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
Detuning the 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
1
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 short-
circuit.
• 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.
2
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 replaceable battery pack by stainless steel fastenings. The joint is sealed
against water ingress by an O-ring.
Operation is by a rotating switch ring providing ON, OFF and TEST functions. 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 manner 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 principle of operation
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 wave to return from it, and the direction from which it returns.
A typical ship's radar will transmit a stream of high power pulses 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.
3
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
distinctive pattern is much easier to spot than a single echo such as from a radar
reflector. Moreover, the fact that the SART is actually a transmitter means that the
return pulses can be as strong as echoes received from much larger objects.
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 bandwidth), 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,
where errors are more important, the fast sweeps are also detected. As the first
sweep is a fast one, then the range error is minimised and should be less than 150
metres.
The timescale over which all this occurs is very short. Each "fast" sweep takes
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 pair of dots will be 0.6 nautical 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.
4
Installation
The preferred mounting location is inside the vessel, and protected from the
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 the event it is needed.
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 stainless steel nuts with stainless steel shakeproof washers.
Mount the SART, dome uppermost, onto the bracket by locating the lugs on the
SART pole mount into the slots in the bracket. Push down the SART into place, and
secure with the Velcro strap.
Figure 1
Bracket mounting holes: 4 holes, 5.5mm diameter
.
NOTE: Safe compass distance 1.5m.
5
SART General Assembly
Ring for internal
liferaft mounting
Radome
Operating
switch ring
Battery pack
Lanyard
Mounting
pole
Bulkhead
Mounting
bracket
(Velcro strap omitted for clarity)
Velcro strap
6
Operating instructions
Remove from bulkhead bracket:
Release Velcro strap and lift SART from bracket
To switch on:
Pull the security tab away from the body of the SART
Rotate the switch ring clockwise (ie to the left) to the ON position marked
by “1”
To extend the telescopic pole:
Grasp rubber cover at bottom of pole, and twist the pole to release it in the
pole mount.
Pull the pole down and twist to lock in place in the pole mount
Remove rubber cover from bottom of pole; allow pole sections to drop.
Lock sections together by twisting each section.
To deploy in a survival craft (liferaft):
Extend the SART supporting pole as detailed above
Tether the SART to a suitable point using the lanyard which unwinds from
its base.
Inset the SART through the port in the canopy
Position the bottom of the support pole in the antenna pocket
Secure the pole to the canopy support.
Some survival craft have the SART already packed as part of the inventory. In
general, these models of SART are not fitted with the support pole. The SART
should be switched ON then suspended by its top loop from the highest point of the
survival craft.
Switch ring
Security tab
ON
7
Self test facility
Regular testing of the SART is advised. The duration of the test should be limited to
as short a time as possible as the SART response may be received by other
vessels which are within range.
There are no operational differences between TEST and ON modes; the rotary
switch must be held in the TEST position, on release it returns to the OFF position.
1. Ensure compliance with all applicable Health and Safety instructions when
working in proximity to a radar transmitter.
2. Locate the SART within the line of sight of an operating approved marine
Radar.
3. Rotate the switch ring anticlockwise (ie to the right) to the TEST position, and
hold it in this position.
a) If the SART responds to the radar, the red light in the base of the SART
will be continuously lit and the buzzer will sound every 2 seconds.
b) If the SART does not respond to the radar, the red light will flash every 2
seconds and the buzzer will not sound.
4. Switch off the SART by releasing the switch ring; check that it returns fully to
the OFF position.
Battery replacement
The battery should be changed 5 years from the date of manufacture shown on the
label and routine test procedures should be carried out.
It is recommended that battery change should only be performed by an authorised
McMurdo service agent, in order that a complete assessment and integrity check
can be performed. The replacement battery kit is McMurdo part number 86-630.
Indicator light
TEST
8
Technical description
A single switched antenna is used for both receive and transmit functions; the
switch normally connects the antenna to the receiver circuit. In the standby state
only the receiver portion of the SART is powered to reduce battery consumption to
a minimum. In this condition the indicator circuit causes the LED to flash once
every two seconds.
