northern watch underwater sensor system design...

Northern Watch Underwater Sensor System Design Concept

Garry J. Heard Nicos Pelavas

Defence R&D Canada Atlantic

Technical Memorandum

DRDC Atlantic TM 2010-248

November 2010

A supporting document for the Northern Watch Technology Demonstration Project describing the

design of the Underwater Sensor System and the development of hardware required to meet the

goals of the project.

Her Majesty the Queen in Right of Canada, as represented by the Minister of National Defence, 2010

Sa Majest la Reine (en droit du Canada), telle que reprsente par le ministre de la Dfense nationale,

2010

DRDC Atlantic TM 2010-248 i

Abstract ..

In this document we provide a detailed description of the design of the Underwater Sensor

System (UWSS) that will be used in the Northern Watch (NW) Technology Demonstration

Project (TDP). The test and build cycle of the acoustic arrays is discussed with special attention

given to a thorough testing of the prototype array components and to the prototype array itself. A

modular array design is presented allowing for the independent testing of hydrophones and

cables, thus enabling on-site maintenance of the array and maximizing survivability. A

description of the specific array design is given including array extenders and repeaters along

with suggested modifications as a result of previous years deployments. The components

constituting the dry-end are listed and explained. We introduce the new Remote Control Interface

hardware required to meet the goals of the NW TDP, its primary function will be to control the

various array system components through a communications link with the System Integration

Device. As part of preparing for a continuous year-long operation the required redundancy of

system components and number of spares is quantified. Other areas requiring further investigation

are indicated.

Rsum .....

Dans le prsent document, nous dcrivons de faon dtaille la conception du systme de capteurs

sous-marins (SCSM) qui sera utilis dans le cadre du projet de dmonstration de technologie

(PDT) de surveillance du Nord. Le cycle dessai et de construction de rseaux acoustiques est

examin, et porte en particulier sur une mise lessai complte du rseau prototype et de ses

lments. Un modle de rseau modulaire est en outre prsent pour permettre la mise lessai

indpendante des hydrophones et des cbles, et ainsi faciliter lentretien sur place du rseau et

optimiser sa surviabilit. Le document dcrit galement le modle de rseau, y compris les

extenseurs et les rpteurs, ainsi que les modifications suggres la suite de dploiements

antrieurs. Les lments qui composent lextrmit sche sont rpertoris et dcrits. Par ailleurs,

nous prsentons le nouveau matriel de linterface de tlcommande ncessaire latteinte des

objectifs du PDT de surveillance du Nord. Cette interface servira surtout contrler les divers

lments du systme rseau au moyen dune liaison de communication avec le dispositif

dintgration des systmes. Dans le cadre de la prparation au fonctionnement continu pendant

un an, nous quantifions la redondance ncessaire des lments du systme et du nombre de pices

de rechange. Nous prcisons enfin dautres questions examiner de faon approfondie.

ii DRDC Atlantic TM 2010-248

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DRDC Atlantic TM 2010-248 iii

Executive summary


Garry J. Heard; Nicos Pelavas; DRDC Atlantic TM 2010-248; Defence R&D Canada Atlantic; November 2010.

Background: The Northern Watch (NW) Technology Demonstration Project (TDP) is a

multi-year project involving a number of DRDC centers. Its goal is to develop the capability to

remotely monitor Barrow Strait near Devon Island for a period of 12 months and to relay this

information in near real-time to a southern analysis station for further processing. The project

challenges are the development of remote control capabilities, integration of terrestrial and

underwater sensor systems, power production and management, communications, and

engineering of robust systems to sustain the extended period of unmanned operation in Arctic

conditions.

Results: In this document we establish a procedure for building and testing underwater acoustic

arrays such that weaknesses are eliminated early in the development phase. A rugged array design

is presented that utilizes the experiences gained from previous array constructions and takes into

consideration the research invested in the development of the newly constructed acoustic array for

the Norwegian defence laboratory, FFI. New hardware components are introduced that facilitate

the remote control capabilities necessary for the underwater sensor system. Enhancements have

been included to ensure reliability such as the presence of redundant systems, isolation of data

pairs in order to maintain data stream integrity, among others.

Significance: Adherence to the timeline and guidance in this document will ensure that a robust

remotely operated underwater sensor system is developed. An array construction that separates

the array cable and hydrophone nodes is presented. This allows for independent testing of

components and rapid isolation of problems. In addition, on-site maintenance of array

components can now be implemented. Although these arrays are more expensive than earlier

resin based arrays they are far more rugged, and still less expensive than traditional array

constructions.

Future plans: Initiate prototype component builds and tests in accordance with this document.

In cooperation with contractors, we will develop the specifications for the internal hardware

requirements of the Remote Control Interface and identifying modifications required to pre-

existing underwater sensor system components. Related to this development is the requirement

for NW members to establish a unified message format for the communication of their associated

Remote Control Interface with the System Integration Device.

iv DRDC Atlantic TM 2010-248

Sommaire ..


Garry J. Heard; Nicos Pelavas; DRDC Atlantic TM 2010-248, R & D pour la dfense Canada Atlantique, novembre 2010.

Introduction ou contexte : Le projet de dmonstration de technologie (PDT) de surveillance du

Nord est un projet pluriannuel auquel participent divers centres de RDDC. Il vise dvelopper

une capacit de surveillance distance du dtroit de Barrow, prs de lle Devon, pendant

douze mois et de transmission des renseignements en temps quasi rel une station danalyse,

situe plus au sud, aux fins de traitement subsquent. Les dfis relever dans le cadre du projet

sont le dveloppement de capacits de tlcommande, lintgration de systmes de capteurs

terrestres et sous-marins, la production et la gestion de lnergie, les communications, ainsi que la

conception de systmes robustes pour soutenir la priode prolonge de fonctionnement autonome

dans des conditions arctiques.

Rsultats : Dans le prsent document, nous tablissons une procdure de fabrication et de mise

lessai de rseaux acoustiques sous-marins afin de permettre de corriger les lacunes au dbut de la

phase de dveloppement. Nous prsentons aussi un modle de capteur robuste qui repose sur les

connaissances tires des constructions antrieures de rseaux et tient compte des recherches

ralises dans le dveloppement du nouveau rseau acoustique construit pour le laboratoire

norvgien de la dfense, FFI. De plus, de nouveaux lments matriels introduits facilitent les

capacits de tlcommande ncessaires pour le systme de dtection sous-marine. Des

amliorations sont en outre incluses aux fins de fiabilit, dont la prsence de systmes redondants

et lisolation des paires de donnes afin de maintenir lintgrit des trains de donnes.

Porte : Le respect des dlais et des directives dans le prsent document permettra le

dveloppement dun systme de capteurs sous-marins tlcommand et robuste. Nous prsentons

une construction de rseaux dans laquelle les cbles de rseaux et les nuds des hydrophones

sont spars. Ce type de construction permet la mise lessai indpendante des lments et le

reprage rapide des problmes. Par ailleurs, lentretien sur place des lments du rseau peut

maintenant tre mis en place. Bien que ces rseaux soient plus dispendieux que les anciens

rseaux polymres, ils sont beaucoup plus robustes et demeurent moins coteux que les

constructions traditionnelles de rseaux.

Recherches futures : Nous devons entreprendre la construction et la mise lessai des lments

prototype conformment au prsent document. En collaboration avec des entrepreneurs, nous

dvelopperons des spcifications pour les exigences du matriel lintrieur de linterface de

tlcommande et dterminerons les modifications apporter aux lments actuels du systme de

capteurs sous-marins. Dans le cadre de ce projet de dveloppement, les membres du projet de

surveillance du Nord doivent en outre tablir un format de message unique pour les

communications entre leur interface de tlcommande connexe et le dispositif dintgration des

systmes.

