Orolia S4 1 User Manual

S4

RESCUE SART

Search And Rescue Transponder

User Manual

CONTENTS

Warnings....................................................................................1

General description...................................................................2

SART principle of operation.....................................................2

Installation .................................................................................4

SART General Assembly...........................................................5

Operating instructions.............................................................. 6

Self test facility..........................................................................7

Battery replacement ..................................................................7

Technical description................................................................8

Function chart ...........................................................................8

Dimensions................................................................................9

Operation of marine radar for SART detection......................10

Radar Range Scale..................................................................................10

SART Range Errors..................................................................................10

Radar Bandwidth......................................................................................10

Radar Side Lobes.....................................................................................10

Detu n in g th e Radar..................................................................................10

Gain.........................................................................................................10

Anti-Clutter Sea Control............................................................................11

Anti-Clutter Rain Control...........................................................................11

Technical Specification...........................................................12

Declaration of Conformity....................................................... 13

Limited Product Warranty.......................................................15

Warnings

• This SART is an emergency device for use only in

situations of grave and imminent danger.

• False alarms cost lives and money. Help to prevent them;

understand how to activate and disable your equipment.

• Read the complete manual before installing, testing or

using the SART.

• The SART contains no user servicable parts. Return to your

dealer for service.

• Dispose of this device safely. Contents include Lithium

batteries; do not incinerate, puncture, deform or short­circuit.

• This device emits radio frequency radiation when activated.

Because of the levels and duty cycles, such radiation is not
classed as harmful. However, it is recommended that you
do not hold the radome while the SART is activated.

• The battery in this device is rated Class 9 for transportation

purposes. Ensure compliance with all applicable
regulations.

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General description

The SART (Search And Rescue Transponder) is designed for survivor location
during search and rescue operations.

CARRY-OFF SART

Supplied as one integral unit. This is normally mounted in a bulkhead bracket
(supplied) which is used to stow the unit on the mother vessel. On abandoning to a
survival craft the SART can be carried in one hand off the stricken vessel and
mounted through a port in the canopy of the survival craft using the telescopic pole.

The main body of the SART is high visibility orange thermoplastic, attached to the
sealed r epla ceable battery pac k by st ainl ess st eel f asten ing s. The joint is sealed
against water ingress by an O-ring.

Operation is by a rotating switch ring providing ON, OFF and TEST func tions. The
ON position is reached by breaking a security tab. The switch ring is spring loaded
so that it returns automatically from the TEST position.

The Lithium battery is fitted with internal overload protection and has a five year
storage life. Non-reversible electrical connections are provided in the SART body
and battery pack to facilitate battery replacement.

Each SART carries a unique serial number on the label on the orange body.

LIFERAFT SART

Supplied with or without mast. Normally is packed as part of the liferaft equipment.
The mast version is mounted in the same manne r as the carry-off version; the
version without the mast is intended to be hung from the highest point inside the
liferaft.

The SART itself is identical with the carry-off version.

SART princip l e of oper a ti on

Actuating a SART enables a survival craft to show up on a search vessel's radar
display as an easily recognised series of dots.

RADAR (radio detection and ranging) is a device carried by most ships which is
used to determine the presence and location of an object by measuring the time for
the echo of a radio w ave to return from it, an d the direction from which it returns.

A typical ship's radar will tran smit a stream of high power puls es on a fixed
frequency anywhere between 9.2GHz and 9.5GHz. It will collect the echoes
received on the same frequency using a display known as a Plan Position Indicator
(PPI), which shows the ship itself at the centre of the screen, with the echoes
dotted around it. Echoes further from the centre of the screen are thus further from
the ship and the relative or true bearing of each echo can be easily seen.

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The SART operates by receiving a pulse from the search radar and sending back a
series of pulses in response, which the radar will then display as if they were
normal echoes. The first return pulse, if it sent back immediately, will appear in the
same place on the PPI as a normal echo would have done. Subsequent pulses,
being slightly delayed, appear to the radar like echoes from objects further away. A
series of dots is therefore shown, leading away from the position of the SART. This
distincti ve pat tern i s much easier to spot than a single echo such as from a radar
refle c tor. Moreover, the fa ct tha t th e SART is actually a tra nsmit ter mea n s th at the
ret urn p ulses can be as st rong as ech oes r eceiv ed from much larger o bjects.

A complication arises from the need for the SART to respond to radars which may
be operating at any frequency within the 9GHz band. The method chosen for the
SART is to use a wideband receiver (which will pick up any radar pulses in the
band), in conjunction with a swept frequency transmitter. Each radar pulse received
by the SART results in a transmission consisting of 12 forward and return sweeps
through the range 9.2GHz to 9.5GHz. The radar will only respond to returns close
to its own frequency of operation (ie. within its receive bandw idth), so a "pulse " is
produced at the radar input each time the SART sweep passes through the correct
frequency.

A slow sweep would give the radar a stronger echo to deal with as the sweep
would be inside the operating bandwidth for a longer period. The delay for the
sweep to reach the operating frequency may however lead to an unacceptable
range error, as delayed echoes appear to be coming from more distant objects.

To minimise this problem, the SART uses a "sawtooth" response, sweeping quickly,
then slowly for each of its twelve forward and return sweeps. At long range, only
the slow sweeps, giving the strongest returns, are picked up. At close range,
wher e errors are more im portant, the fast sweeps are also d etected. As the firs t
sweep is a fast one, then the range error is minimised and should be less than 150
metres.

The timescale over whi ch all this occurs is v ery short. Each "fast" s w eep ta kes
about 0.4µs, each "slow" sweep about 7.5µs. The complete series of twelve
forward and return sweeps is therefore complete within 100µs. Displayed on the
PPI, the spacing between each pai r of dot s will be 0.6 nautica l miles.

On a long range setting, a typical radar will be triggering the SART every
millisecond - but only during the period that the rotating radar scanner is pointing in
the correct direction. Most modern radars use sophisticated noise rejection
techniques, which prevent the display of echoes which are not synchronized with
the radar's own transmissions, so one radar will not normally be confused by a
SART's response to a neighbouring radar.

The SART indicates that it has been triggered by lighting an indicator LED
continuously (it flashes in standby mode) and by sounding an integral buzzer. If no
radar pulses are detected for a period exceeding 15 seconds, the SART reverts to
"standby" mode.

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Installation

The p referred mo unting location is insi de th e vess el, and pr otected from t he
elements, usually on the ship’s bridge wing. The SAR should be mounted where it
will not get in the way of day-to-day operations, but where it can readily be
accessed near an emergency exit in th e event i t is n eeded.

Do not install the SART within the ship's radar beam.
Fix the mounting bracket to a bulkhead in a convenient location. The recommended

fixing is by M5 marine grade stainless steel (eg A4/316) bolts; length is dependent
upon application. The bolts should be secured with either stainless steel locking
nuts or stain less steel n uts with stai nless s teel shakepro of washer s.

Mount the SART, dome uppermost, onto the bracket by locating the lugs on the
SART pole mount int o t he slots in the b rack et. Push down the SART i nto plac e, and
secure with the Velcro strap.

Figure 1

Bracket mounting holes: 4 holes, 5.5mm diameter
.
NOT E: Saf e comp ass di stan ce 1.5m.

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