On receipt of a radar pulse the video amplifier and detector circuit causes the rest
of the circuitry to become active and the unit switches to transmit mode. In this
condition the indicator circuit causes the LED to remain steady and the buzzer to
sound every two seconds.
The detection of a radar pulse causes the switch to connect the antenna to the
transmitter circuit. The output stage is fed by a Voltage Controlled Oscillator (VCO),
whose frequency is determined by a sweep generator. When triggered by the
detector the sweep generator turns on the VCO and causes it to produce exactly 12
forward and reverse frequency sweeps before shutting down again.
If no radar pulses are detected for a period of 15 seconds the unit reverts to
standby mode.
Function chart
SART STATUS BUZZER RED LED
OFF OFF OFF
STANDBY MODE
(TEST or ON) OFF FLASHING
EVERY 2 SECONDS
ACTIVELY
TRANSPONDING
(TEST or ON)
ON
EVERY 2 SECONDS ON
9
Dimensions
10
Operation of marine radar for SART detection
Radar Range Scale
When looking for a SART it is preferable to use a range scale between 6 and 12
nautical miles. This is because the spacing between the SART responses is about
0.6 nautical miles (1125 metres) and it is necessary to see a number of responses
to distinguish the SART from other responses.
SART Range Errors
There are inherent delays in the SART responses; the SART has a trigger delay
and may also have to sweep through the whole radar band before reaching the
frequency of the search radar. At medium ranges of about 6 nautical miles the
range delay may be between about 150 metres and 0.6 nautical miles beyond the
SART position. As the SART is approached the radar delay of the first dot should
be no more than 150 metres beyond the SART position.
Radar Bandwidth
This is normally matched to the radar pulse length and is usually switched with the
range scale and the associated pulse length. Narrow bandwidths of 3.5MHz are
used with long pulses on long range and wide bandwidths of 10-25MHz with short
pulses on short ranges. Any radar bandwidth of less than 5MHz will attenuate the
SART signal slightly so it is preferable to use a medium bandwidth to ensure
optimum detection of the SART. The Radar operating manual should be consulted
about the particular radar parameters and bandwidth selection.
Radar Side Lobes
As the SART is approached side lobes from the antenna may show the SART
responses as a series of arcs or concentric rings. These can be removed by the
use of the anti-clutter sea control although it may be operationally useful to observe
the side lobes as these will confirm that the SART is near to the ship.
Detuning the Radar
To increase the visibility of the SART in clutter conditions the radar may be detuned
to reduce the clutter without reducing the SART response. Radar with automatic
frequency control may not permit manual detuning of the equipment. Care should
be taken in operating the radar detuned, as other wanted navigational and anti-
collision information may be removed. The tuning should be returned to normal
operation as soon as possible.
Gain
For maximum range SART detection the normal maximum gain should be used.
11
Anti-Clutter Sea Control
For optimum range SART detection this control should be set to the minimum. Care
should be exercised as targets in sea clutter may be obscured. Some radar sets
have automatic/manual anti-clutter sea control facilities in which case the operator
should switch to manual.
Anti-Clutter Rain Control
This should not be used when trying to detect SARTs as the SART responses may
be removed by this control. Some sets have automatic/manual anti-clutter rain
control facilities in which case the operator should switch to manual.
Radar Displays
These sketches show the appearance of a SART response at different ranges.
SART response
from distant
liferaft (5-6 miles)
SART response
from liferaft at
medium range (2-3
miles).
Note widening of
“echos”
SART response
close to vessel
(<1 mile).
Display now
shows “rings”
caused by
strength of
signal
12
Technical Specification
FREQUENCY: 9.2GHz - 9.5GHz
POLARIZATION: Horizontal
SWEEP RATE: 5µs per 200MHz nominal
RESPONSE
SIGNAL: 12 sweeps
FORM OF SWEEP: Forward: 7.5µs ± 1µs
Reverse: 0.4µs ± 0.1µs
PULSE EMISSION: 100µs nominal
EIRP: >400mW (+26dBm)
RX SENSITIVITY: Better than –50dBm (0.1 mW/m2) (Note 1)
DURATION: 96 hours in standby condition followed by a minimum 8
hours of transmission while being continuously
interrogated with a pulse repetition frequency of 1kHz.
