further information) is in position

• 0 and 1, the delay is 20 ms

• N = 2 to 9, the delay is N x 10 ms

The default turn around time is 90 ms. See Figure 6.

Blanking Ti

After having transmitted, no other transmission is possible for a certain time. See Figure 6.

This pe

riod is called the blanking time and is adjustable from 0.5 to 9.9 s. The default

blanking time is 0.8 s.

The Chirp Code, Turn Around Time and Blanking Time can be selected using the switches

located inside the transponder (see the MT832 User Guide for further information).

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Figure 6 - Sketch of a 2 s Acoustic Transponder Recurrence

GAPS – User Guide

Optional

Features

Responder Mode

Every iXBlue acoustic transponder with the letter "-R" at the end of its designation (e.g.

MT 832 E-R) is equipped with a waterproof plug, that is used for:

• The Electrical Triggering of the transponder in Responder mode

• The External Power Supply of the transponder

Electrical Triggering

The transponder can be triggered by a 5 V differential active high signal (rising edge

trigger) 10 ms pulse sent to this input (minimum value).

On the MT 832 series, there is no need to set the transponder either to transponder or

responder mode: if an electrical triggering signal is received through the responder input,

the transponder automatically switches to responder mode and the acoustic IIF channel is

inhibited.

After 20 seconds without receiving any electrical trigger, the transponder switches back to

the Transponder mode and starts to listen to its reception channel.

Power Supply

The transponder is usually externally powered. The batteries will be used only (and

automatically) if the external supply is lost. With full batteries and transmission at 188 dB

(factory settings), approximately 50,000 chirps can be sent by the transponder. The power

can be raised to 191 dB to improve the range but in this case the maximum chirp number

decreases. The power voltage can be any value from 15 to 40 V.

Table 1 - Power Supply Specifications for MT8x2 Series

External power Range 15 - 40 VDC, 20 W peak

Consumption 900 µA under 9 VDC and 550 µA under 25 VDC

Internal back-up batteries 3 packs of 3 Lithium batteries

Type DL123A (size 2/3 A, ≅ 3.9 Ah) from DURACELL

Type CR123A from VARTA

MU-GAPS-AN-003 Ed. L – May 2012

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GAPS – User Guide

Table 2 - Power Supply Specifications for ET8x2 Series

External power Range 15 - 40 VDC, 20 W peak

Consumption 900 µA under 9 VDC and 550 µA under 25 VDC

Internal back-up batteries

3 packs of 6 Alkaline batteries type R20 (size D) ≅ 45 Ah

On option Lithium (LSH20 from SAFT)

In standby mode, the backup battery packs offer 4 months for MT8x2 series and 30

months for ET8x2 series (with Alkaline batteries, 50 months with Lithium batteries).

In operation, the backup battery packs offer the following typical number of pulses

transmitted depending on Sound Power Level (SPL) and temperature (which applies

from hardware version 4.7) and two types of battery pack, see Table 3 and Table 4.

e 3 – Number of Chirps vs. Battery Types for MT8x2 Series

Tabl

SPL in dB ref 1µPa at 1m

185 dB 188 dB (default configuration) 191 dB

(5 sec. transmit rate)

Temperature (Celsius) 20°C 0°C 20°C 20°C

DL123A (DURACELL) 115,000 33,000

CR123A (VARTA) 40,000

47,000

53,000

21,000

Table 4 – Number of Chirps vs. Battery Types for ET8x2 Series

SPL in dB re. 1µPa at 1m

185 dB 188 dB (default configuration) 191 dB

(5 sec. transmit rate)

Temperature (Celsius) 20°C 0°C 20°C 20°C

Alkaline (Default configuration)

Lithium (LSH20)

1 300,000 350,000

2 300,000 700,000

550,000

900,000

250,000

410,000

Remote Transducer

Every iXBlue Acoustic Transponder with the letters "-HD" at the end of its designation

(e.g. MT 832 E-R-HD, see Figure 7) has a transducer separate from its body with this

arated transducer the transponder can be more easily installed on a underwater

sep

vehicle. It is also easier not to mask the acoustic transmission/reception head.

Figure 7 - Acoustic transponder MT 832 E–R-HD

MU-GAPS-AN-003 Ed. L – May 2012

Page 22

I.3.3.2 Acoustic Transponder BT812 Series

GAPS – User Guide

BT812 Special

Features

The technical features of the BT812 beacon are set in the factory and they are only

modifiable in the factory.

• The interrogation frequency is fixed to F2 (20 kHz)

• The Chirp Code can be 22 or 23

• Turn Around Time is 25 ms

• The Blanking Time is 260 ms

• The iXBlue BT 812 S is designed for a depth up to 700 m

The BT812 beacon can neither have a remote hydrophone nor operate in responder

mode. For more details, please refer to the BT812 User Guide.

I.3.4 INTEGRATED DGPS

The integrated DGPS has a WAAS / EGNOS / MSAS compatible active antenna. See the

coverage of the three Satellite Based Augmentation Systems on Figure 9.

Figure 8 - Int

egrated DGPS

Figure 9 – WAAS, EGNOS and MSAS coverage

MU-GAPS-AN-003 Ed. L – May 2012

Page 23

I.4 Conventions and Specifications

I.4.1 GENERAL CHARACTERISTICS

Positioning

Characteristics Values

Range depending on ambient noise and velocity 4,000 m

Coverage 200° below the acoustic array

Acoustic Level 192 +/-3 dB ref. 1 µPa/V

Operating frequency 22 to 30 kHz MFSK chirp modulation technique

Heading / Roll / Pitch accuracy needed 0.01°

Operating / Environment

GAPS – User Guide

Characteristic Value

Power supply / consumption 28 to 36 V DC / 35 W (45 W at starting up)

Operating temperature -5 °C to 35 °C

Storage temperature -20 °C to + 70 °C

I.4.2 GEOMETRICAL CONVENTIONS

Vessel

Attitude

The Figure 10 shows how the Roll, Pitch and Heading are measured on the ship and the

signs of these angles.

Figure 10 – Vessel Attitude Definition and Signs

MU-GAPS-AN-003 Ed. L – May 2012

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GAPS – User Guide

Hydrophones

The GAPS reference frame is based on the H1, H2, H3 and H4 hydrophones.

The hydrophones are numbered as follows (see Figure 11):

•

H1 is a short arm hydrophone, it is written H1 on it

• H2 is the short arm hydrophone located to the opposite of H1 short arm hydrophone

• H3 is the long arm hydrophone located on the right when H1 hydrophone faces you

• H4 is long arm hydrophone located to the opposite of H3 long arm hydrophone.

Reference

Axes

Figure 11 - H1, H2, H3 and, H4 hydrophones

The axes in the GAPS reference frame are as follows (see Figure 12 and Figure 13):

GAPS being in vertic

al position,

• H1 & H2: longitudinal axis (X) – H1 in front (positive)

• H3 & H4: transverse axis (Y) – H4 on starboard (positive)

• Z-axis positive towards the sea bottom

MU-GAPS-AN-003 Ed. L – May 2012

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GAPS – User Guide

Figure 12 - GAPS reference axes

Figure 13 - GAPS angular offsets

O INSURE COMPATIBILITY WITH OUR EXISTING SYSTEMS AND SOFTWARE, THE CONVENTION USED

FOR THE X AND Y AXES (SEE FIGURE 12 AND FIGURE

CONVENTION USUALLY USED

TO THE BOW, Y TO PORT, Z UPWARD

MU-GAPS-AN-003 Ed. L – May 2012

13)

MAY BE DIFFERENT FROM THE

Page 26

GAPS – User Guide

I.4.3 M

ECHANICAL SPECIFICATIONS

Characteristics Values

Housing Carbon

Weight in air / water 16 kg / -7 kg

Housing diameter x H (mm) 296 x 638 (fits in 12” gate valves)

Array depth-rating 25 m

Table 6 - Acoustic Array Cable 50 m (± 1.5m)

Connector SUBCONN on

GAPS side

Connector Souriau on ECB

side

Cable Diameter 15 mm

Table 5 - Acoustic Antenna

16 pins

diameter connector 26 mm

diameter locking sleeve 35.5 mm

diameter 26 mm

19 pins

Dynamic Bend Radius 150 mm

Static Bend Radius 75 mm

Breaking Strain 150 DaN

GAPS

CABLE IS NOT A TOW CABLE

MU-GAPS-AN-003 Ed. L – May 2012

Page 27

I.4.4 ELECTRICAL SPECIFICATIONS

GAPS – User Guide

Connection

You can find below a table describing the connections of all the 19-pins SOURIAU

connector (see Figure 14) connecting the main cable to the ECB (see Table 7).

OM OA OB

OL ON OP OC

OK OU OV OR OD

OT OS OE

OH OG OF

Figure 14 - 19 PINS Souriau socket (Ref. 851 06EC1419S50)

Table 7 - Association of the SOURIAU 19-pin, SUBCONN 16-pin and signals

MINI SUBCONN SOURIAU 851 Signal

PWR +

PWR GND

SYNCHRO IN +

SYNCHRO IN -

SYNCHRO OUT - RESPONDER MODE +

SYNCHRO OUT - RESPONDER MODE -

OPTIONAL EXTERNAL PRESSURE SENSOR IN RS 422 –Rx+

OPTIONAL EXTERNAL PRESSURE SENSOR IN RS 422 –Rx-

PRESSURE SENSOR WIRES SHIELD

MMI DIALOG INPUT – RS 422 –Rx+

MMI DIALOG INPUT – RS 422 –Rx-

MMI DIALOG OUTPUT – RS 422 –Tx+

MMI DIALOG OUTPUT – RS 422 –Tx-

MMI WIRES SHIELD

OPTIONAL EXTERNAL GPS MESSAGE INPUT – RS 422 –Rx+

OPTIONAL EXTERNAL GPS MESSAGE INPUT – RS 422 –Rx-

GPS WIRES SHIELD

STANDARD OUTPUT – RS 422 –Tx+

STANDARD OUTPUT – RS 422 –Tx-

MU-GAPS-AN-003 Ed. L – May 2012

Page 28

GAPS – User Guide

External

Power Supply

End User

System

GAPS must be electrically powered by a 28 to 36 V / 50W DC source. See Figure 15.