DRDC Atlantic TM 2010-248 v

Table of contents

Abstract .. ................................................................................................................................. i

Rsum ..... ................................................................................................................................... i

Executive summary ........................................................................................................................ iii

Sommaire .. ..................................................................................................................................... iv

Table of contents ............................................................................................................................. v

List of figures and table ................................................................................................................. vii

1 Introduction ............................................................................................................................... 1

1.1 Objectives ...................................................................................................................... 1

1.2 History ........................................................................................................................... 1

1.3 No Fail Approach .......................................................................................................... 2

1.4 Contracting Plan ............................................................................................................ 3

2 Overview ................................................................................................................................... 4

2.1 Deployment Location and Plan ..................................................................................... 4

2.2 UWSS Schedule ............................................................................................................ 6

2.3 Independent Array Developments ................................................................................. 7

3 System Design .......................................................................................................................... 9

3.1 Array Design ............................................................................................................... 10

3.2 Cables .......................................................................................................................... 13

3.3 Repeaters ..................................................................................................................... 13

3.4 Dry-End ....................................................................................................................... 14

3.4.1 Overview ....................................................................................................... 14

3.4.2 Remote Control Interface .............................................................................. 15

3.4.3 Power ............................................................................................................ 16

3.4.4 Array Receiver .............................................................................................. 17

3.4.5 Data Store ...................................................................................................... 17

3.4.6 Server / Data Processor ................................................................................. 17

3.4.7 Southern Analysis Station ............................................................................. 18

4 Array Development Plan ........................................................................................................ 19

4.1 Transducer Prototypes ................................................................................................. 20

4.1.1 Norwegian Array Development .................................................................... 20

4.1.2 Test Plan ........................................................................................................ 21

4.1.3 Exit Point ....................................................................................................... 21

4.2 Array 1 ......................................................................................................................... 22

4.2.1 Exit point ....................................................................................................... 22

4.3 Array 2 & 3 .................................................................................................................. 22

4.4 Spares .......................................................................................................................... 23

vi DRDC Atlantic TM 2010-248

4.5 Component Re-use ...................................................................................................... 23

4.6 Other Components ....................................................................................................... 24

5 Conclusion .............................................................................................................................. 25

References ..... ............................................................................................................................... 26

List of symbols/abbreviations/acronyms/initialisms ..................................................................... 27

DRDC Atlantic TM 2010-248 vii

List of figures and table

Figure 1 The geographic location of the demonstration site. The arrays are deployed on the

north side of Barrow Strait near Gascoyne Inlet on Devon Island. ............................... 5

Figure 2 A view of the Gascoyne Inlet field camp on Devon Island, August 2009. ...................... 5

Figure 3 Illustration of the two telemetry cables and the deployment of the arrays located

between anchor points. .................................................................................................. 6

Figure 4 Approximate timeline for the UWSS build and test plan. ................................................ 7

Figure 5 Project Cornerstone RDS-based arrays in the back row with the processor units in

front. .............................................................................................................................. 8

Figure 6 Norwegian array initial design concept illustrating array cable breakout with

hydrophone connected. Courtesy of Omnitech Electronics Inc., Dartmouth, NS,

CANADA. ..................................................................................................................... 9

Figure 7 Overview of the system design. ..................................................................................... 10

Figure 8 Repeater cages ready for deployment. Completed units are on the order of 2-m

long. ............................................................................................................................. 14

Figure 9 The UWSS Dry-End configuration showing the Remote Control Interface

connectivity. ................................................................................................................ 16

Table 1 Hydrophones occurring in Low Frequency (LF), Medium Frequency (MF), and High

Frequency (HF) sub-arrays along with their displacements relative to the first

hydrophone (H0). ........................................................................................................ 12

viii DRDC Atlantic TM 2010-248

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DRDC Atlantic TM 2010-248 1

1 Introduction

1.1 Objectives

The objective of this document is to provide an overall description of the underwater sensor

system (UWSS) design that is to be used in the Northern Watch (NW) Technology

Demonstration Project (TDP). This document will provide guidance in the generation of contract

documents that will provide the electronic expertise and construction effort that will produce the

UWSS. Another purpose of this document is to provide information to senior management

concerning the UWSS and our plans for its testing and deployment so that project approvals may

be based on actual knowledge of the sensors.

In the earlier stages of the NW TDP, documentation was necessary in order to evaluate and

endorse a proposed sensor system. At that time, this document was submitted to the NW

management team for the purpose of evaluating the UWSS. This Technical Memorandum is

intended to be a historical record documenting the early stages of the design of the UWSS.

Inevitably, as development continues the design of the UWSS will change from what is presented

here. We hope that this document will provide some framework and guidance for future

development of semi-autonomous UWSS.

1.2 History

The NW project has had a somewhat difficult history. The project was approved in 2007 and a

very short visit to the project site at Gascoyne Inlet followed soon after the approvals. This short

visit was conducted in extremely benign conditions and this was somewhat unfortunate as it did

not forewarn the participants as to the severity of the weather conditions that are possible.

In the summer of 2008 a full field trial was mounted and we attempted to deploy both the UWSS

and the above surface sensors. Unfortunately none of these sensors were successfully deployed.

The UWSS was hampered by extremely poor weather conditions and a very short duration

provision of ship services. The UWSS telemetry cable was deployed successfully, but there was

never an opportunity to deploy the actual arrays.

Although the telemetry cable was deployed, there were issues with the deployment and

essentially the field trial was a learning experience for both DRDC and the Canadian Coast Guard

(CCG) personnel who were assisting us.

After the CCG left Gascoyne Inlet the weather deteriorated further and things became very

difficult at the camp. No aircraft were able to visit the camp for a total of 11days. The weather

conditions prevented some of the personnel from reaching the camp and some equipment and

food supplies were also stranded. The conditions prevailed to the conclusion of the field trial and

there was little success in the deployment of the sensor systems.

After this field trial the project was stalled by a Red Card condition. No funds were allowed to

be spent and a great deal of project re-planning was carried out. In the end, permissions were

given for the UWSS to be deployed in the summer of 2009.

2 DRDC Atlantic TM 2010-248

After the experiences of the previous year almost every procedure and item was altered. The

deployment procedure, vessels, equipment, the array cables and sensors were all changed. A

major change was to plan for the use of a second telemetry cable and the deployment plan was

changed to allow only one array to be attached to each telemetry cable. The telemetry cables and

repeaters were altered to provide a second communications channel that was capable of either

supporting a second array or handling the data of the first array in the event that some

components in the primary telemetry channel were damaged. This redundancy was to allow for

failures and flexibility in the deployments.

In addition, the CCG vessel was reserved for the maximum allowable time to help offset the

problems that could arise with the weather conditions. This was a very good decision! The

weather was better in 2009, but it was still problematic.

Both UWSS arrays were successfully deployed in 2009, but the first array began to fail shortly

after deployment. This array was subsequently replaced with the spare array, which unfortunately

also began to fail after deployment. After a few days, the second array deployed also began

failing. Both the first and third arrays were recovered, but the second array was left on the sea

floor. The arrays were able to operate in a degraded condition for almost two weeks before we

were forced to turn them off.

Despite the failing arrays we were able to collect a great deal of useful data. The arrays are

capable of providing excellent acoustic and electromagnetic data when they are operating

properly. We were able to measure ambient noise levels, propagation losses, and we were able to

detect and process data from passing vessels.

Louder vessels were detectable on the opposite side of Barrow Strait almost 70 km distant. We

detected a range of vessel types including a small open boat, the CCG Terry Fox, a freighter, and

several passenger vessels.

1.3 No Fail Approach

To the greatest extent possible within the available funding envelope that is anticipated, we are

adopting a no-fail approach. In order to make this approach mean something, it is necessary to

ensure that we will have replacement parts and options in deployment and array configurations.

We will also acquire the best possible equipment for the deployment and items such as acoustic

releases so that we can recover arrays or cables in the event of unexpected deployment

termination or failures of components.

A list of the steps to be followed to ensure successful demonstration follows:

A spare array will be made available to replace an array if one should fail during the ship support period.

Spare cable sections will be available in case of damage during a deployment or recovery operation.