TEMP RANGE: Operating: -200C to +550C
Storage: -300C to +650C
RECOVERY TIME: Following excitation: 10µs or less
ANTENNA HEIGHT: Greater or equal to 1m (Note 2)
RESPONSE DELAY: 0.5µs or less
ANTENNA BEAM: Vertical: +/-12.5 degrees
Azimuth: Omnidirectional to +/-2dB
WEIGHT: SART only: 360g
SART + pole: 510g
SART complete: 530g
DIMENSIONS: Overall, in bracket: 283 x 101 x 90mm
BUOYANCY: Buoyant
Note
1. Effective receiver sensitivity includes antenna gain.
2. The effective antenna height applies to equipment required to meet
Regulation 6.2.2 of Chapter III and 7.1.3 and 8.3.1 of Chapter IV of
the 1988 Amendments to the 1974 SOLAS Convention.
Standards
Complies with IMO Resolution A.802(19)
Test and Approval Standards are specified on the Declaration of Conformity
following.
13
Declaration of Conformity
14
Declaration of Conformity (page 2)
15
Limited Product Warranty
Subject to the provisions set out below McMurdo Limited warrants that this product will be free
of defects in materials and workmanship for a period of 12 months from the date of purchase.
McMurdo Limited will not be liable to the buyer under the above warranty:-
• for any defect arising from fair wear and tear, wilful damage, negligence, abnormal
working conditions, failure to follow McMurdo Limited's instructions (whether oral or in
writing) including a failure to install properly and/or to use batteries recommended and/or
supplied by McMurdo Limited, misuse or alterations or repair of the product by persons
other than McMurdo Limited or an Approved Service Agent;
• for parts, materials or equipment not manufactured by McMurdo Limited in respect of
which the buyer shall only be entitled to the benefit of any warranty or guarantee given
by the manufacturer to McMurdo Limited;
• for the battery storage life which is specifically excluded from this warranty;
• if the total price for the product has not been paid.
McMurdo Limited does not make any other promises or warranties (express, implied or
statutory) about the product except where the product is sold to a consumer in which case the
statutory rights of a consumer are not to be affected.
In order to be valid, claims must be made under the above warranty in writing as soon as
practicable after discovery of the defect or failure and within the warranty period referred to
above. Proof of purchase will be required. The claim should be sent together with the product
in question to the address set out below or to an Approved Service Agent.
Following a valid warranty claim McMurdo Limited shall be entitled to repair or replace the
product (or part) in question free of charge, or at McMurdo Limited's sole discretion to refund
to the buyer the price of the product (or a proportional part of the price). McMurdo Limited
shall not be liable to a buyer who is not a consumer for any other loss or damage (whether
indirect, special or consequential loss of profit or otherwise) costs, expenses or other claims
for compensation which arise out of or in connection with this product. In the case of a
consumer McMurdo Limited shall only be liable where other loss or damage is foreseeable.
Nothing shall limit McMurdo Limited's liability for death or personal injury caused by its
negligence.
This warranty is to be interpreted under English law.
All enquiries relating to this warranty or Approved Service Agents should be sent to:
McMurdo Limited
Silver Point, Airport Service Road, Portsmouth, Hampshire, PO3 5PB UK
Telephone: Int + 44 (0) 23 9262 3900 Fax: Int + 44 (0) 23 9262 3998
Web: www.mcmurdo.co.uk Email: service@mcmurdo.co.uk
16
User Notes
17
This page contains no other data
18
McMurdo Ltd
Silver Point
Airport Service Road
Portsmouth
Hampshire
United Kingdom
PO3 5PB
Telephone: Int +44 (0)23 9262 3900
Fax: Int +44 (0)23 9262 3998
sales@mcmurdo.co.uk
www.mcmurdo.co.uk
A member of Chemring Group PLC
86-920-001 Issue 1