Figure 15 – 28 to 36 V power supply 3-pin SOURIAU plug

The whole system (GAPS+ECB+PC) must be powered by a 110-220 V / 50Hz source

(consumption: less than 50 W).

The positioning messages are available on the Standard Output RS 422 serial link (cable

output) or on the RS232 serial link (ECB output). These four DB9/RS232 ECB input/output

(Pressure IN, MMI IN and OUT, GPS IN, Output OUT) are used with straight cables.

Baud rate, parity and, bit stop are adjustable in the MMI Software (see Part IV of this

manual).

Control System

A RS422 or a RS232 (ECB) serial link is necessary to connect the MMI DIALOG link

(baud rate 57,600, parity odd and stop bit 2 are fixed).

MU-GAPS-AN-003 Ed. L – May 2012

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GAPS – User Guide

Responder

Mode

The SYNCHRO OUT – Responder mode signal is sent to the transponder if the responder

mode is activated. Two types of signal are available:

• A differential triggering signal is sent from the BNC of the front face of the ECB.

• A TTL triggering signal is sent from the BNC of the rear face of the ECB.

Table 8 – TTL and differential synchro out signals

Synchro OUT +

TTL Differential

0 / 5 V

Synchro OUT –

0 V

(Synchro OUT +) - (Synchro OUT –)

0 / 5 V

A TTL signal can independently trigger a TTL and differential input.

A differential signal cannot trigger a TTL input.

0 / 3.5 V

0 / -3.5 V

0 / 7 V

The simultaneous output of two different signals allows the independent triggering of both

MT8 and MT9 transponders (from all possible configurations).

Most of the time, these signals have to be re-amplified between GAPS and the

transponder. There can be a delay between the transmission of this signal by GAPS and

its reception by the transponder.

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GAPS – User Guide

The Table 9 below describes the compatibility between the different types and versions of

iXBlue transponders with the different versions of the ECB.

Table 9 – Compatibility between ECB and transponders

External

Synchro

ECB before 09/ 2010

ECB between 09/ 2010 and 01/ 2012

ECB after 01/ 2012

MT8

OK OK OK

OK NOK OK

MT9 before 02/2012 MT9 after 02/ 2012

OK rear of ECB

NOK front of ECB

F YOU ARE IN ONE OF THE SITUATIONS OF INCOMPATIBILITY DESCRIBED IN THE TABLE 9, CONTACT

IXBLUE TECHNICAL SUPPORT

The SYNCHRO IN (external) triggering signal is an active high pulse longer than 100 µs

(0 - 5 V). The GAPS is triggered on the rising edge.

The duration between two consecutive SYNC IN pulses must be greater than 1 s.

Electrical level Active High Length

External GPS

0 - 5 V

≥ 100 µs

If GAPS is triggered from the outside and in responder mode, with a transponder in

responder mode triggered on the sync IN input (the triggering pulse length must be higher

than 5 ms), the synchro shift between the recurrence and the transponder will last 1 s

maximum. For this reason, it is strongly recommended to trigger the transponder on the

Sync OUT.

If used, an external GPS has to be connected to the external optional GPS message input

RS 422 serial link or RS232 when using the ECB.

Baud rate (maximum 57,600 bauds), parity and bit stop are adjustable from the MMI

Software.

The message expected by GAPS is the standard NMEA $xxGGA message (see section

VI.1.1) and xxZDA (see section VI.1.2) is automatically taken into account for the update

of the GAPS i

nternal time if available. “xx” means that the first two letters of the format

name can be any letter.

MU-GAPS-AN-003 Ed. L – May 2012

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GAPS – User Guide

II I

NSTALLING

Before installing GAPS for the first time, it is recommended to check the contents of the

boxes delivered (see section II.1). The installation is achieved in four steps:

Installing the GAPS antenna, see section II.2

•

Installing the Easy Connect Box, see section II.3

•

Installing the DGPS Antenna, see section II.5

•

Installing a Transponder, see section II.6

GAPS

II.1 Checking of the Pack Contents

You have just received your equipment in protective boxes. Before starting the installation,

we recommend that you check the contents of the pack and the equipment

immediately on receipt of your GAPS System. Check that all items are present on

delivery and that none has been damaged during shipping.

Use the packing-list detailing all the shipped items. This packing list was compiled by

iXBlue shortly before shipment.

N RECEIPT OF THE EQUIPMENT, ITS OVERALL CONDITION SHOULD BE CHECKED AND IXBLUE

INFORMED OF ANY DAMAGE SUFFERED DURING SHIPPING. CHECK THAT EVERY PARCEL SHOCK

. I

LABEL IS STILL WHITE

INSURANCE COMPANY

EVER OPEN THE

N THE OPPOSITE CASE IT IS HIGHLY RECOMMENDED TO CONTACT THE

GAPS

UNIT

MU-GAPS-AN-003 Ed. L – May 2012

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II.2 Installing the Acoustic Antenna

GAPS – User Guide

II.2.1 R

ECOMMENDATIONS PRIOR TO INSTALLATION

Containing its own attitude sensor, GAPS can be installed at the location and in the

position that best suit the operational constraints.

Nevertheless, some factors concerning the installation can decrease the final global

performances of the system if they are not taken into account.

II.2.1.1 Noise Level

As with every acoustic system, the noise generated by the environment can decrease the

performance of the system. Range and accuracy of the positioning greatly depend on the

signal to noise ratio.

On a ship, it is recommended to install the GAPS unit in the front third of the ship (in order

to decrease the noise level from the propeller) and as far as possible from any water

discharge system.

II.2.1.2 Reflective Surfaces

Even though the MFSK signal treatment strongly increases the multi-path immunity, there

are still situations where the direct signal detection is disturbed by reflective signals.

To avoid such cases, it is recommended that GAPS is kept at least 1 m away from

reflective surfaces.

The sea surface may be considered as a reflective surface depending on the depth of the

transponder: if both the transponder and the acoustic array are close to the surface, there

will be multi-path phenomenon at specific distances.

The transponder depth is usually an operational constraint and therefore difficult to

change. In that case, it is recommended to increase the depth of GAPS.

For deep-water applications (more than 250 m), a depth of 1 m is usually enough for the

acoustic array. For more details about GAPS performances versus depth, see section

IV.1.

II.2.1.3 Corrosion

An electrical equipment which operates underwater like GAPS is submitted to differences

of potential that can lead to the corrosion of the mechanical structure of the antenna.

T IS YOUR RESPONSIBILITY TO MINIMIZE THE DIFFERENCES OF POTENTIAL BETWEEN THE

ANTENNA AND THE SURROUNDING STRUCTURES. THE

ELECTROLYTIC PROTECTION OF THE VESSEL

GAPS

ANTENNA MUST BENEFIT FROM THE

MU-GAPS-AN-003 Ed. L – May 2012

Page 33

GAPS – User Guide

Depending on the electrical installation of the different vessels (for example pole

connected to the ground or not), it is possible to change the ground configuration of the

GAPS in the ECB. This operation must be done by an iXBlue engineer, during the

installation of the equipment. See section II.4 for more details.

ONTACT IXBLUE TECHNICAL SUPPORT IF YOU NOTICE CORROSION DAMAGES ON THE EIGHT

II.2.2 I

Orientation

TITANIUM SCREWS HOLDING THE

THE PAINT FOR EXAMPLE

NSTALLATION PRINCIPLES

When you set up GAPS on the ship, the hydrophone H1 (see Figure 16) must be

oriented towards the bow. Positioning H1 towards the bow generates more drag but, in

this position, the acoustic noise is reduced.

GAPS

OR DIRECTLY ON THE ANTENNA HOUSING (BLISTERS OF

Insulation

Location

Mechanical

Plans

Figure 16 - GAPS H1 hydrophone location

In case GAPS is fixed on metallic plates of different materials (electro-chemical potential,

aluminum for example) it is necessary to electrically insulate it in order to avoid any

electro-galvanic reaction that will result in structure corrosion and GAPS acoustic array

fouling.

The location requirements for the GAPS antenna are listed below:

• There must be enough place for the wire way on the connector side of GAPS

• GAPS can be fixed using the eight M8 screws, however as there are several possible

deployments (see section II.2 for how to install your GAPS unit).

The me

chanical plan of the antenna is displayed on Figure 17.

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GAPS – User Guide

PAGE INTENTIONALLY LEFT BLANK

MU-GAPS-AN-003 Ed. L – May 2012

Page 35

GAPS – User Guide

Figure 17 – GAPS Mechanical Plan

MU-GAPS-AN-003 Ed. L – May 2012

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GAPS – User Guide

PAGE INTENTIONALLY LEFT BLANK

MU-GAPS-AN-003 Ed. L – May 2012

Page 37

II.2.3 DEPLOYMENT EXAMPLES

GAPS – User Guide

Figure 18- GAPS fixed on the hull and a transponder on a ROV

Figure 19 GAPS fixed on the hull and a transponder on a tow fish

MU-GAPS-AN-003 Ed. L – May 2012

Page 38

Figure 20 - GAPS mounted under a tripod

GAPS – User Guide

Figure 21 - Transponder fixed on a scuba cylinder

Figure 22 – GAPS inside a hoisting pool

MU-GAPS-AN-003 Ed. L – May 2012

Page 39

GAPS – User Guide

Figure 23 - Different installations on a pole, underneath the keel or in a moon pool

MU-GAPS-AN-003 Ed. L – May 2012

Page 40

II.3 Installing the Easy Connect Box

The connections between the different devices can be set up through the iXBlue junction

box called ‘Easy Connect Box’ (ECB). See Figure 24. Through the Easy Connect Box, you

set up all connections between the different devices of the system.

can

GAPS – User Guide

Figure 24- GAPS System Architecture

MU-GAPS-AN-003 Ed. L – May 2012

Page 41

GAPS – User Guide

Figure 25 - ECB Box, Front Face and Back Face

II.3.1 CONNECTIONS ON THE FRONT FACE

From left to right (see Figure 25):

• BNC SYNC OUT plug with its status light triggers the transponder in responder mode

with a differential signal

• Power status light for ECB (ON/OFF switch on the back)

• ON/OFF switch for GAPS with its status light

II.3.2 CONNECTIONS ON THE BACK FACE

From left to right (see Figure 25):

• 2 BNC plugs for

 SYNC OUT to trigger the transponder in responder mode with a TTL signal

 SYNC IN GAPS acoustic recurrence triggered by an external device (side-scan

sonar for example)

• 4 DB9 plugs for RS232 Serial Links (use of straight cables)

 Input connection to the PRESSURE sensor, the input configuration of which

being Baud rate = 19200 bps, Data Bits = 8, Parity = none, Stop Bit =1

Note: 10 dBar correspond to 0 m and 20 dBar correspond to 10 m depth.