The dry-end components will all be provided with spares that can be remotely switched into operation. (Array Receivers, power supplies, Server/Data Processor, and communications

paths.)


A significant period of ship support time will be sought to allow for prolonged bad weather.

Recovery and deployment gear will be constructed ahead of time and shipped to the site.

A remote operator control system will be developed that will allow the operator to turn arrays on and off, transmit selected data south, re-program both the arrays and server

systems, and to switch dry-end subsystems in and out in the event of failures.

An extensive period of testing both in the shop and in the field will be applied to all components.

Extensive consulting with materials specialists will be used to avoid problems similar to those that plagued the 2009 arrays.

The arrays will be acoustic only. The electromagnetic sensors will be eliminated from the new development. This will make for easier deployments, lower costs, and a more uniform

array structure. The performance of the EM sensors in the deep water does not warrant their

inclusion in this demonstration system. Cost savings from the exclusion of the EM sensors

will assist in funding the more costly structures needed to ensure array integrity.

A phased approach to the construction will be adopted that begins with component prototypes, follows with a full array that is field tested, and ends with a second build and

field test of the final two arrays and the full UWSS.

Time is already of the essence in the development of the UWSS for the NW project. Although we

do not expect to deploy the arrays until the summer of 2012 there is barely enough time to

complete the planned development cycles. This is complicated by cash phasing, fiscal year

limitations, and administrative approvals that could easily result in a year long delay if windows

of opportunity are missed.

1.4 Contracting Plan

The project currently has an active contract with Omnitech Electronics Inc. This contract was

originally developed with an unfunded option for equipment costing as much as $3,000,000 more

than the original deliverable.

The Omnitech contract has been amended several times with resulting increase in the funding

levels and an extension of the contract duration. The remaining unfunded work portion is still

significant and expected to be more than sufficient to cover the costs of the new UWSS

development.

Omnitech is the clear industrial leader in experience with the rapidly deployable systems (RDS)

technology on which the UWSS is based. In addition, Omnitech has licensed the RDS technology

and has already completed an international sale of an array system to L3 Communications.

Omnitech was a contracted partner in the DRDC-led sale of RDS systems to Australia's DSTO

laboratories. Omnitech is now in the process of designing a new advanced RDS-based array

system for Norway's FFI Laboratory. They were contract partners in the development of the

Long-Range Acoustic Bearing (LRAB) homing system for the recent Project Cornerstone field

trial. The LRAB system has already attracted commercial interest and Omnitech is expected to

build copies for sale with new Explorer AUVs.


Due to the existence of an active contract with the most experienced company in the RDS

technology and the already approved option for significant unfunded work, it makes sense to seek

a further amendment to the Omnitech contract to ensure that sufficient funds are available to

support the new UWSS development. A significant increase in the current funding level will be

sought once the amended statement of work has been produced. Due to the long range planning of

the TDP, it will also be necessary to seek a further extension of the contract time-line to support

the UWSS to the completion of the TDP.

Due to a different expertise requirement for the development of the data processing and remote

control station, it is suggested that a new SOR for a separate contract be developed for the

southern analysis station and the codes that must be distributed throughout the UWSS to make

this possible.

2 Overview

This section provides a general overview of the UWSS. It includes details of the deployment, the

schedule, and other related array developments.

2.1 Deployment Location and Plan

There will be two underwater arrays included in the UWSS. These arrays will be deployed in

Barrow Strait (Fig. 1) and will be connected to the shore by telemetry cables that terminate in the

Science Hut at the Gascoyne Inlet Camp (Fig. 2). There will be two telemetry cables, each with

one array attached. Each cable will be capable of supporting two arrays, but this would only

occur if all other possibilities have been exhausted. The telemetry cables will be a nominal 9-km

long. The arrays will therefore be very close to the northern side of Barrow Strait. Figure 3 is an

illustration of the array locations and cable configuration.

The arrays will be deployed at locations close to those used for the arrays during 2009. The array

to the west will be in water depths of approximately 120 m. The array to the east will be in water

depths between 170 and 200 m, depending on the exact location chosen. The inter-array distance

will be approximately 6 km.


Figure 1 The geographic location of the demonstration site. The arrays are deployed

on the north side of Barrow Strait near Gascoyne Inlet on Devon Island.

Figure 2 A view of the Gascoyne Inlet field camp on Devon Island, August 2009.

100 Kilometers 0 50


Figure 3 Illustration of the two telemetry cables and the deployment of

the arrays located between anchor points.

2.2 UWSS Schedule

There is already insufficient time for a sequential approach to the scheduling of the UWSS. Work

must begin as soon as possible and there must be an overlap of some activities. Figure 4 is an

approximate time line for the build and test cycles required. The top row of the diagram shows

the calendar with the fiscal years marked in bold. The middle area with the arrows shows the

milestones of the process and the lower region shows the main tasks and durations in months.

There is a known funding issue with Build Array 1 milestone, which marks the beginning of the

array construction. This 6-month long assembly task begins prior to the end of FY09/10 and there

is insufficient funding available in the current fiscal year to begin this task. If additional funds are

not available, there will be a very significant overlap in the Assembly tasks. To further

complicate matters this time line does not show interactions with other parts of the NW project

that will further stress the financial limits.

2000 Meters 1000 0


Prototype 6 m Testing 4 m

Figure 4 Approximate timeline for the UWSS build and test plan.

2.3 Independent Array Developments

The arrays deployed in 2009 suffered from a materials incompatibility that led to water ingress

into the sensors and the failure of the arrays after a short operating period. A subsequent forensic

investigation into the array failures pointed to the fundamental source of the failures and to a

number of construction process errors and design flaws that contributed.

Since the occurrence of this failure both companies involved have made considerable effort to

produce better hydrophone designs and the employment of more compatible materials. DRDC

staff have consulted on every step of this effort and have provided a contract in support of Project

Cornerstone that has led to the development of a 5000-m capable digital RDS hydrophone array.

The Project Cornerstone array involved a significant amount of pressure testing on hydrophone

prototypes. This work was successfully completed with the production of three 7-hydrophone

arrays that have been repeatedly pressure tested to 3500 m working depth (Fig. 5). One of the

arrays has been successfully deployed in an Explorer vehicle that has spent several weeks

immersed in sea water with no ill effects. One deployment of the vehicle was for 10 days and

most of that time was spent with the vehicle at depths of 2000 m or more. The Cornerstone arrays

as presently constructed are subject to electronic failure at a depth near 5000 m. This particular

mode of failure is due to one of the integrated circuits crushing under the influence of the extreme

pressure. These sensors are built with the same techniques employed in the 2009 NW arrays and

do not employ pressure cases to protect the electronic components. The construction used in these

arrays appears to successfully meet and exceed the requirements of the NW TDP.

FY 09/10 FY 10/11 FY 11/12

Today

Gear Ships

Test

Build Arrays 2&3

Test Build Array 1

Approvals Contract

Field Trial

Assembly 8 m Assembly 6 m SOR 6 m


Figure 5 Project Cornerstone RDS-based arrays in the back row

with the processor units in front.

Currently, Omnitech Electronics Inc., Dartmouth, NS, is working on the design of an advanced

RDS array for the Norwegian defence laboratory, FFI. This array is intended to be redeployed and

recovered multiple times and to operate for 6-week periods at depths up to 2000 m. The array

design is significantly ruggedized and is intended to allow for storage and recovery on a 1-m

diameter or larger winch drum.

The Norwegian array design will make use of the lessons learned during the Project Cornerstone

effort and will seek to add additional design features to ensure even more reliability. The

Norwegian array will make use of a hydrophone design with connectors that will allow failed

hydrophones to be removed and replaced. The array cable will be a modular component

manufactured by a reputable cable manufacturer. The array cable will have moulded lumps at

each hydrophone location that provide a breakout for the hydrophones to connect to (Fig. 6). This

array will also make use of aluminum pressure cases to ensure reliability at great depths by

preventing the integrated circuit failures under pressure. The transducer will be external to the

pressure case and will make use of well known acoustic transducer construction techniques. An

external casing will be used to protect the delicate hydrophone and the cable moulding. This

casing will have flexible components to allow the rather extended length of the completed

transducer to wrap on a winch drum.


