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Chelsea Technologies Group
Ltd has extensive expertise in electronics and
acoustics and can custom design and manufacture systems, or elements of
systems. To read about previous
designs click on blue button below:
Other designs include:
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The
Chelsea Technologies Group offers a custom design and manufacture
service for acoustic telemetry systems and acoustic modems. We have
designed and manufactured custom telemetry systems and modems for both
commercial and military customers. Companies
using the Chelsea systems include BAeSEMA and GEC-Marconi as part of
their exercise mines, which are used for training mine hunting crews.
These acoustic telemetry / modem systems are in-service with the United
Kingdom, United States of America, Canadian, Australian and Belgian
Navies. Chelsea Technologies Group telemetry systems have covered
frequencies from 8kHz to 60kHz, and been used for applications such as
data transfer and complex telemetry. All these systems have optional GUI (Graphical User Interface) control systems running under Windows NT4 or 95/98, which have been developed to provide easy control of these advanced acoustic telemetry systems. |
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Sonars for Submarines & Surface Ships |
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The
Chelsea Technologies Group offers a custom design and manufacture
service for sonar systems and sonar system components. Active sonar and
passive sonar systems are supplied for both surface ships and
submarines. These are produced to cover functions such as intercept,
navigation, obstacle avoidance and high power tracking pinger output. Sonar equipment designed and manufactured by the Chelsea Technologies Group Ltd is included in many UK submarines as the outboard components of Sonar 2077. Chelsea also offers technical and logistics support to the UK MOD, DERA, etc. for both in-service and new-generation sonar systems. |
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Towed Synchronised Pingers |
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Chelsea
offers a custom design and manufacture service for acoustic synchronised
pinger and triggered pinger systems. Chelsea
Technologies Group Ltd supply the STAB4 towed synchronised pinger
system, which is used on the BUTEC underwater, tracking range in
Scotland. This advanced pinger system, which was designed and developed
for the UK DGUS, can be towed up to a speed of 25 knots and can be
commanded using acoustic telemetry from a surface vessel. |
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is a fully synchronised system and achieves a timing accuracy of better
than 200 microseconds over its 12-hour battery life. Chelsea
Technologies Group Ltd also supply tracking pingers for use on the Rhona
range in Scotland, this system mounts within the 'sea chest' of
submarines. Torpedo recovery pingers have also been designed and
manufactured for several different torpedoes. |
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Chelsea
Technologies Group Ltd also produces a PC-based portable synchronised
pinger and receiver system, or Distance Measurement Equipment (DME), for
use on submarines or surface ships. This slant range processor and
synchronised pinger system can be interfaced with a vessel's sonar to
provide a synchronised pinger or a synchronised receiver that can
display slant range. |
Slant Range Processor...
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In
DME (Distance Measuring Equipment) mode, VASS can transmit or receive
underwater acoustic tracking pulses. This system is used to measure the
slant range between the towed body of VASS and the vessel under test. So
that the vessel under test can display the slant range a Remote DME unit
is provided which has all the digital signal processing and
synchronisation equipment mounted within a PC.
The configurable parameters are controlled via an easily operated
Graphical User Interface, running under Microsoft Windows 95/98/NT4 |
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The
Chelsea Technologies Group offers a custom design and manufacture service
for sidescan sonar arrays and the electronic and processing systems
associated with sidescan sonar arrays. We specialise in designing and
producing state of the art sidescan sonar arrays and interferometers for
integration into OEM systems. |
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. Sidescan sonar arrays from the simple to the very complex have been supplied to organizations such as Ultra Electronics, C-Max, Sonar Equipment Services and the UK Navy. Sidescan sonar array designs are available covering frequencies between 60kHz and 700kHz. |
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Piezocomposite Sidescan Sonar Array |
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| We recently announced the availability of the first commercially priced piezocomposite high-resolution sidescan sonar array. Offering improved beam pattern stability and ultimately higher resolution than conventional monolithic sidescans, piezocomposites promise to revolutionise the sidescan manufacturing industry. The launching of piezocomposites for imaging sonar follows on from our recent development of high frequency piezocomposites in conjunction with the UK's Defence Evaluation and Research Agency (DERA). | |
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Chelsea Technologies Group, in addition to sidescan sonar arrays, can also design and manufacture acoustic arrays for other purposes such as detection or tracking. |
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POSCOM
is a spread spectrum underwater positioning system developed under the
SeaSense program in collaboration with Subsea 7, Chelsea Technologies
Group, QinetiQ and the University of Newcastle.
A series of trials have been conducted to demonstrate the noise
and reliability performance of the POSCOM system in acoustically hostile
environments. A typical application located two POSCOM beacons on the seabed in proximity of a pipeline bundle tow out, conducted by Subsea 7 tugs. A receiver system was located on a trials vessel that recorded all acoustic signals throughout the trial. Tug spectral noise density was comparable to standard values derived from a similar class of tug whilst spreading losses within the bay approximate to a 20log r spherical spreading model. . |
Datasheet - POSCOM |
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exhibited reliability and repeatability of ranging that would not be
achieved by a standard continuous wave positioning system. Indeed, with
an already proven range accuracy of better than 5cm rms and an 8km range
capability in shallow water with an equivalent source level of
157dB re 1mPa
@1m in a 6kHz band, POSCOM can meet the demands of providing an accurate
positioning system even in acoustically hostile environments. |
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POSCOM
Technical Advantage In terms of noise performance, a pulsed Narrow Band continuous wave (CW) system achieves processing gain by filtering the input signal around the transmission bandwidth. To maximise processing gain, one uses a Narrow Band filter, since this rejects more noise. However this conflicts with the need for the system to have good range resolution. Range resolution is ultimately determined by the transmission bandwidth and so in a conventional Narrow Band CW system the pulses must be short and the receiver bandwidth large to achieve good range resolution. Increasing the receiver bandwidth admits more noise and this in turn reduces the noise performance of the system. The processing gain afforded by a pulsed Narrow Band CW system is unity. Narrow Band CW pulses are subject also to fading in multipath environments that can degrade performance. POSCOM implements pulse compression that overcomes these limitations and provides processing gain determined by the bandwidth time (BT) product of the transmission pulse. In such systems the processed signal to noise ratio is improved by a factor of between BT to 2BT depending on the precise implementation of the receiver processing. POSCOM realises a processing gain in the region of 27dB and operates with a detection threshold between –9dB to –15dB depending on environment. The advantage of using digital waveforms over conventional swept sinusoids such as chirps stems from the ability to exploit a wider signal set whose correlation properties are superior to those of chirps, provided they are processed appropriately. This inherently gives the system a data transmission capability plus superior range and Doppler tracking performance. POSCOM
Capabilities POSCOM
has undertaken several trials during the development program. These
include the Wick noise trial, reservoir trials to access range accuracy
and a shakedown sea trial in Weymouth Bay. These trials have
demonstrated the following capabilities of the POSCOM system.
Range capability of 8km in shallow water with very low equivalent source level of 157dB re 1mPa @1m in a 6kHz band. |
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Chelsea
Technologies Group Ltd |
©2003 Chelsea Technologies Group - The company reserves the right to alter this specification without prior notice.