 OUTPUT of position and attitude available in various formats

 Input/output MMI connection to the user PC for configuration and real-time

control

MU-GAPS-AN-003 Ed. L – May 2012

Page 42

GAPS – User Guide



Input GPS connection to an external GPS receiver

• The GAPS 19-pin plug for the Acoustic Array cable

• The 28 to 36 V - 50W DC (2A) ECB power supply plug

• The 100 to 240 V, 50-60Hz ECB power supply plug, automatically detected, no

adaptation needed

• The ON/OFF switch for ECB

Both 100 – 240 V and 28 – 36 VDC ECB power supply inputs can be connected

simultaneously. The 100 – 240 V is converted into 28 VDC. The ECB automatically

switches on the highest voltage input between the 100 – 240 V converted and the 28 – 36

The ECB is supplied with a female connector on which can be welded a 28 – 36 VDC

power supply cable of your own. See the connector in Figure 26.

Figure 26 – Female Connector for ECB 28 – 36 VDC Power Supply

MU-GAPS-AN-003 Ed. L – May 2012

Page 43

II.4 Checking the Electrical Ground Continuity

You must ensure that the electrical installation is correct in order to prevent the antenna

from corrosion. Before proceeding to the test, please make sure that you have:

• Installed the GAPS acoustic antenna

• Installed and powered the ECB

• Connected the cable between the ECB and the acoustic antenna

The test consists in measuring the voltage between the GAPS antenna and the hull of the

ship with a multitester.

Procedure

Step Action

Put the first probe of the multitester on a conductive part of the housing of the GAPS

antenna. It can be the transducer titanium plate or the titanium screws.

GAPS – User Guide

Put the second probe on a conductive part of the ship hull.

Read the voltage between these two points.

The voltage must be below 1.0 V.

End of procedure.

If the voltage between the GAPS antenna and the hull of the ship is below 1.0 V, the

system is electrically well installed.

F THE VOLTAGE BETWEEN THE

1.0 V,

CORROSION WILL IMPACT YOUR SYSTEM. A MODIFICATION MUST BE MADE IN THE

CHANGE THE ELECTRICAL GROUND CONFIGURATION

ONTACT IXBLUE TECHNICAL SUPPORT. SEE COORDINATES PAGE

GAPS

ANTENNA AND THE HULL OF THE SHIP IS GREATER THAN

. T

O DO SO

MU-GAPS-AN-003 Ed. L – May 2012

133.

ECB

Page 44

II.5 Installing the GPS Antenna

The integrated DGPS antenna has to be fixed (see Figure 27). You can use a mast (not

provided) to do it.

GAPS – User Guide

Figure 27 - DGPS antenna installation

Two configurations are possible:

• With the ship GPS (see config. 1 on Figure 24)

With the DGPS provided by iXBlue (see config. 2 on Figure 24)

•

II.5.1 INSTALLING AN EXTERNAL GPS

In this case, you must not use the Y-cable to be plugged to the GAPS. Plug your GPS

directly on the ECB via the GPS DB9 plug or on your Souriau socket of your acoustic

array cable if you do not use an ECB.

II.5.2 INSTALLING THE IXBLUE DGPS

The DGPS DB9 plug of the ECB is not used in this case. Plug the 10 m GPS cable on the

Y-cable then the DGPS.

MU-GAPS-AN-003 Ed. L – May 2012

Page 45

II.5.3 MEASURING THE GPS LEVER ARMS

GAPS – User Guide

GPS Antenna

Lever Arms

GPS Antenna

Above GAPS

Even though it is designed to work in the vertical position, GAPS acoustic array can be

tilted if necessary and also be placed in the horizontal position.

To calculate the absolute position of a transponder, GAPS needs to know its own position.

This information is provided by the GPS, either the integrated or an external one. In both

cases, the offsets between the GPS antenna and the GAPS acoustic array must be

known.

When GAPS is tilted, the three offsets between the GPS antenna and the acoustic array

have to be entered accurately. When GAPS is in horizontal position, the axes are

inverted, the attitude outputs are then irrelevant.

There are 2 different solutions to install the GPS antenna with different implications on the

mounting of the acoustic array:

• GPS antenna right above GAPS

• GPS antenna not exactly above GAPS

Connected with a Rigid Link

This is typically when GAPS is mounted on a mast or held by a rigid pole.

When GAPS is vertical, all the offsets between the GPS antenna and the acoustic array

are set to 0 except the height (h) which must be entered accurately in order to calculate

the position offset when the system attitude changes.

Figure 28 - Vertical GPS Antenna Lever Arm

MU-GAPS-AN-003 Ed. L – May 2012

Page 46

GAPS – User Guide

Connected with a flexible link

This is typically when GAPS is held by a rope.

In that case, the height value (h) must also be set to 0 (to avoid the calculation of the

offset). The accuracy of the positioning will decrease if the position of GAPS relative to the

GPS antenna changes.

GPS antenna

not above

GAPS

Figure 29 - Vertical GPS Antenna Lever Arm

When the GPS antenna is not located right above GAPS, its position in the GAPS frame

has to be determined. The definition of these lever arms, Xgps, Ygps and, Zgps is given

in Figure 30.

Figure 30 -

GPS antenna Lever Arms (antenna not above GAPS)

MU-GAPS-AN-003 Ed. L – May 2012

Page 47

GAPS – User Guide

In this case, the heading of the acoustic array must be fixed and known. No matter if this

heading is not the same as that of the ship (yet it will have to be taken into account if

GAPS is also used as an onboard gyrocompass), but its value must be known in order to

calculate the position of the GPS in the GAPS reference frame (see Figure 31).

GAPS

GPS

Figure 31 - Same headings (on the left) and different headings (on the right) for GAPS and ship

• If the GAPS H1-H2 axis is not parallel to the ship aft forward axis, two options are

possible to enter the GPS offsets with respect to the GAPS reference system:

• Enter the offset distances of the GPS with respect to the ship reference system shifted

above the GAPS antenna. Then enter the angular offsets of the GAPS reference

system with respect to the ship reference system using the antenna offsets tool box

window.

NTER THE OBSERVED OFFSETS VALUES AND NOT THE CORRECTION TO BRING TO THE OFFSETS

• Enter the distances offsets of the GPS antenna directly in the tilted GAPS reference

system

The closer GAPS is to the GPS, the better is the accuracy of the measurement of the

heading of the acoustic array.

It is the same for the roll and pitch if the GAPS is intentionally not in the vertical position.

Measure the position of the GPS reference point with respect to the reference frame

linked to the GAPS unit. Measurement is performed along the three axis Xgps, Ygps,

Zgps (see section I.4.2 for the definition of the GAPS reference frame).

quired precision on the lever arm is below 10 cm. See Figure 32.

The re

MU-GAPS-AN-003 Ed. L – May 2012

Page 48

Figure 32 – Measure of GPS lever arms with respect to GAPS

GAPS – User Guide

II.5.4 SETTING THE GPS TIME

GAPS automatically updates its internal time. No menu in the MMI software enables you

to do it. Two cases can occur:

• Either the GPS is used as a reference. In this case, the GPS must be configured in

order to send ZDA frame (with a minimum rate of 1 s). As no PPS signal is used, the

precision reached is equal to ± 15 ms after the PPS signal

• Or if no ZDA frame is received by GAPS, the last time recorded by GAPS is used.

If the GPS do not deliver ZDA strings, then the time is taken from the GGA strings and the

precision of the positioning is still less than 1 second.

II.6 Installing a Transponder

The transponder is installed on the fixed or the mobile device that you are going to track.

The installation depends mainly on your equipment. Keep in mind that the transponder

head must be as much as possible

• Free from obstacles

• Directed towards the hydrophones of the GAPS antenna.

See installation examples in section II.2.3.

See se

ction IV.2.4 to bring the transponder in operation.

MU-GAPS-AN-003 Ed. L – May 2012

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GAPS – User Guide

III C

ONFIGURING

GAPS System is controlled by a user PC on which the Man Machine Interface software is

installed. All its functionalities are described in this section.

GAPS

III.1 Installing the Man Machine Interface

Required

environment

To set GAPS, the Man Machine Interface software provided with the system must be

installed on a PC.

The minimum PC configuration must be:

• Pentium III or Celeron 800 MHz

• 512 Mo RAM

• 20 Mb Hard Disk

• 1024 x 768 screen (the screen must be configured with a character size of 96 ppp)

• Microsoft Windows ™XP, VISTA and SEVEN

The installation of the Man Machine Interface cannot be achieved elsewhere than in the

Procedure

Step Action

C:/Program Files/IXSEA folder. In foreign versions of the operating system, the

C:/Program Files folder may not exist. Please make sure to create it before running

the installation procedure.

Insert the MMI software CD-ROM in the CD-ROM drive.

The installation should start automatically otherwise double click on Setup in the CD-

ROM directory.

Follow the instructions displayed on screen.

Once the installation is completed, an IXSEA\GAPS MMI directory is created in the

default file C:/program files on your computer.

End of procedure.

On Windows SEVEN and VISTA, make sure to edit the security properties of the iXSea

folder and all sub-folders so writing in these folders is allowed.

MU-GAPS-AN-003 Ed. L – May 2012

Page 50

III.2 Overview of the Man Machine Interface

III.2.1 STARTING THE MAN MACHINE INTERFACE

Once the MMI installation is completed and when you have achieved all connections

between the devices, you can start the MMI Software.

GAPS – User Guide

Procedure

Step Action

Figure 33 – Starting GAPS MMI, launching window

From Start menu, select Programs/ GAPS MMI/Man Machine Interface Software.

The MMI is started. The Communication ports of the PC are scanned by MMI to

recognize which devices are connected.

• If GAPS is not connected, the following window appears:

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Step Action

• Otherwise, if GAPS is connected and if both configurations between GAPS and

the MMI are different, the following dialog box appears:

In this case, you can know for which parameters the configurations differ by clicking on

Details button:

GAPS – User Guide

• Otherwise, if GAPS is connected and if the configurations of the GAPS and the

MMI are the same, the following window appears:

If needed, choose between the MMI or GAPS configuration.