Figure 6 Norwegian array initial design concept illustrating array cable breakout with

hydrophone connected. Courtesy of Omnitech Electronics Inc., Dartmouth, NS, CANADA.

The transducer designs in these two latest projects have provided significant steps forward on the

path to a new design for the NW arrays. The Norwegian array offers many desirable

characteristics and presently offers our best option for a new transducer. However, extended

testing and refinement will be required to meet the needs of the NW TDP. In particular, concerns

about corrosion during an extended deployment will have to be addressed.

3 System Design

This section provides a detailed description of the UWSS without going into low-level technical

matters. The information here is intended to provide the reader with an understanding of the

UWSS components and their roles within the sensor system.

Figure 7 shows an overview of the array system. Two arrays are included in the system. Each

array will be connected to the shore by a telemetry cable. The cable transports control signals to

the arrays and data from the arrays to the shore. The cable also supplies power to the arrays.

The cables will each have a nominal length of 9 km. Transmission of high-rate data over such

long cables is difficult. Each cable will contain two canisters called Repeaters that will amplify

the bi-directional data streams.

The UWSS dry-end will be located in the Science Hut in the Gascoyne Inlet camp. Power to run

the UWSS will be generated at the camp, which will also contain a satellite communications

system providing connectivity with operators in the south.

A data analysis and control station will be established at a location in the south. This station will

probably be established within one of the participating DRDC laboratories.

The remaining sub-sections of this section describe all of the UWSS components.


Figure 7 Overview of the system design.

3.1 Array Design

Each NW array has an overall length of approximately 150 m. The array consists of a polyvinyl

chloride (PVC) pressure canister and a custom cable with hydrophone and other sensor nodes

distributed along the length. The pressure canister, which is partially enclosed in a support frame,

is known as the Array Extender. The Array Extender contains a specialized data stream receiver,

a power management controller, and the DSL modems and switches that drive the telemetry cable

to shore. The array designs used for the 2008 and 2009 NW field trials are described in detail in

reference [1].

The new UWSS transducer arrays will contain acoustic and Depth-Temperature-Heading (DTH)

sensors. Electromagnetic sensors will not be included in the new arrays.


There will be 48 hydrophones in each array. The hydrophones will provide 16-bit resolution

measurements of the acoustic signal sampled at a rate of 2500 Hz. Given the design frequency of

the high frequency sub-array (see below) and roll off of the filter, the resulting signal bandwidth

will be approximately 750 Hz. The lower frequency limit will be between 5 and 10 Hz, while the

upper limit will be at 750 Hz. Useful signal energy will be available in the band between 3 Hz to

1000 Hz.

Hydrophones will be spaced to create three nested sub-arrays, each with 24 or 25 transducers. The

resulting maximum array gain will be on the order of 13 dB for each sub-array.

Following a long-standing convention with RDS arrays, the transducers are numbered from

transducer number 1 at the end of the array most distant from the Array Extender. Each type of

transducer is numbered in an independent series and the transducer type is denoted by a letter or

short series of letters. For example, hydrophones are numbered H1, H2, ... to Hn, where n is the

maximum number of hydrophones in the array.

The longest array aperture corresponds to the lowest frequency band of interest. Hydrophones in

this aperture will be spaced at 5.18 m. This spacing is just slightly less than one-half the

wavelength of the design frequency of 135 Hz. Twenty-four hydrophones are included in this

longest array aperture.

The middle aperture has hydrophones spaced at 2.59 m, which is half the spacing of the longest

aperture section. The design frequency for this section is approximately 275 Hz. Twenty-five

hydrophones are included in this aperture.

The third aperture has hydrophones spaced at 1.295 m, which is again half the spacing of the

phones in the middle aperture. The design frequency for this aperture is approximately 550 Hz.

Twenty-five hydrophones are included in this aperture.

Table 1 lists the hydrophones, their position in the array, and shows which aperture each belongs to.

In addition to the 48 hydrophones, each array will contain 3 DTH nodes. These nodes will be

spaced along the array and will provide measurements of the depth, water temperature, and the

array heading (in three axes). The depth readings will be accurate to approximately 1 m, the water

temperature to approximately 0.5C, and the heading to approximately 1 degree. These orientation

sensors will help to localize the array and ensure that the array lands on the seafloor in a location

that is reasonably flat and close to horizontal.

The custom array cable has a number of twisted-pairs that are used to carry power to the sensor

nodes and serial data streams between the Array Extender and sensor nodes. Multiple twisted-

pairs are generally used to carry the DC power to the nodes. A group of pairs are used to avoid

the stiffness and irregularity in the cable that would result from using a single larger gauge pair.

The remaining data pairs are used for the high-rate serial digital data and control signals. A

minimum of a couple of data pairs are required to support the data streams from the sensors. To

increase array reliability, extra data pairs are employed and the sensor nodes are distributed

between the available pairs. By isolating the data pairs, it is possible for the majority of the sensor

nodes to continue to operate in the event that one data pair is shorted by the ingress of seawater.

Further increases in reliability are possible by including devices that sense a data pair short and


isolate the shorted segment. Such devices have not been used in arrays to date, but will be

investigated for use in the new UWSS arrays.

Table 1 Hydrophones occurring in Low Frequency (LF), Medium Frequency (MF), and High

Frequency (HF) sub-arrays along with their displacements relative to the first hydrophone (H0).

LF (24 H/Ps) MF (25 H/Ps) HF (25 H/Ps) Distance (m)

H0 0.000

H1 5.180

H2 10.360

H3 15.540

H4 20.720

H5 H5 25.900

H6 28.490

H7 H7 31.080

H8 33.670

H9 H9 36.260

H10 38.850

H11 H11 H11 41.440

H12 42.735

H13 H13 44.030

H14 45.325

H15 H15 H15 46.620

H16 47.915

H17 H17 49.210

H18 50.505

H19 H19 H19 51.800

H20 53.095

H21 H21 54.390

H22 55.685

H23 H23 H23 56.980

H24 58.275

H25 H25 59.570

H26 60.865

H27 H27 H27 62.160

H28 63.455

H29 H29 64.750

H30 66.045

H31 H31 H31 67.340

H32 68.635

H33 H33 69.930

H34 71.225

H35 H35 H35 72.520

H36 75.110

H37 H37 77.700

H38 80.290

H39 H39 82.880

H40 85.470

H41 H41 88.060

H42 93.240

H43 98.420

H44 103.600

H45 108.780

H46 113.960

H47 119.140


3.2 Cables

The telemetry cables are made from CELFIL 19 telephone cable. The jacket of this cable is made

from polyethylene and is particularly difficult to bond to. Special treatment of the cable and pot

joints made with Amathane are used to terminate the cable lengths at the connectors. Six 3-km

cable lengths are required. One 400-m long cable is used between the Science Hut and the cable

that heads southward. A 1-km long cable is used between the Science Hut and the cable that runs

to the west. Both of these latter cable segments must be threaded through the foreshore pipe that

protects the cable as it crosses the shoreline.

The CELFIL cable does not include an integral strength member. The cable has a breaking

strength on the order of 700 lb and can be damaged with loads over 600 lb. Care must be taken

when deploying or recovering the cables to ensure that excessive strains are avoided. High current

conditions can exert loads that are a significant fraction of the working load. Deployment and

recovery should be carried out at slack tide.

Although the CELFIL cable is relatively delicate, it has been shown in practice to be more than

adequate for the present purpose. In addition, these cables survive for many years underwater.

At least one spare 1-km length of cable and one spare 3-km length of cable should be provided.

These cable lengths will be used in the event that a cable segment is damaged.

3.3 Repeaters

Four Repeater units are required: two Repeaters for each telemetry cable. The Repeaters are built

from PVC pipe and are housed in frames constructed from type 316 stainless steel. The frames

take the strain during deployment and recovery rather than allowing the connectors and canister

to take the strain. Bend restrictors on the cage prevent the cable from being bent too sharply.

The new UWSS Repeaters (and Array Extenders) will be different from previous Repeaters in

that zinc anodes will be used to reduce corrosion of the frames. Our earlier deployments have

shown excessive and unusual corrosion has taken place on the frames. The use of zinc anodes

sized to provide five years of protection is required. In addition, extreme care must be taken that

all metal parts are in fact type 316 stainless steel. Analysis of the materials in the 2008

construction revealed that some small metal parts and screws were type 304 stainless steel. These

different materials created a galvanic cell that resulted in at least some of the corrosion.


Figure 8 Repeater cages ready for deployment. Completed units are on the order of 2-m long.

3.4 Dry-End

The dry-end of the UWSS is composed of a significant number of components. This section

provides an overview of each component, its key features, and how it fits into the UWSS.

3.4.1 Overview

The purpose of the UWSS dry-end is to:

provide a means for controlling the deployed arrays,

transfer data from the arrays to data processors and a storage device,

communicate with the external System Integration Device, which passes control and data packets to and from the UWSS,

provide automatic target detection and generate associated messages,

process data as required,

turn system components on and off as necessary, and

route data between the components.


The entire Dry-End is intended to be enclosed in a habitat that provides security and environmental

control. At the present time, it appears that the UWSS Dry-End can easily be installed in a single-

or double-wide equipment rack. The rack(s) must be enclosed in an insulated compartment. An

environmental monitor must be able to vent the enclosure or provide heat as necessary.

This habitat will be installed in the Gascoyne Inlet Science Hut. The Science Hut will be unheated

throughout the majority of the year. The hut is expected to protect from the weather conditions

and offer some security for the system. The habitat itself is intended to provide additional

security. Because of the need to provide system physical security the habitat must be

mechanically attached to the Science Hut, have a tough exterior to dissuade vandalism, and a

lockable access.

3.4.2 Remote Control Interface

A Remote Control Interface (RCI) distributes power to selected components, routes signal and

control data between components, and communicates with the external System Integration Device

(SID). Figure 9 shows a block diagram of the potential Dry-End configuration. The RCI is the

central feature of the Dry-End.

Electrical power connections are denoted by 'AC', Ethernet connections by 'E', control signals,

such as a power failure indicator, by 'Ctrl', and the array connections by 'A1' and 'A2'. These latter

two connections could turn out to be Ethernet or USB in the case of the Server/Data Processors,

as could the 'Data' connection on the data store.

The left-hand side of Fig. 9 shows the inputs and outputs from the camp power source and SID.

Two Ethernet ports are shown connecting to the SID. The idea of having two Ethernet ports is to

provide redundancy in keeping with the no-fail approach described earlier. Only a single power

connection is illustrated, but this should also be a redundant supply if possible.

The right-hand side of Fig. 9 illustrates the connections to the arrays and the permanent data

store. Data and control signals will move between the arrays and RCI. High-voltage array power

is supplied by the RCI to the arrays.

The upper side of the RCI is shown connected to an Uninterrupted Power Supply (UPS) and

several Array Receivers. The UPS has a Ctrl line to sense a power fail condition, which should

also trigger a complete system shut-down. Four array receivers are illustrated; however, subject to

design choices only two receivers may be necessary. The number of array receivers will be

discussed in a later section.

The lower side of the RCI is shown connected to four DC power sources. These DC sources

supply high-voltage power to the telemetry cables. Two industrial computers are expected to be

required to support the data management and requests, health monitoring, and auto-detection

capabilities. The term industrial computer, as used here, refers to a computer that is packaged for

embedding within a larger system and capable of sustaining the signal processing loads while

handling any data management requests in a continuous year round operation. These computers

typically have enhanced power supplies and robust components with higher tolerances to

temperature and moisture. Only one of these computers is expected to be active at any one time.

The second is a spare unit to be used in the event that the first fails.


Figure 9 The UWSS Dry-End configuration showing the Remote Control Interface connectivity.

The RCI is not expected to be an intelligent device. The RCI will communicate and respond to

direction by a remote operator. UWSS components will be turned on and off under operator

control by sending commands to the RCI.

3.4.3 Power

The UWSS dry-end receives and conditions power from the Gascoyne Inlet camp generator

system. A small UPS is included to ensure that the UWSS can shut down gracefully in the event

that the main power should fail. The UPS will supply only enough energy for a few minutes of

UWSS operation.

Several high-voltage supplies are included for powering the telemetry cables and arrays.

Typically, 300 VDC is supplied to the telemetry cables. This high-voltage supply helps to reduce

resistive losses in the long cables. DC-to-DC convertors reduce the high-voltage levels to the low

voltages required by the sub-system components.

The DC power supplies that have been used to date have been very inefficient. A considerable

fraction of the total input power has been wasted by these supplies. New power supplies should

be searched for that are capable of low-noise operation with higher efficiency. Four power

supplies are illustrated in Fig. 9, but it may be possible to reduce this to two units if power

supplies with sufficient ratings are available.

Total power input to the UWSS is expected to be approximately 1000 W. This power rating does

not include the electronics and temperature regulation systems of the habitat.


3.4.4 Array Receiver

The arrays connect to an Array Receiver (AR) after passing through the signal switching network

in the RCI. The AR passes control signals to the arrays in command mode and receives high-rate

data from the arrays when they are in data collection mode.

The first AR built in 2008 was designed to handle data from two separate arrays that arrived

through a single telemetry cable. In 2009 the decision was made to put the arrays on their own

dedicated cables. This change meant that only one array could be connected to each AR. The

spare AR was pressed into service and simple software changes allowed the AR to accept data

from a single array.

The new UWSS must evaluate whether it is better to physically modify and adapt internal

software to allow a single AR to receive data from both arrays or whether to simply build two

more of the existing ARs to act as spares. The more elegant and efficient solution is to modify

the AR's to accept the two telemetry cables; however, this could be a more expensive option.

3.4.5 Data Store

The UWSS must include a Permanent Data Store (PDS) that receives all of the data generated by

the two arrays. In normal operation, the PDS will not be required to retrieve data. Obviously, the

PDS must provide this capability, but this functionality will not be the normal mode of operation.

Data stored in the PDS will be retrieved by operators who will physically remove and replace the

PDS after an interval of operation that may be 12 months in duration.

The arrays are expected to operate continuously for the 12-month interval. During this time the

UWSS can be expected to generate 1.55x1013

bytes (~16 TB). In keeping with the no-fail

approach, the PDS should provide at least one independent copy of the data to ensure integrity.

This dual copy will require a 32 TB storage facility.

A 32 TB data storage facility is entirely possible with current technology; however, it is not a

trivial matter. Currently available systems cost on the order of $40,000 and have dimensions of

19 x 8.75 x 26. Power requirements for a system of this size are highly variable, but are likely

on the order of 400-800W. This is 40-80% of the anticipated power budget of the entire system. A

custom data storage solution based on Omnitech's Norwegian Array System is possible and could

potentially require a mere fraction of the power of the commercial solution. Physical sizes and

costs of these systems would likely be similar. An engineering decision will be required.

3.4.6 Server / Data Processor

Two industrial computers are expected to be required to support the UWSS. These computers will

provide the Data Server (DS) and Data Processing (DP) functions required by the UWSS and

operators. Only one of these computers is expected to be active at any one time. The second

computer is intended as a spare that can be activated by the RCI.

The UWSS currently operates in a server/client relationship. User processes are clients. These

processes include data storage, auto-detection, health monitoring, and other functionality.


An expandable auto-detection functionality is a requirement of the UWSS. The exact nature of

the auto-detection process is not currently known, except that it will likely be based on multiple

DRDC Sentinel energy detectors operating on both time and frequency domain data.

A rolling buffer store will be maintained on the DS. A full day of data from the UWSS will

require approximately 44 GB; thus, the rolling buffer store should be able to store at least a

week's worth of continuous data. A server application will be used to manage the rolling buffer

store allowing an operator or a process to request a selected portion of the data.