• If GAPS is not active, the system button located in the upper right side of the

main window is labeled ‘START Tracking’ and the associated light is blue

• If GAPS is active, the system button located in the upper right side of the main

window is labeled ‘STOP Tracking’ and the associated light is green

End of procedure.

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III.2.2 MAIN WINDOW

MMI software always opens with Vessel tab selected under the Mission menu (see

Figure 34).

GAPS – User Guide

Figure 34 - M

ain MMI Window

This main MMI window is divided into four areas:

• Menu bar: it enables to access the main menus and Help file.

 Mission menu: it enables to configure the system and the interface

parameters (see section III.3.2) and, to enter the sound velocity profiles (see

ction III.3.9)

 Views menu: to display the real time data either in a geographic reference

frame (see section Figure 44), or in a ship dependent frame (see Figure 45) or

in a time-de

 Transponder menu: to add, define, modify and, suppress the devices you are

pth frame (see Figure 46)

tracking with GAPS (see section III.3.10)

The Tool Boxes area: these boxes enable you to monitor your mission.

•

 System box: see section III.4.5 for more details.

 Sensors box: see section III.4.5 for more details.

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GAPS – User Guide



Recorder box: it enables to select the folder where the real time data will be

stored (see section III.5).



Tool Box: the content of this box depends on the selected menu and/or on the

selections made in the above boxes.

• Control buttons



Valid button: to validate the modifications entered and to save them in the

GAPS.



Cancel button: to cancel the modification you have entered.

• Display area: The display area is menu dependent. It can display vessel parameters

(see section III.3.2), real time data display (see section III.4.1), sound velocity profile

e section III.3.9) etc.

(se

III.2.3 C

OLOR CODE

When you modify some parameters in the different windows or toolboxes, the

corresponding menu titles are set to red. This color code means that modifications have

been made but not applied yet in the MMI and/or GAPS itself. Use the Valid button to

apply them.

UNCTIONAL PARAMETERS CANNOT BE VALIDATED WHEN

MODIFY FUNCTIONAL PARAMETERS WHILE

.G., ‘STOP

OU HAVE TO STOP TRACKING BEFORE APPLYING THE MODIFICATIONS

TRACKING’ LABEL, DISPLAYS A RED CONTOUR AND IT IS FLASHING

GAPS

IS OPERATING, THE COMMUNICATION BUTTON

GAPS

IS OPERATING. WHEN YOU

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III.3 Configuring GAPS

GAPS – User Guide

III.3.1 C

Window

Access

Parameters

ONFIGURING THE SURVEY PARAMETERS

Before running the survey, you have to define the mission parameters.

To configure and/or modify the mission parameters, select the Vessel tab under the

Mission menu.

In the displayed window (see Figure 35 and Figure 36), you have to define:

•

In the associated tool box:



The Vessel Name and color for the real time data is displayed. This setting is

optional.



The Mission Name. This setting is optional.



The angular offsets of the GAPS called antenna offsets (Heading, Roll and

Pitch). Normally GAPS must be in vertical position and oriented so that the

hydrophone H1 is towards the bow (see Part 2 of this manual). In such a

configuration, the angular offsets are set to zero. If GAPS is tilted so that the

angles are greater than a few degrees then you have to enter these angular

offset.

RICK TO DETERMINE THE ANGULAR OFFSETS

HEN THE SHIP IS AT A 0° HEADING, 0° ROLL AND 0° PITCH, THE VALUES AND SIGNS OF THE

ANGULAR OFFSETS CAN BE FOUND IN THE

IEWS WINDOWS IN THE ATTITUDE FIELDS

• In the Display area, the following values are only used in the relative views. They do

not affect positioning.



The vessel dimensions: the Length, Height and Width values (only used in

the relative views)



The location of the ship stern and port side with respect to GAPS: Stern (Xp),

Port (Yp).

Example: For a GAPS located at the stern level at 2 m of the port side (inside the ship),

these values are the following:

Xp = 0 m , Yp = -2 m

Figure 35 - Position of the stern port point with respect to GAPS

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GAPS – User Guide

 The lever arms of the GPS antenna with respect to GAPS: Longitudinal (X),

Transverse (Y), Vertical (Z) values. These parameters affect directly the

positioning. The further the GPS is from GAPS, the bigger the error in the lever

arms will be. See Figure 37 for numerical examples.

 The draft D of the ship relative to GAPS.

Figure 36 - Vessel Window

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GAPS – User Guide

Figure 37 – Examples of Numerical values for the ship dimensions and the GPS offsets with respect to GAPS

All offsets and distances are in meters and signed with respect to the axis drawn in the

window.

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Procedure

Step Action

GAPS – User Guide

In the Vessel Dimensions display area, fill in the vessel dimensions by clicking on the

corresponding fields.

When you click on a distance field that you want to fill, the style of the associated line in

the ship representation below is highlighted in order to be easily identified and to avoid

confusion between distances.

The drawing of the vessel window does not change. The Vessel tab label turns red.

In the Stern and Port side coord. Relative to GAPS display area, fill in the ship port

side and stern with respect to GAPS by clicking on the corresponding fields.

When you click on Xp or Yp field that you want to fill, the style of the associated line in

the ship representation below is highlighted in order to be identified and avoid confusion.

In the relative view, the reference frame corresponds exactly to the position of GAPS

with respect to the ship.

In the GPS Antenna relative to GAPS lever arms display area, fill in the GPS lever

arms by clicking on the corresponding fields.

When you click on a lever arm field that you want to fill, the style of the associated line in

the ship representation below is highlighted in order to be easily identified and to avoid

confusion between lever arms.

In the Depth display area, fill in the depth of the antenna by clicking on the D field.

In the associated tool box, enter the following optional parameters

• The Vessel Name

The entered vessel name will appear in the different available views.

• In the associated toolbox, click on the color button to choose the color of

the symbol representing the vessel in the real-time data displays.

A color palette is displayed.

• The Mission Name

The mission name appears in the window title.

Enter the GAPS angular offsets: Heading, Roll and Pitch. All values are expressed in

degrees.

Click Valid button to validate the modifications if GAPS is not operating otherwise stop

GAPS before clicking the Valid button.

End of procedure.

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III.3.2 CONFIGURING THE SYSTEM PARAMETERS

Before running the survey, you have to define all the parameters of the different interfaces

of GAPS, MMI software, serial link, GPS, Inertial sensor, processor, acoustic array and

output.

GAPS – User Guide

Window

Access

Version

Choice

Parameters

To configure and/or modify the GAPS System parameters, select the Supervision tab

under the Mission menu.

When the MMI is not connected to a GAPS unit, two radio buttons appear on the right of

the antenna display. These two radio buttons allow the user to select the GAPS version:

• Titanium Version V

and V2: not described in this document.

• Carbon Version: this system is described in the present manual.

When the MMI is connected to a GAPS unit, the MMI software switches automatically

between the two versions.

In the displayed window (see Figure 38), you can configure or display:

The MMI serial link parameters: port number, baud rate (maximum 57,600 bauds),

•

parity, stop bit

• The MMI parameters: alarm sound and automatic recording of data files

• The GPS parameters: baud rate (maximum 57,600 bauds), protocol, parity and, stop

bit

• The processor parameters: position rate delivery and acoustic recurrence

• The acoustic array parameters: Interrogation Frequency, Signal/Noise Ratio

parameters

• The output parameters: protocol (which kind of data are delivered), period, Baud rate

(maximum 57,600 bauds), Parity, Stop bit

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GAPS – User Guide

Figure 38 - Supervision Window

In the Supervision window, the Tool Box displays some versions about the system

components: MMI software version, CPU version, 4Ways version and INS version.

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III.3.3 CONFIGURING THE SERIAL LINK

Step Action

In the Supervision display area (see Figure 38), click on Serial Link label.

The associated tool box appears.

In the associated toolbox, you can reload in GAPS the configuration displayed in MMI by

clicking on GAPS Configuration.

The serial link parameters already saved are then displayed.

In the Tool Box, if necessary

• Choose the Port number by selecting it in the scrolling list

• Only on iXBlue customer support request, choose the Position Protocol: GAPS

Extended (only for factory usage). By default, it is the protocol GAPS Regular

that it is used.

GAPS – User Guide

In the Display area, the Serial Link label turns red to remind you that you have to

validate your choices.

Click Valid button to validate the modifications if GAPS is not operating otherwise stop

GAPS before clicking the Valid button.

End of procedure.

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III.3.4 CONFIGURING THE INTERFACE PARAMETERS

Step Action

In the Supervision display area (see Figure 38), click on MMI label.

GAPS – User Guide

The asso

In the tool box, if needed

ciated tool box appears.

• Choose to be informed by a sound when any status light of the sensor tool box

becomes red: select the Alarm Sound check box.

• Choose to record automatically the real time data: select Automatic Recording

check box.

In the Display area, the MMI label turns red to remind you that you have to validate your

choices.

Click Valid button to validate the modifications if GAPS is not operating otherwise stop

GAPS before clicking the Valid button.

End of procedure.

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III.3.5 CONFIGURING THE GPS PARAMETERS

Step Action

In the Supervision display area (see Figure 38), click on GPS label.

GAPS – User Guide

The asso

In the Tool Box, choose

ciated tool box appears.

• The baud rate by selecting it in the scrolling list (maximum 57,600 bauds)

• The Parity and Stop Bit by selecting them in the corresponding scrolling lists.

In the Display area, the GPS label turns red to remind you that you have to validate your

choices.

Click Valid button to validate the modifications if GAPS is not operating otherwise stop

GAPS before clicking the Valid button.

End of procedure.

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III.3.6 CONFIGURING THE PROCESSOR PARAMETERS

You can choose the rate of the acoustic ping and the types of acoustic mode:

• Internal Fixed – it needs to set up the recurrence in the edit box at the bottom of the

dialog box. The minimum value is 1 s. The recurrence obey the following inequalities:

R +> 1*



max

TAT

in responder mode

500,1

R +> 2*



max

TAT

in transponder mode

500,1

GAPS – User Guide

R is the recurrence, D

and TAT is the turn around time. See Table 10.