Data formats for the rolling buffer are expected to be in the raw array data format.

Complete control of the array is expected to be possible through the use of a client application.

This application will simplify the setup, monitoring, and operation of the UWSS by providing

GUI-based input and selection choices.

A health monitoring facility is required. This facility should provide a dual level of monitoring

through the use of software to inspect the incoming data for unusual properties and hardware

signals that indicate failures and improper operations. The monitoring software will inspect the

individual channel data for A/D problems, gain or signal level issues, and other issues. The

hardware signals will indicate power conditions, lack of signal connectivity, and unexpected

voltage and current levels. Because of the intimate relationship with the data streams the health

monitoring may be implemented as a server application or as an application running on the

controller in the RCI.

A client application could be used to supply data to the PDS. The application will be required to

ensure that all available data are saved and should be able to handle exception conditions.

A message generation system will likely have to be implemented as a server application. This

software will handle the generation of informational messages that are sent to the operator.

Typical application of this software would be in the generation of a target detection message, a

health monitoring message, and other similar messages.

Software update capabilities are also required for the UWSS. Both DS/DP software updates and

array firmware updates are desired. Engineering choices will dictate where the codes exist. The

DS/DP update capability may require software on both the RCI and DS. The array firmware

update would likely be best suited to run on the DS.

3.4.7 Southern Analysis Station

To date the NW project has expended no funds on the development of a data processing facility

for the UWSS. The arrays are horizontal line arrays (HLA) and as such are familiar items in the

passive sonar world. Some existing processing suites, such as the Sonar Test Bed and

PLEIADES, already provide many of the standard processing needs of such a sonar. A

PLEIADES processor could easily be modified and added to in order to provide for the needs of

the UWSS.

In addition to sonar processing requirements there are a number of other processing components

that must be developed for the Southern Analysis Station (SAS). These items include: a system


status display, health monitoring, a message generation and interpretation capability, and a data

handling system.

The System Status Display (SSD) is intended to provide the operator with a remotely updated

human-friendly display of the UWSS condition. This display should be based on appropriate

GUI, plots, and indicator components.

The SAS will also require a Health Monitoring (HM) process that automatically collects reports

from the Dry-End HM process and conducts its own evaluation of the received data to ensure that

there have not been issues introduced during the transmission of the data.

A message generation and interpretation process will be required to generate reports and

dialogues for the operator, provide interpretation of the received messages from the UWSS (and

possibly from other NW sensor systems), and to generate messages for transmission to NW

consumers.

The SAS will require a data management capability that allows it to request specific data from the

UWSS and to locally store and organize the messages and data along with processed results. This

type of functionality may require the development of a suitable database along with associated

functions.

A number of Operator Aids should also be provided. A partial list of these might include: a script

editor to allow control scripts for the UWSS to be generated, a rapid system setup capability with

a number of pre-programmed array and dry-end states, a special health monitoring facility to

allow complete system testing, a communications link speed test, a routine to collect a history of

important parameters such as habitat temperature, disk usage, PDS space, etc.

The SAS must be able to open a terminal window on the remote UWSS RCI and DS/DP

processors. A remote computer control program, such as Team Viewer, must also be included to

provide operator maintenance and support of the remote system.

Even the very capable PLEIADES system will require the addition of a number of acoustic

processing routines. For example, line trackers, target trackers, Matched-Correlation Processing

(MCP), cross-bearing localization, and other routines will need to be implemented. In addition,

the SAS should replicate the auto-detection capabilities of the UWSS so that they may be re-run

under operator control.

4 Array Development Plan

This section describes the approach to the development of the new UWSS components. It

assumes that the schedule presented in Section 2.2 is workable. In addition, it focuses largely on

the issues involved with the production and testing of the arrays themselves. The failure of the

arrays in 2009 has localized attention on the mechanical structures and pushed the idea of a

segmented bus architecture to allow for the isolation of portions of the data-pairs in the array

cable that have become shorted due to water ingress.


4.1 Transducer Prototypes

As soon as funding is approved and the amended contract is in place, work will begin on the

development of new prototypes for the transducers. Special attention will be paid to the materials

used in the construction as chemical incompatibility was the major cause of the 2009 array

failures. New hydrophone and DTH nodes will be constructed and tested individually.

4.1.1 Norwegian Array Development

Independent of the NW project, Omnitech Electronics Inc. has arranged for the licensing of RDS

technologies and the sale of a large RDS-based array system to the Norwegian defence laboratory

FFI. This array is intended to be repeatedly deployed and recovered, and will be used in water up

to 2000 m deep. Omnitech and their sub-contractor, Geospectrum Technologies Inc., have

devoted considerable development effort into a new mechanical structure for an array.

Building on the experience from the NW arrays and the more successful Project Cornerstone deep

submergence array, the contractors have come up with a scheme that separates the array cable and

hydrophone node construction. Both components can be tested independently and replaced in the

event of failure.

The basic concept is to create an array cable with breakouts that have connectors to accept

transducer nodes. The array cable will be manufactured by a company specializing in cable

construction thus taking full advantage of the experienced manufacturers. The transducer nodes

will make use of well known techniques that include a mating connector to the cable breakout and

a small pressure case that is integrated with the hydrophone or other sensors. In the case of a

hydrophone node, the transducer will be external to the pressure case and will be constructed

using conventional techniques. Considerable experience is available in the construction of

pressure canisters and hydrophones and this approach takes advantage of that experience. In both

components the influence of the materials is minimized. The cable and transducer node will be

held together and protected at the breakout/transducer locations by the use of a flexible shield that

encloses the transducer node and the moulded breakout.

By blanking the connectors with plugs, it will be possible to repeatedly pressure cycle the array

cable to test for leaks. In addition, the cable can be separately tested under strain and temperature

cycled before being re-tested in the pressure tank. If a cable fails, it can be replaced. If it fails

without sufficient reason, it can be studied forensically and a new cable made.

Similarly, the transducer nodes can be independently tested. They can be exposed to various

heating-cooling, vibration, and pressure cycles. Failed hydrophones can be replaced and failure

modes can be investigated for further development.

The timing of the Norwegian array and the new NW UWSS developments are such that NW can

take full advantage of the testing and experience with the Norwegian array design. The arrays

constructed with these techniques will be more expensive than the resin based modules employed

earlier, but they will be less expensive than traditional array construction and should be much

more robust than the resin arrays. In addition, the ability to replace failed components does open

the door to servicing arrays if they degrade over time.


If NW adopts the new Norwegian array design, then the primary concerns will be ensuring sea-

water ground isolation of the internal electronics as the pressure canisters will be made from

aluminum and ensuring that corrosion is sufficiently slow that the array will last for an extended

interval of deployment. The electrical isolation is also a concern for the Norwegian array and will

likely be a non-issue by the time the NW arrays are constructed. The corrosion issue is less of a

concern for the Norwegians as they will deploy their array for only six weeks at a time. Visual

inspection will allow them to protect any nodes that are suffering from corrosion. The NW array

will not have such a luxury and corrosion tests will have to be conducted to ensure that the

components will survive.

4.1.2 Test Plan

Whatever design is adopted for the NW arrays, testing of the prototypes will be a significant

effort. We must be sure that the nodes will survive in conditions well beyond those expected in an

actual deployment.

Seven main types of testing will be employed to ensure that the prototypes will survive.

1. Pressure testing. Prototypes will be pressure cycled to at least 500-m equivalent depths. A large number of pressure cycles will be used to ensure that failures do not occur.

2. Temperature testing. Prototypes will be temperature cycled a number of times. The electronics and mechanical components will be heated and cooled between +50C and -5C to

ensure survivability.

3. Strain testing. Where appropriate components will be tested under varying strains. This testing is most appropriate for cabling that must support deployment and recovery loads.

4. Adhesion testing. Those components that have glued joints or water-proof assemblies will be tested using strip pull tests to ensure that bonding is complete. Strips will be exposed to

suitable environmental conditions, such as temperature and pressures, to ensure that changes

do not occur.