Table 10 – Maximum worki

Maximum working distance (m)

Responder mode Transponder mode

1 1,365 682

2 2,865 1,432

3 4,365 2,182

4 5,865 2,932

5 7,365 3,682

Recurrence (s)

6 8,865 4,432

is the distance between the antenna and the transponder

max

ng distance versus recurrence with a TAT = 90 ms

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Procedure

Step Action

GAPS – User Guide

• External – coming from the synchro IN. The recurrence used may be slow. It must

always be greater than 1 s. When the position cycle is lower than the acoustic

recurrence, the INS helped with the GPS predicts the points between two pulses.

In the Supervision display area (see Figure 38), click on Pr

In the Tool Box, if needed

• Enter the delivery rate in Recurrence in [second] if Internal Fixed is selected.

ocessor label:

• Otherwise choose External.

In the Display area, the Processor label turns red.

Click on Valid if GAPS is not operating otherwise stop GAPS before clicking on Valid.

End of procedure.

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III.3.7 CONFIGURING THE ACOUSTIC ARRAY PARAMETERS

There is no configuration to perform for the antenna, however there is the opportunity to

check the NIS (Noise Isotropic Spectrum) on each hydrophone of the antenna. It gives an

idea of the current acoustic noise in the sea and allows to quickly find out if a hydrophone

is damaged.

Step Action

In the display area, click on Acoustic Array label.

The associated tool box appears.

GAPS – User Guide

The Interrogation frequency used is displayed according to the transponder

configurations.

Check the NIS on each hydrophone. Verify that the given values are homogeneous. In

the opposite, the hydrophone giving a strongly different value than the others is probably

faulty.

End of procedure.

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III.3.8 CONFIGURING THE OUTPUT PARAMETERS

In this toolbox can be set up the parameters of the additional output data: which kind of

data and the associated port configuration.

The list of protocols available is (“none” means no Output):

For the string containing the transponder position:

• GAPS Standard

• GAPS Light

• HiPap HPR 418 BCD (Rev C) Mobile

• HiPap HPR 418 BCD (Rev C) Fixed

• HiPap HPR 400

• Nautronix ATS II

• POSIDONIA 6000

• IXSEA USBL-INS 1

• IXSEA USBL-INS 2

GAPS – User Guide

• GPGGA (GAPS antenna) + VTG

For the strings containing information relative to the GAPS antenna but NO position of the

transponder:

• GyroCompass

• Halliburton

• Navigation

• HEHDT

• Phins Standard

• Simrad EM

• Autosub

• Post processing (for factory use only)

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Procedure

Step Action

GAPS – User Guide

In the Supervision display area (see Figure 38), click on Ou

tput label.

The associated tool box appears.

• Choose the Protocol by selecting it in the scrolling list

• Enter the real time data Period in [ms] (see Note below)

• Choose the Baud rate by selecting it in the scrolling list (maximum 57600 bauds)

• Choose the Parity and Stop bit by selecting them in the scrolling lists.

In the Display area, the Output label turns red to remind you to validate your choices.

Click Valid button to validate the modifications if GAPS is not operating otherwise stop

GAPS before clicking the Valid button.

End of procedure.

If you select a protocol that uses raw positions (such POSIDONIA 6000, IXSEA USBL INS

1, IXSEA USBL INS 2), the position rate cannot be set as it is the rate of these raw

positions that applies. In this case, the field Period has no meaning.

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III.3.9 DEFINING A SOUND VELOCITY PROFILE

GAPS – User Guide

Entering a

Velocity

Profile

Window

Access

To compute the transponder position, the ray bending has to be taken into account. A

sound velocity profile (SVP) must be defined.

You can either manually enter (point by point) the velocity values (between 1400 and

1600 m/s) with respect to immersions or import a sound velocity profile file. In this case,

the file must be a list of

Immersion depth (integer in [meter]), Celerity (integer in [m/s])

comma separated [CR/LF]

e.g., ‘2000,1500’ (At 2,000 meters depth the sound velocity is 1500 m/s)

in a text format. Imperatively, this file must contain a maximum of 55 couples (depth,

celerity) classified in increasing depths. If there are more than 55 data, the last ones are

lost.

The immersion depths can be modified manually in the file. The immersion depths are

transformed into pressure values by the MMI before transmitting them to the GAPS.

The first depth value must be ‘0’. The last depth value cannot be greater than 7,000.

This input file or the manually input points can be saved in another file.

To enter a sound velocity profile, select the S/Velocity tab under the Mission menu.

Window

Description

The corresponding window (see Figure 39) appears. The Sound Velocity Profile and Ray

Bending a

reas may be empty if you have not defined a sound velocity profile yet.

Figure 39 - Sound Velocity View Window

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Manually Entering a Sound Velocity Profile

Step Action

Select the S/Velocity tab under Mission menu in the toolbox (see Figure 40), type in the

GAPS – User Guide

S.Velocit

y value for each immersion depth appearing in the Depth field. Validate each

sound velocity input by pressing the [enter] key.

The sound velocity profile updates at each input. The depth value increments and you

are ready to enter the sound velocity corresponding to the next depth value.

You can save the profile you have defined in step 1. by clicking on button.

The Save as window appears.

Choose the folder where you want to save the sound velocity profile, type in the filename

and click OK.

Your sound velocity profile is saved in a text file with the format described above.

Click Valid button to validate the modifications if GAPS is not operating otherwise stop

GAPS before clicking the Valid button.

End of procedure.

Figure 40 – Sound Velocity Toolbox

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Importing a Sound Velocity Profile File

Step Action

Select the S/Velocity tab under Mission menu in the toolbox (see Figure 40), click on

button to import a file.

GAPS – User Guide

Looking for

Shadows

Areas

The Ope

Select your sound velocity profile file and click OK.

n… window appears.

The sound velocity profile appears in the Display area.

You can modify some sound velocity values (see the previous procedure) and then save

the modified file under the same name (by clicking ) or under another one (by

clicking on )

Your sound velocity profile is modified.

Click Valid button to validate the modifications if GAPS is not operating otherwise stop

GAPS before clicking the Valid button.

End of procedure.

Once the velocity profile is input, you can compute, by double clicking on the right graph,

the path that a sound ray would take with this velocity profile. The graph is computed for

angles between 0° and 90° at a 1° step. The path is computed from the GAPS to the

Zooming

III.3.10 C

Defining a

Transponder

transponder. This allows you to see if there are areas where you could not see your

mobile (shadow areas, see Figure 39). Note that the horizontal an

d vertical scales are not

the same when looking at angles on the graph. You can zoom on the data by drawing a

rectangle with the left mouse button down over the area of your choice.

You can zoom on the area of your choice on the graph. Left-click on one of the graphs

and draw a rectangle. Double click to come back to the full visualization.

ONFIGURING THE TRANSPONDER PARAMETERS

You can add a new transponder from a list or copy the settings of a transponder already in

defined to the new one being entered. The available transponders are iXBlue–MT8 or

ET8, iXBlue-MT9, iXBlue-BT8, ORE-435xB.

HE IXBLUE

ELECT AN IXBLUE

PARAMETERS AVAILABLE FOR THE

-MT9

IS CONFIGURED VIA THE CONFIGURATION WINDOW OF THE IXBLUE

-MT8

TRANSPONDER IN ORDER TO ADD A IXBLUE

MT8

ARE APPLIED TO YOUR

-MT9. T

MT9

TRANSPONDER

HE CONFIGURATION

-MT8.

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GAPS – User Guide

Access

The creation process of a new transponder displays successively two different windows:

• The New transponder window (see Figure 41): access it by selecting Ne

w… option

under Transponders menu

• The transponder view in the Display area of the Main MMI window:

• See Figure 41 for a multi-frequency transponder: access it once you have clicked

Crea

te button in the New Transponder window.

These windows contain:

• New Transponder window: It contains the transponder ID, its Manufacturer and

Type to define. You can copy the settings of an existing transponder to create a new

one by selecting Copy from check box and selecting its ID. The transponder ID is the

main transponder identifier in the MMI.

• Transponder view: The tool box enables you to set the transponder in the ‘in use’

state (i.e. to display it in the different views), to choose its display color for the

absolute, relative and depth view and, to know and possibly modify its serial number,

ID one and name. The display area contains:



The Transmit parameters are used to define the MFSK code, the Blanking

Time i.e., the time during which no transmission is possible just after having

transmitted and, the Turn around Time i.e., the delay between the reception

of the triggering signal and the transmission of the reply.



The Receive parameters are used to define the Individual Interrogation

Frequency (IIF) and if the transponder is used in Responder or Transponder

mode (see Part 1 of this manual).



Filtering for is used to define the filter to use: None, Towed Fish (specific

filter adapted to mobiles, predictable motion), ROV/AUV (specific filter adapted

to mobiles, unpredictable motion), Fixed Transponder (specific filter adapted

to fixed transponders, no motion).



Pressure sensor: None, Serial link, Acoustic or External with the accuracy

in decimeter (for example for a pressure sensor given for 0.1% of the depth

that would be used at a 3,000 m – depth, you would enter 30 dm in the

accuracy field).

You can define up to 127 transponders.

HE TRANSPONDER CAN BE TRACKED ONLY WHEN IT IS ‘IN USE’.

OU CANNOT USE TWO (OR MORE) TRANSPONDERS WITH THE SAME

SIMULTANEOUSLY

IIF

AND

MFSK

CODE

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Page 72

GAPS – User Guide

Figure 41 - Transponder MT8 view

Figure 42 - Transponder BT8 view

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Page 73

Procedure

Step Action

GAPS – User Guide

Under Transponders menu select New… option to define the new transponder.

The New Transponder window opens:

In the New transponder window, you can

• Either select the Manufacturer and Type after having selected New check box.

• Or define the new settings by selecting existing ones: select Copy from check box

and choose the transponder ID to copy in the scrolling list.

Click Create button to create the new transponder.

The transponder settings are displayed in the Display area of the main MMI window. It

contains default settings for a new transponder and the settings of an existing one in

case of a copy.

The transponder ID appears in the transponder list (near the Transponders menu).

You can

• Modify the settings

• Change the transponder display color by clicking on

Select In Use check box to track the transponder and to see this transponder in the

different views.

The transponder ID in the transponders list (near the Transponders menu) turns red

and a “.” appears after the transponder ID number in the transponder menu:

Click on Valid if GAPS is not operating otherwise stop GAPS before clicking on Valid.

The transponder ID in the list (besides the Transponders menu) turns black.

End of procedure.

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GAPS – User Guide

Checking/

Editing

Step Action

Suppressing

Step Action

• If its ID is displayed in the Transponder list near the Transponders menu, click on it.

• Otherwise scroll in the ID number using the or button to find it and then select

it by clicking. On its ID number.

• Or use the Go to box to enter directly its ID.

End of procedure.

Select Suppress… option in the Transponders menu.

The Transponder deletion window appears:

Sorting

Select the transponder you want to delete in the Delete Transponder scrolling list and

click Delete.

The transponder ID disappears from the transponder list near the Transponders menu.

End of procedure.

The transponder cannot be deleted when “in use” and /or when GAPS is tracking.

You can sort the transponders list by chronological or numerical order by selecting

Chronological list or Numerical list (on the ID) in the Transponders menu.

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GAPS – User Guide

Swapping

Step Action

To exchange the characteristics of two transponders: their IDs remain unchanged but all

their characteristics are exchanged.

Select Swap… option of the Transponders menu.

The Configuration Swap window appears:

Select the two ID transponders you want to exchange and click OK.

The transponder IDs turn red in the transponder list.

Edit one of the swapped transponders.

Click Valid button to validate the modifications if GAPS is not operating otherwise stop

GAPS before clicking the Valid button.

The transponder ID in the transponders list (near the Transponders menu) turns black.

Edit the other swapped transponder.

Click Valid button to validate the modifications if GAPS is not operating otherwise stop

GAPS before clicking the Valid button.

The transponder ID in the transponders list (near the Transponders menu) turns black.

End of procedure.

Only the not ‘In Use’ transponders can be swapped.

Do not forget to check ‘In Use’ check box if necessary after swapping.

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III.4 Monitoring the GAPS in Operation

III.4.1 CONTROLLING THE REAL TIME DATA

To control the real time data, the MMI software offers three kinds of view:

• The absolute view: it is a geographic mode, in which you can see all the mobiles

evolving together

• The relative view: it is fixed on the ship. You can visualize the motion of the mobiles

relative to the ship

• The depth view: it shows the mobile depths relative to time

All these three views have a common area: the Parameter Display area located top of the

Display area (see Figure 43).

GAPS – User Guide

Figure 43 - P

In this Parameter Display area, you can select

• From the upper left part: a mobile (vessel or transponder), the displayed fields are

fixed and depend on your mobile choice.

• From the upper middle part:

 The mobiles of which you want to visualize the parameters,

 The parameters to visualize for each mobile.

arameter Display Area (Absolute view case)

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Page 77

Once selected, you can visualize them by clicking on Display Selection button below.

The parameters of four mobiles including the vessel can be visualized at the same time.

You can select and display the following parameters:

 For the vessel: latitude, longitude, speed, heading, roll, pitch, noise

 For the transponders: latitude, longitude, X, Y, Z, pressure sensor, Vertical

Angle, Bearing, Horizontal Distance, Slant Range, Signal To Noise Ratio.

For all views, you can visualize the parameters of up to four transponders simultaneously

including the vessel.

III.4.2 VISUALIZING WITH THE ABSOLUTE VIEW

GAPS – User Guide

Window

Access

Window

To display the real time data in a geographic display, select Absolute tab under the

Views menu.

The corresponding window (see Figure 44) appears.

Figure 44 - A

bsolute view

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GAPS – User Guide

The Tool Box contains the following parameters:

• Auto Scale, (full extent, grid limits are set in order to view all data in graph) applied to

selected mobile in the bow below.

• Auto Frame, (when the selected mobile crosses the grid limits these limits are

updated) applied to the selected mobile in the bow below:

 Check this box: a cross-mark appears in the Vessel box

 Then click on the box of the selected mobile (for example, in the of the fish

mobile in the Figure 44): the cross-mark is now displayed in the box of the

selected mobile.

•

The mobile you want to set the focus on. All the graphical settings will be applied

relatively to this selected mobile. By default the vessel is selected.

• Number of displayed points

• Link (draw a line between all the points of the mobile)

• Label (add the name of the mobile in the map) close to the last position received

The grid can be either in geographical coordinates (latitude, longitude) or in metric

ones. To switch between the units, press the shortcut keys: [Alt ]+ mouse Left Click. The

metric display has its origin in the upper left corner of the graph.

You can zoom in the graph with a left click and zoom out with a right click.

You can move the center of the graph by holding down [shift] key + left click.

You can erase all points of the selected mobile with the Trace Erase button.

A bigger spot than all the others symbolizes the last position of the displayed point. It

represents the last known position of the mobile. The arrow, which represents the ship, is

oriented following the current ship heading (see Figure 44).

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III.4.3 VISUALIZING WITH THE RELATIVE VIEW

GAPS – User Guide

Window

Access

Window

Description

In the relative view, you can see the trajectory of the mobile relative to the ship. The view

is centered on the vessel. To display the real time data in a relative display, select

Relative tab under Views menu.

The corresponding window appears. The Figure 45 displays the relative view with a GAPS

d at 6 m from the stern and at 2 m from the port side (inside the ship): Xp = -6 m

locate

and Yp = -2 m in this case.

Figure 45 - Relative view

All the graphical settings are the same than in the absolute view except that you have:

• A transparent mode that allows you to see data taken under or behind the ship (case

of a diver swimming under the ship).

• A vector that can be drawn (it draws a line between the last point and the vessel).

You can also choose to see only the Side View or the Top View by clicking the check

boxes on top of both views.

With the Auto Scale option checked, the full extent is made on the data, the ship

disappears, the origin or GAPS remains on the display.

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III.4.4 VISUALIZING WITH THE DEPTH VIEW

GAPS – User Guide

Access

Window

The depth window displays the mobile depth.

To display the real time data in a depth view, select Depth tab under Views menu.

The corresponding window (see Figure 46) appears.

Figure 46 - D

epth view

The graphical settings are the same than in the absolute view.

• Auto Scale: on the immersion, maximum extent of all points

• Auto Frame: on the immersion, maximum extent of the points of the selected

mobile(s)

• Nb Points: as long as the entered number of displayed points is not reached, the

display is compressed. When this maximum number is reached, the display shifts

along the left of the time scale

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III.4.5 CONTROLLING THE GAPS STATUS

The System and Sensors boxes are designed to help you to monitor the GAPS status.

GAPS – User Guide

System Box

The System box is composed of (see Figure 47):

•

A communication button. Changing a functional parameter anywhere in the software

while a GAPS is tracking and validating it will make this button flash with a red frame.

This means that the changed parameter is not applied to the GAPS and that if you

want to apply it you will need to stop the system

This button is labeled as follows:

 “Communication Test” if GAPS is not connected,

 “STOP Tracking” if GAPS is connected and active. Clicking this button stops

the acoustic part of GAPS, no emission and reception is performed anymore.

Inertial and GPS activities (attitude and GAPS/vessel position) are still ON.

 “START tracking” when GAPS is connected but not active.

• A system status light:

 Red when GAPS not connected to the PC (or when it is stopping or starting

the tracking)

 Blue if GAPS is not active

 Green when GAPS connected and active

• Two status and command buttons for Position and Acoustic ping outputs. These

Sensors box

status buttons flash in blue/mauve each time an acoustic ping is transmitted or

position signal is received. This effect gives an idea of the actual recurrences of the

position and acoustic ping transmitted. Clicking on the associated buttons brings you

to the Supervision window with a specific tool box allowing the set-up of acoustic and

position parameters.

Figure 47 - System box

Four status and buttons are available (see Figure 48). Each of these buttons opens

cific tool box. The color button follows a code giving the status of the sensor.

spe

The color code for the four status lights is the following:

• Red for Alarm

• Orange for Warning

• Green for Normal

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GAPS – User Guide

Figure 48 - Sensors Box

In the associated tool box, you can see the operating state of the device:

• Inertial Sensor Status Tool Box: it contains status lights and a diagnostic zone

displaying alarm or warning messages (see Part V).

• Processor Status Tool Box: it contains a diagnostic zone displaying alarm or warning

messages (see Part V).

• Acoustic Array Status Tool Box: it shows the status of the four hydrophones (see

Figure 49). A red status means that the hydrop

hone did not receive an expected

signal. If one of the hydro status stays red during several interrogations the

hydrophone might be damaged (contact iXBlue for support and assistance). The CPU

temperature is the temperature of the electronics contained in GAPS. It is the

temperature of the warmer electronic component (CPU).

• If the rectangle light is orange: the temperature is high (> 70°C). This situation must

be kept under very close control. For example check if the GAPS antenna is not out of

water.

• If the rectangle is red: the temperature is very high (> 75°C). You must switch off the

GAPS and contact iXBlue support.

Figure 49 - Acoustic Array Tool Box

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GAPS – User Guide

• External Sensor Status Tool Box : it allows a quick check on the status of GPS and

optional pressure sensor (see Figure 50). It also contains a diagnostic zone displaying

alarm o

r warning messages.

Figure 50 – Tool box of the External Sensors Status

Ambient

Noise

The sea ambient noise is measured at the hydrophones faces and displayed in the tool

box in the Supervision menu after clicking on the acoustic antenna:

Figure 51 – Tool box displaying the noise level for all the hydrophones

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Page 84

III.5 Recording the Data

A recorder box allows data recording in a file in real time. This recording is automatic

when the check box Automatic Recording is checked (see Figure 52). This check button

e found in the Supervision menu in the toolbox of the MMI parameters button.

can b

The automatic file name format of the file is “YearMonthHourMinuteSecond.dat”.

Each time the data file size reaches 1 Mo a new data file is created.

The whole software configuration is always saved in the first data file.

GAPS – User Guide

Figure 52 - Recorder box – Automatic recording check box

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Page 85

IV OPERATING GAPS

Before starting any operation, you should know what to expect in terms of performances,

GAPS – User Guide

range and accuracy (see section IV.1). Every operation starts by the co

system and its initialization (see section IV.2). During the survey, you ca

operation (see section IV.3).

IV.1 Performances

In complex marine environments, GAPS offers different levels of performances. See

below the global GAPS performances depending on the GPS operating modes (section

IV.2.1) and the variation graphs of the range and the a

and SNR.