5. Transducer sensitivity. Transducers will be tested with and without supporting enclosures, in proximity to cable and in free-space to ensure sensitivity remains adequate and constant.

Transducers will be retested after exposure to environmental conditions.

6. Transducer directivity. Transducers will be tested with and without supporting enclosures, in proximity to cable and in free-space to ensure that they have appropriate directivity.

Transducers will be retested after exposure to environmental conditions.

7. Electronic testing. Transducers and other nodes will be examined for current and voltage limits before and after environmental exposure.

4.1.3 Exit Point

The amended NW UWSS contract will contain an exit point following the prototype development

phase. This exit point will be used if it is determined that a robust and survivable array cannot be

constructed within the time and cost limitations of the project.


4.2 Array 1

Once the prototype testing is well advanced and indicating a high likelihood of success, the effort

of constructing a full prototype array will begin. This array will be an exact copy of the arrays

that are expected to be deployed in the NW project. It will have 48 hydrophone nodes and three

DTH nodes. It will be fully functional and will be constructed as a proof of the design concept for

the final arrays.

Once completed, it will undergo extensive testing similar to that employed in the testing of the

individual prototype components. If it passes these tests, then it will be deployed in the water for

an extended period of time. If it fails the preliminary tests, then it will be re-worked to solve the

issues that have been identified and then deployed.

The in-water deployment will likely be carried out in the depth limited water at the DRDC

Atlantic Calibration Barge. This limitation will be imposed by the need to continuously monitor

the array while deployed to ensure operation. Water depth at the barge is approximately 43 m,

which is much less than the final deployment depth of the NW arrays. However, with a long

deployment, water ingress problems should develop if they are going to. Immediately following

recovery, the array will be re-tested in the pressure tank. If the array passes this final pressure

cycling successfully, then we can be reasonably certain that we have met the design requirements.

Array 1 will then become the spare array unit for use in the Arctic should an unforeseen event

lead to a failure of one of the final two arrays. Array 1 will also be used in the integration testing

with the other sensor systems. When the project completes, Array 1 will be available for use in

other projects.

Due to the fact that Array 1 will be used to establish the acceptable limits of testing, it may be

necessary to do some refurbishment of the array to allow it to continue to be used in the

integration testing and to allow it to perform a role as a spare array.

4.2.1 Exit point

In the event that Array 1 indicates that it is unlikely that two more arrays can be constructed that

will survive and be functional in the NW project, then the contract will have the option of being

terminated at this point in time.

4.3 Array 2 & 3

The primary arrays to be deployed in Barrow Strait will be exact copies of Array 1 with any

modifications that have been deemed necessary to ensure system survivability.

These arrays will undergo a test procedure that is designed to test durability and survivability

without introducing flaws. Individual components will have been fully tested for pressure and

temperature prior to final construction. The completed arrays will be exposed to an appropriate

number of pressure and temperature cycles to ensure robustness. Strain tests will also be reduced

to a point that ensures reliability, but that is unlikely to introduce damage.


Additional complete system tests will be conducted on dry land and may also be conducted with

the arrays deployed at the barge. The deployment testing will not be carried out in the same

manner as intended in the Arctic deployments. The arrays will be bagged and gently lowered to

the sea floor. They will not be exposed to stresses of deployment and recovery in order to avoid

risk of accidental damage.

4.4 Spares

As stated earlier, a no-fail approach will be adopted. This means that spares and redundancy will

be made available to the limits of funding.

There will be two arrays in the UWSS and Array 1 will be prepared as a spare unit in the event of

a last minute primary array failure.

There will be three Array Extender units available; one for each of Arrays 1, 2, and 3. The

extender for Array 1 will be used to spare the extenders for Arrays 2 and 3.

Four Repeater units are required for the deployment of the two telemetry cables. One complete

spare will be made available, including the supporting cage and bend limiters. The complete spare

is required in the event of a last minute failure during the deployment process when there is not

time available to wait for substitution.

The telemetry cables required include: six 3-km lengths, one 400-m length, and one 1-km length.

Each length with connectors pre-bonded to the cables. Spares will include: one 400-m length, one

1.5-km length (this is already available with the extra 500 m), and one three-km length. Spares

will have connectors pre-bonded. All cables including spares will have been pressure cycled.

The Dry-End components will all have spares and redundancy as described earlier. The only

single point of failure is the RCI unit. It will be necessary to ensure that this is a robust device

with its own backup capabilities to the limit possible. There will be one or two spare power

supply units, one or two spare Array Receiver units, and one spare DS/DP.

The SAS will also require some spares; however, due to the ease of accessibility parts will be

purchased as required for this device. Only the custom components or those that are difficult to

get will be pre-bought.

4.5 Component Re-use

In order to save costs, components will be re-used wherever possible. Components that may be

re-usable in the new UWSS include: repeaters, extenders, cables, dry-end components, and

processors.

At the present time we have on hand one repeater that was built in 2008. It should be possible to

refit this repeater for the new UWSS. We also have one repeater that was built in 2009. This

repeater requires a new DSL modem. It should be easy to refit this unit.

We have on hand two Array Extenders. Both were built in 2008, but they should be easily refit.


A number of new and used cables are available. We have a new 400-m cable and two new 1.5-km

cables. Both of these should be reusable. We also have two used 3-km lengths of cable. One of

these is slightly damaged, but can be fit with a new connector and should be reusable. The second

3-km cable has some scoring. It may be reusable, but requires thorough testing prior to

acceptance.

The existing Dry-End has two Array Receivers. Both of these can be re-used and/or modified.

The existing Dry-End UPS failed in 2009. It cannot be re-used unless it is repairable. There are

two high-voltage DC power supplies in the Dry-End. These can be reused but they are only 40%

efficient and replacement should be considered.

The existing Dry-End also contains a PC Server. This computer will have to be replaced in the

new Dry-End, but the computer may be of use in the SAS. It will require evaluation.

4.6 Other Components

So far the Array Development Plan has largely been concerned with the Arrays. Other

components are required to complete the UWSS.

Telemetry cables have been discussed, but it has not been mentioned that we are in the process of

constructing a special spool on which it will be possible to wind 3-km of cable. This special spool

is designed to fit within the DRDC Atlantic high pressure test chamber. All cable segments will

be repeatedly pressure cycled to test the cable jackets and potting joints at the connectors. This

testing will ensure that the cables, which have not so far been tested, do not become a weak point.

The new UWSS Dry-End will be a more complicated device than previously. This device will be

designed and built under contract, but it will require significant testing effort. Temperature cycling

will be used to test the device in addition to integration testing and direct communication tests.

The SAS will also be developed under contract. This device will be developed under a contract

that is separate from the other UWSS components.

The final remaining effort is to develop many of the algorithms that will be employed in the

UWSS. Basic auto-detection capabilities already exist as do array element localization and MCP

algorithms. Tracking algorithms and improved detection algorithms are required. This work has

begun at DRDC and will continue in the SAS contract effort.

Health monitoring algorithms were developed as part of the earlier RDS TDP. These will be

resurrected and further developed. The existing HM algorithms were largely concerned with stuck

A/D bits and statistical checks. These will be improved and software will be developed to access

hardware signals that will be included in the new UWSS. The SAS contract effort will integrate

these improvements.


5 Conclusion

This paper has outlined the NW UWSS design concept. It should serve to provide a basic

familiarity with the UWSS and to assist in the development of the amended hardware build SOR.

A detailed analysis has been performed by the Dockyard Lab and DRDC staff to understand

previous array problems, and a number of important issues in the array construction have been

identified. Many of the lessons learned have been successfully implemented in the recent build of

the Norwegian FFI array. The UWSS design presented herein leverages this experience by aiming

to provide a robust array capable of a year-long operation. A modular design is presented which

has the advantage of allowing individual components such as hydrophones and array cables to be

tested separately and replaced, if required. A rigorous testing cycle is given which stresses

components beyond their intended use in order to simulate year round exposure to underwater

Arctic conditions. To satisfy the requirements of the NW TDP new hardware is introduced, in

particular the Remote Control Interface has been presented. Its interaction with the NW System

Integration Device will facilitate the need for data management, health monitoring, array control,

execution of signal processing tasks and communications with the UWSS. Furthermore, a

timeline is given highlighting important milestone dates and the sequence for the build and test of

the arrays. Evidently, a significant effort lies ahead and this document should provide sufficient

information to begin the development of the UWSS.