IV.1.1 POSITION ACCURACY FOR MT8, MT9 AND ET8 TRANSPONDERS

Characteristics Typical Values

Positioning accuracy

for MT8, MT9, ET8

transponder

• Accuracy: from 0.2 to 0.7%

depending on noise level

• Range: 4,000 m

Deep water Shallow water

ccuracy versus depth, noise level

• Accuracy: around 1%

• Range: > 1,000 m (2 to 4 times

more depending on the weather)

nfiguration of the

n control the

Positioning accuracy

for ORE transponder

GPS Position

accuracy

Position drift

(during GPS drop out)

• Rejected Erroneous Positions:

from 0 to 0.3%

Deep water Shallow water

• Accuracy: around 3 %

depending on noise level

• Range: 1,000 m

Rejected Erroneous Positions:

around 50 % vertically and

propellers stopped

2 to 5 cm (external RTK receiver)

0.5 to 3 m (integrated DGPS or internal or external)

5 to 15 m (GPS receiver)

2 m / 2 minutes

• Rejected Erroneous Positions:

from 0 to 0.3%

• Accuracy: around 2 to 5 %

depending on angle

• Range: a few hundred meters

Rejected Erroneous Positions: from

30 to 90 % depending of the angle

from 0° to 60° from vertical

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IV.1.2 MULTI PATH

The multi-path phenomenon is usually a major issue for standard USBL systems. GAPS

uses wide-band spectrum signals and is fitted with a powerful signal processing that

reduces a lot the result of the multi-path signals.

Nevertheless this phenomenon may happen from time to time and lead to noisy positions

under specific conditions (specific distances between the transponder and/or the GAPS

antenna and a reflective surface).

• Multi-path

GAPS – User Guide

Figure 53 – Multi-path Phenomenon

The transponder transmits one signal. The GAPS antenna receives this signal plus

additional echoes mixed together.

• Analogy with images

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GAPS – User Guide

IV.1.3 R

ANGE VERSUS NOISE LEVEL

The GAPS performances are on the Figure 54 with

• GAPS Signal Level of 191 dB

• Transponder Signal Level = 188 dB

Figure 54 – GAPS Performances in Range versus Noise Level

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Page 88

IV.1.4 ACCURACY VERSUS SNR

The GAPS performances are described on the Figure 55 with:

• Slant Distance ≥ 1,000 m

• Vertical Angle < 30 deg

• Roll & Pitch Error = 0.01 deg

• Heading Error = 0.1 deg

• GPS error ≤ 1.5 m

GAPS – User Guide

Figure 55 – GAPS Performances in Accuracy versus SNR (SNR at GAPS processing output)

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Page 89

IV.2 Initializing and Configuring a Survey

You need to choose the mode in which GAPS is going to operate (section IV.2.1) before

initializing the system (section IV.2.2). The choice of the operating mode constrains the

uration (section IV.2.3).

config

IV.2.1 OPERATING MODES

IV.2.1.1 Synchronization Mode / Recurrence

The system can be synchronized by and with another system or can generate itself its

acoustic recurrences:

• Internal recurrence: the interrogation time for the transponder is automatically

determined by GAPS. The Internal recurrence is fixed: it is configured to a fixed value

with the MMI.

GAPS – User Guide

• External Synchronization: an external system generates a synchronization to

operate GAPS.

• External Synchronization with inhibition: the GAPS minimum recurrence inhibits

the short external recurrence after one received trigger. GAPS is triggered on the

rising edge of the signal. This mode is described on the Figure 56.

Figure 56 – Inhibi

tion window during an external synchronization

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IV.2.1.2 Two Modes

The GAPS interrogates acoustically (transponder mode) or electrically (responder mode).

• Transponder mode: GAPS acoustically interrogates the transponder that replies with

a MFSK signal. The time between signal interrogation and reception is approximately

1 second every 750 m transponder range with a velocity of 1500 m/s.

• Responder mode: the transponder is electrically triggered through the SYNCHRO

OUT- RESPONDER MODE output and GAPS does not send acoustic signal anymore.

This mode has many advantages:

GAPS – User Guide

 The position update is twice faster in responder mode than in transponder

mode because there is only one acoustic travel in this mode. The first travel is

electric. There are two acoustic travels in transponder mode.

 The transponder cannot be accidentally triggered by any parasitic sound.

 The transponder is always triggered despite noise (e.g. ROV propellers).

 Depending on the environmental conditions, the maximum range of the system

is sometimes limited by the reception of the acoustic triggering signal by the

transponder. This is no more limitation in responder mode and the maximum

range is only limited by the reception of the reply by the GAPS acoustic array.

The drawback is that the electrical signal has to be transmitted up to the transponder

usually through an electrical or a fiber optic wire or by using synchronous clocks (GAPS in

external synchronization mode).

IV.2.1.3 Multi Transponders Mode

Several Acoustic Transponders can be interrogated simultaneously. The transponders are

separated thanks to the two MFSK codes (22, 23) and the four Individual Interrogation

Frequencies (IIF). Thus, up to 8 (4 x 2) transponders can be positioned.

You can also use seven beacons in transponder mode (by using the four different

Individual Frequencies available and the two codes 22 and 23) and one beacon in

responder mode in the same configuration.

If you want to use two transponders, the first one in transponder mode, the second one in

responder mode, and if you want to interrogate them simultaneously (i.e., in the same

recurrence), both transponders must be configured with the same IIF. When they are

configured with two different IIF, they will be interrogated alternatively every second

recurrence. See Figure 57.

Figure 57 -

Two Transponders in Transponder and Responder modes

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GAPS – User Guide

When a transponder is configured in transponder mode, no signal is generated on the

SYNC OUT output of the ECB (responder mode).

HEN THE TWO INTERROGATION FREQUENCIES ARE DIFFERENT, THE BLANKING TIME IS HIGHER

THAN THE ACOUSTIC RECURRENCE. IN A SINGLE TRANSPONDER MODE, YOU CANNOT HAVE A

IV.2.2 I

Procedure

BLANKING TIME HIGHER THAN THE ACOUSTIC RECURRENCE

BLANKING TIME HIGHER THAN THE RECURRENCE

TWO DIFFERENT FREQUENCIES

TRANSPONDER HARDWARE AND LET A BLANKING TIME LOWER THAN THE RECURRENCE IN THE

MMI. O

NITIALIZING

WAIT AT LEAST 20 S BEFORE TURNING IT ON AGAIN

DO NOT

NLY THE BLANKING TIME SET IN THE HARDWARE IS TAKEN INTO ACCOUNT

GAPS

F YOU TURN OFF

TRANSMIT ACOUSTICALLY WITH

Step Action

Turn the ECB switch to ON.

On the ECB, turn GAPS switch to ON.

GAPS

BY PRESSING THE

. I

N THE

MMI

YOU CANNOT SET UP A

. S

O WHEN YOU USE TWO TRANSPONDERS WITH

MAKE SURE TO HAVE THE CORRECT SETTINGS IN THE

GAPS

POWER SWITCH ON THE

ECB,

MAKE SURE TO

GAPS

IN THE AIR

GAPS is running its initialization tests. Wait for about 30 s.

Launch the MMI software on your PC.

MMI scans all the ports of the PC. After completing this communication test successfully,

the command button on the upper right corner of the MMI window becomes a “Start

tracking” button.

Press START tracking button in the MMI.

This action starts the acoustic cycle of GAPS. The INS needs 5 minutes before being

operational.

Check for end of the alignment inertial sensor alarm message on the MMI software: in

the sensor box, check the Inertial Sensor status light: orange during the “coarse

alignment”, green during the “fine alignment” (typically 30 minutes but could be longer).

Check for available Data control views in MMI (absolute, relative, depth).

End of procedure.

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INS

Initialization

GAPS – User Guide

• During the first five minutes after powering-on, the inertial system performs its coarse

alignment:

 Inertial sensor data (accelerometers and gyrometers) are computed to

estimate heading, roll and pitch angles.

 At sea, it is recommended that the system is kept as steady as possible during

coarse alignment: oscillations around a mean position or smooth drift are

permitted but accelerations should be avoided. Leaving the vessel adrift for 5

minutes would lead to satisfactory conditions for coarse alignment.

 No estimation of position or speed, nor errors, are done by the INS during the

coarse alignment: the data provided by external sensors (lever arm

compensated) are used directly.

• After the coarse alignment phase, the GAPS is ready for navigation. Kalman filter is

activated to compute and estimate position and speed with an optimal accuracy. The

INS switches to the “fine alignment” phase to improve the accuracy of roll, pitch and

heading estimations.

 During the fine alignment phase, movements of the vessel are required. 90

degrees rotations are even recommended so that the Kalman filter assesses

the sensors bias on different axes.

 Error estimations from the INS Kalman filter are improved when optimal

trajectories are performed. The optimal trajectory to achieve fast fine alignment

is “staircase” shaped, as illustrated in Figure 58, with a typical duration of 3 to

5 minutes fo

r each step. Such a trajectory allows the Kalman filter to assess all

sources of errors of the system, to correct them and to achieve optimal

performances at the end of the fine alignment process.

 When a “staircase” shaped trajectory is performed, the fine alignment phase

would typically last for less than 20 min.

 The fine alignment requires the GPS to provide valid data to the system. the

INS uses both inertial sensors and external sensors to compute optimal

estimates of position, speed, attitude and heading.

 The fine alignment is ended automatically when the heading covariance is

below 0.1 degree.

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GAPS – User Guide

Starting point

Arrival point

Figure 58 - Illustration of optimal trajectory for fine alignment

The inertial sensor status light turns green at the end of the coarse alignment. You can

then start to operate with GAPS. The accuracy of the INS is optimal at the end of the fine

alignment. At the end of the fine alignment, the message “fine alignment” disappears from

the inertial sensor tool box.

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GAPS – User Guide

IV.2.3 C

Configuring MMI general parameters on a User PC

GPS Lever

ONFIGURING THE MISSION PARAMETERS

For more details on these procedures, please refer to section III.3.

Step Action

Under the Mission menu, select the Vessel tab, enter the ship dimensions.

Under the Mission menu, select the S/Velocity tab, enter the velocity profile.

Under the Mission menu, select the Supervision tab, enter the interface parameters:

• In the Serial Link tool box, choose GAPS Regular for the Position protocol and

set-up the serial parameters

• In the Output toolbox, choose the output position protocol if needed

End of procedure.

In the MMI software, the GPS lever arms, if they exist, have to be entered.

Arms

About the GPS antenna, two main configuration cases exist:

• The GPS antenna is vertically above GAPS

• The GPS antenna is NOT above GAPS

Configuring the GPS lever arms when the GPS is vertically above GAPS

Step Action

Under the Mission menu, select the Vessel tab, set the GPS X, Y lever arms to zero.

Enter the Z lever arm.

• If GAPS is mounted on a pole, GAPS should be placed in a way that the

hydrophone H1 is oriented towards the bow of the ship.

• If a rigid rope holds GAPS, you always have a slight error induced by the motion

of the rope, even if the GPS antenna is put vertically above GAPS.

End of procedure.

Configuring the GPS lever arms when the GPS is NOT vertically above GAPS

Step Action

Under the Mission menu, with the Vessel tab selected, set the position offsets X, Y, Z of

the GPS antenna with respect to GAPS.

End of procedure.

GPS lever arms must be entered in the GAPS reference frame.

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GAPS – User Guide

IV.2.4 I

Procedure

NSTALLING THE TRANSPONDERS

Step Action

In the MMI software, under the Transponders menu, add the transponder to your

system and set up its configuration (see Part III.3.10 of this manual).

In the associated toolbox, check In Use box to make it operational and set the

associated parameters up (at least IIF, MFSK code, transponder/responder mode, turn

around time, filter).

In case of a transponder with a remote transducer, connect the remote transducer to the

transponder body.

Plug the transponder for power supply to the vehicle carrying it.

This connection is used in both transponder (only power supply) and responder mode

(power supply and triggering coming from GAPS).

In responder mode, connect the vehicle to the “Synchro Out” BNC plug on the ECB or to

your SOURIAU socket if you do use the ECB. For transponders triggered by a TTL

signal, plug the responder cable on the rear face of the ECB. For the transponders

triggered by a differential signal, plug the responder cable on the front face of the ECB.

End of procedure.

MPORTANT FOR

O NOT FORGET TO SELECT

THE RECEPTION CHANNEL FREQUENCY YOU WANT TO USE BY SELECTING IT WITH THE SWITCH

LOCATED ON THE BOTTOM END PLATE OF THE TRANSPONDER

THE CODE, TURN AROUND TIME AND BLANKING TIME BY THE MEAN OF SWITCHES LOCATED

INSIDE THE TRANSPONDER

CTUAL TRANSPONDER SETTINGS HAVE TO MATCH THOSE INTRODUCED INTO THE

MT8

AND

ET8 T

RANSPONDERS

GAPS MMI

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Page 96

IV.3 Monitoring the Survey

IV.3.1 VISUALIZING THE TRAJECTORY

Refer to section III.4 for a complete description of the control windows in the MMI

software.

IV.3.2 LIST OF THE SYSTEM STATUS

GAPS – User Guide

System Box

Sensor Box

Button/ status light Meaning

GAPS is not connected

GAPS is connected and active. GAPS is pinging.

GAPS is connected, not acoustically active (but it

gives the ship position).

Position and Acoustic lights Meaning

Flashing in blue/mauve each time a position is

computed and an acoustic ping is sent.

Status light Meaning

Red light in case of an alarm

Menu Text

Label

When you modify some parameters in the different windows or tool boxes, the

corresponding menu titles are set to red. This color code means that modifications have

been made but not applied yet in the MMI and/or GAPS itself.

Green light for a normal status

Orange light in case of a warning

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Page 97

IV.3.3 LIST OF THE WARNING MESSAGES AND TROUBLESHOOTING

These messages appear in the tool boxes relative to the processor, the inertial sensor, the

acoustic array and the external sensor. For example:

GAPS – User Guide

Figure 59 - Diagnostic dialog box in the acoustic array toolbox

Processor

Warning Messages Meaning Possible Cause(s) Checks, possible solutions

Negative Stack Time

or Stack Error

Mirror Solution Solved ambiguity of two

Filter Attenuation Position smoothed by the

Timing error in the attitude

data array

symmetrical positioning

solutions

filter so it is accepted

CPU overload Reduce the recurrence

A hydrophone has not delivered

useful information (too much

noise, out of service …), the

three others worked properly.

Two positioning solutions are

found with three hydrophones.

The system has been able to

solve the ambiguity.

Very noisy raw data that trigger a

smoothing and predicting filter (if

you have activated this option).

Check the SNR in the MMI.

Check that it is not permanent and that

it does not concern always the same

hydrophone in the Acoustic Array

Status.

Reduce the general ambient noise. You

can for example reduce the speed or

the variable pitch of the propellers.

If it happens too often, check the

acoustic noise of the ship (see

convergence error below).

Inertial System

Warning Messages Meaning

Alignment Initialization of the inertial sensor (coarse alignment), it takes 5 minutes after powering of GAPS

and before being operational. It is better to let the ship drift during these 5 minutes.

Fine Alignment End of the initialization of the inertial sensor. It can take 30 minutes before being fully

operational. Caution: on a ship that is alongside the wharf, this final initialization can last

permanently.

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GAPS – User Guide

Acoustic Array There are no warning messages available.

External Sensors

Warning Messages Meaning

Pressure Not Used Pressure sensor data inconsistent with valid position computation. The pressure sensor data is

rejected.

GPS Data Invalid GPS data is not valid.

GPS Data Noisy GPS data is noisy.

GPS Data Rejected GPS data is rejected.

IV.3.4 ERROR MESSAGES

These messages appear in the tool boxes relative to the processor, the inertial sensor, the

acoustic array and the external sensor.

Processor

Error Messages Meaning Possible Cause(s) (not

exhaustive)

No Detection. None of the four hydrophones

is receiving any signal

Negative Travel Time Negative time found in travel

time computation

Convergence Error No convergence found in

position computation

If the message appears alone,

the transponder could not

transmit.

The transponder might be too

close to the GAPS antenna in

responder mode.

Anomaly in the detection process

of GAPS.

Turn around time of the

transponder different from the

value in the GAPS MMI and

transponder too close to the

GAPS antenna.

Noisy raw data Check the noise recorded by the

Checks, possible solutions

Check if the transponder transmits

(for example try to hear the ping).

Move the transponder away from

GAPS.

Turn off GAPS and after at least 20

seconds turn it on again.

Check if the values of the turn around

time in the MMI and in the

transponder are identical.

Check the external synchro.

Check for unexpected triggering of

the transponder due to heavy

acoustic noise for example.

antenna and try to reduce it (for

example slowing down the propeller

line shaft)

Velocity profile Error Error during application of

sound velocity profile

Not corrected sector

jump

Corrected sector jump Position found in a wrong

Position found in a wrong

angular sector below GAPS,

NOT corrected.

angular sector below GAPS,

position is now corrected.

The depth of the last layer of the

velocity profile is higher than the

computed depth of the

transponder.

Acoustic noise conditions

specially rough.

Acoustic noise conditions

specially rough.

MU-GAPS-AN-003 Ed. L – May 2012

Introduce an additional layer with a

greater depth than the actual depth of

the transponder.

Same as Convergence Error (if the

problem occurs in a repetitive way)

Same as Convergence Error (if the

problem occurs in a repetitive way)

Page 99

GAPS – User Guide

Error Messages Meaning Possible Cause(s) (not

exhaustive)

Mirror Ambiguity The system has entered in a

process to solve the ambiguity

between two possible solutions.

The process has not

succeeded.

Above Surface The computed position is

above the water surface. The

position is rejected.

Rejection Filter This alarm occurs when we

know that the computed

position is not valid. In this case

we do not feed the filter with

this position.

A hydrophone has not delivered

useful information (too much

noise, out of service …), the

three others worked properly.

Two positioning solutions are

found with three hydrophones.

The system has NOT been able

to solve the ambiguity.

Most probably the velocity profile

is erroneous because the

computed position is inconsistent

(in the air).

Inconsistent value compared to

the previous positions has been

rightfully rejected.

Checks, possible solutions

Check the SNR value in the MMI.

Reduce the general ambient noise.

You can for example reduce the

speed or the variable pitch of the

propellers.

Same as in Mirror Solution.

Check the velocity profile.

Perform again the acquisition of a

velocity profile.

If this stays an isolated event, there is

nothing to do.

In the opposite case, consider the

presence of reflections and multiple

travels of the acoustic wave. Increase

the recurrence value.

Reduce the general ambient noise as

in the convergence error and mirror

ambiguity.

Delta T Filter Error The date of emission of the

beacon is older than the date of

the position output by the filter.

The internal data flow is late due

to CPU overload.

Lower the Output rate of the user

protocol.

Contact iXBlue support

Inertial Sensor

Error Messages Meaning Possible Cause(s)

(not exhaustive)

ADC1 Saturation Overload on the ADC1 of the INS Contact iXBlue customer support

ADC2 Saturation Overload on the ADC2 of the INS Contact iXBlue customer support.

ADC3 Saturation Overload on the ADC3 of the INS Contact iXBlue customer support.

Accelerometer X1 Error Error on the accelerometer X1 of the INS Contact iXBlue customer support.

Accelerometer X2 Error Error on the accelerometer X2 of the INS Contact iXBlue customer support.

Accelerometer X3 Error Error on the accelerometer X3 of the INS Contact iXBlue customer support.

Heading Not Valid Heading data of the INS is not valid Message appears often

after an ADC Overload

or accelerometer error.

Attitude Not Valid Attitude data of the INS is not valid Message appears often

after a ADC Overload

or accelerometer error.

Checks, possible solutions

Wait a few minutes and all should

come back in order.

If not contact iXBlue customer

support.

Wait a few minutes and all should

come back in order.

If not contact iXBlue support.

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Acoustic Array

External Sensor

GAPS – User Guide

There are no error messages available.

Error Messages Meaning Possible Cause(s) (not

exhaustive)

GPS Not Received GPS data expected was not received

in input.

Pressure Not Received Pressure data expected was not

received in input.

GPS not properly connected,

defectuous cables (the Y

cable or the 10 m GPS

cable).

Unavailable satellites

Pressure sensor defectuous,

not properly connected, not

at the right format or serial

port not properly

configurated.

Checks, possible solutions

Check the cables and connections.

Check that the satellites are

available.

Check the input data of the ECB

($PMEVL, NMEA format), serial port

configuration …

MU-GAPS-AN-003 Ed. L – May 2012