References .....

[1] Omnitech Electronics Inc., Northern Watch Underwater Sensor System Final Report, Rev 0, Commercial in Confidence, Contract Report, Contract number:

W7707-063616/001/HAL, July 2008


List of symbols/abbreviations/acronyms/initialisms

A/D Analogue to Digital Convertor

AC Alternating Current

AR Array Receiver

AUV Autonomous Underwater Vehicle

CCG Canadian Coast Guard

DC Direct Current

DP Data Processor

DRDC Defence R&D Canada

DS Data Server

DTH Depth-Temperature-Heading

EM Electromagnetic

FFI Forsvarets forskningsinstitutt

GB Gigabyte = 109 bytes

GUI Graphical User Interface

HLA Horizontal Line Array

HM Health Monitoring

LRAB Long-Range Acoustic Bearing

MCP Matched-Correlation Processing

NW Northern Watch

PC Personal Computer

PDS Permanent Data Store

PVC Polyvinyl chloride

RCI Remote Control Interface

RDS Rapidly Deployable Systems

SAS Southern Analysis Station

SID System Integration Device

SOR Statement of Requirement

SSD System Status Display

TB Terabyte = 1012

bytes


TDP Technology Demonstration Project

UPS Uninterruptible Power Supply

USB Universal Serial Bus

UWSS Under Water Sensor System

VDC Volts Direct Current

DOCUMENT CONTROL DATA (Security classification of title, body of abstract and indexing annotation must be entered when the overall document is classified)

1. ORIGINATOR (The name and address of the organization preparing the document. Organizations for whom the document was prepared, e.g. Centre sponsoring a

contractor's report, or tasking agency, are entered in section 8.)

Defence R&D Canada Atlantic 9 Grove Street P.O. Box 1012 Dartmouth, Nova Scotia B2Y 3Z7

2. SECURITY CLASSIFICATION (Overall security classification of the document including

special warning terms if applicable.)

UNCLASSIFIED (NON-CONTROLLED GOODS) DMC A REVIEW: GCEC DECEMBER 2013

3. TITLE (The complete document title as indicated on the title page. Its classification should be indicated by the appropriate abbreviation (S, C or U) in parentheses after the title.)


4. AUTHORS (last name, followed by initials ranks, titles, etc. not to be used)

Heard, G. J.; Pelavas, N.

5. DATE OF PUBLICATION (Month and year of publication of document.)

November 2010

6a. NO. OF PAGES (Total containing information,

including Annexes, Appendices,

etc.)

40

6b. NO. OF REFS (Total cited in document.)

1

7. DESCRIPTIVE NOTES (The category of the document, e.g. technical report, technical note or memorandum. If appropriate, enter the type of report, e.g. interim, progress, summary, annual or final. Give the inclusive dates when a specific reporting period is covered.)

Technical Memorandum

8. SPONSORING ACTIVITY (The name of the department project office or laboratory sponsoring the research and development include address.)

Defence R&D Canada Atlantic 9 Grove Street P.O. Box 1012 Dartmouth, Nova Scotia B2Y 3Z7

9a. PROJECT OR GRANT NO. (If appropriate, the applicable research and development project or grant number under which the document

was written. Please specify whether project or grant.)

9b. CONTRACT NO. (If appropriate, the applicable number under which the document was written.)

10a. ORIGINATOR'S DOCUMENT NUMBER (The official document number by which the document is identified by the originating

activity. This number must be unique to this document.)

DRDC Atlantic TM 2010-248

10b. OTHER DOCUMENT NO(s). (Any other numbers which may be assigned this document either by the originator or by the sponsor.)

11. DOCUMENT AVAILABILITY (Any limitations on further dissemination of the document, other than those imposed by security classification.)

Unlimited

12. DOCUMENT ANNOUNCEMENT (Any limitation to the bibliographic announcement of this document. This will normally correspond to the Document Availability (11). However, where further distribution (beyond the audience specified in (11) is possible, a wider announcement

audience may be selected.))

Unlimited

13. ABSTRACT (A brief and factual summary of the document. It may also appear elsewhere in the body of the document itself. It is highly desirable that the abstract of classified documents be unclassified. Each paragraph of the abstract shall begin with an indication of the security classification

of the information in the paragraph (unless the document itself is unclassified) represented as (S), (C), (R), or (U). It is not necessary to include

here abstracts in both official languages unless the text is bilingual.)

In this document we provide a detailed description of the design of the Underwater Sensor

System (UWSS) that will be used in the Northern Watch (NW) Technology Demonstration

Project (TDP). The test and build cycle of the acoustic arrays is discussed with special attention

given to a thorough testing of the prototype array components and to the prototype array itself.

A modular array design is presented allowing for the independent testing of hydrophones and

cables, thus enabling on-site maintenance of the array and maximizing survivability. A

description of the specific array design is given including array extenders and repeaters along

with suggested modifications as a result of previous years deployments. The components

constituting the dry-end are listed and explained. We introduce the new Remote Control

Interface hardware required to meet the goals of the NW TDP, its primary function will be to

control the various array system components through a communications link with the System

Integration Device. As part of preparing for a continuous year-long operation the required

redundancy of system components and number of spares is quantified. Other areas requiring

further investigation are indicated.

Dans le prsent document, nous dcrivons de faon dtaille la conception du systme de

capteurs sous-marins (SCSM) qui sera utilis dans le cadre du projet de dmonstration de

technologie (PDT) de surveillance du Nord. Le cycle dessai et de construction de rseaux

acoustiques est examin, et porte en particulier sur une mise lessai complte du rseau

prototype et de ses lments. Un modle de rseau modulaire est en outre prsent pour

permettre la mise lessai indpendante des hydrophones et des cbles, et ainsi faciliter

lentretien sur place du rseau et optimiser sa surviabilit. Le document dcrit galement le

modle de rseau, y compris les extenseurs et les rpteurs, ainsi que les modifications

suggres la suite de dploiements antrieurs. Les lments qui composent lextrmit sche

sont rpertoris et dcrits. Par ailleurs, nous prsentons le nouveau matriel de linterface de

tlcommande ncessaire latteinte des objectifs du PDT de surveillance du Nord. Cette

interface servira surtout contrler les divers lments du systme rseau au moyen dune

liaison de communication avec le dispositif dintgration des systmes. Dans le cadre de la

prparation au fonctionnement continu pendant un an, nous quantifions la redondance

ncessaire des lments du systme et du nombre de pices de rechange. Nous prcisons enfin

dautres questions examiner de faon approfondie.

14. KEYWORDS, DESCRIPTORS or IDENTIFIERS (Technically meaningful terms or short phrases that characterize a document and could be helpful in cataloguing the document. They should be selected so that no security classification is required. Identifiers, such as equipment model

designation, trade name, military project code name, geographic location may also be included. If possible keywords should be selected from a

published thesaurus, e.g. Thesaurus of Engineering and Scientific Terms (TEST) and that thesaurus identified. If it is not possible to select

indexing terms which are Unclassified, the classification of each should be indicated as with the title.)

Northern Watch; Underwater Sensor System; Arctic; Array Design; Remote Control Interface; System Integration

Abstract ..Rsum .....Executive summarySommaire ..Table of contentsList of figures and table1 Introduction1.1 Objectives1.2 History1.3 No Fail Approach1.4 Contracting Plan

2 Overview2.1 Deployment Location and Plan2.2 UWSS Schedule2.3 Independent Array Developments

3 System Design3.1 Array Design3.2 Cabl

northern watch underwater sensor system design...

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