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AQS901 Sticker

Technical Information

Catalogue No: C1391
Category: Surveillance/Acoustics
Object Type: Promotional Item
Object Name: AQS901 Sticker
Part No: None
Serial No: None
Manufacturer: Unknown
Division: Unknown
Platform(s): Nimrod
Year of Manufacture: circa 1976
Dimensions: Width (mm): 63
Height (mm): 63
Depth (mm): 1
Weight (g): 1
Location: Sticky Badges Box in Cupboard CL (Display 7) [Main Store]

AQS 901


This is a sticker for the AQS901 programme and was produced as stick-on from a backing sheet and there was also a pin-on badge. The Nimrod Maritime Patrol aircraft carried passive sonobuoys which are designed to listen and not emit signals, with the aim of preventing a submarine from realising it is being tracked. The data gleaned from these sonar buoys was transmitted to the Marconi AQS 901 Acoustics Processing and Display System for analysis.

The Company in common with most organisations has a wide range of items promoting the Company name as a form of advertising. The range extends from  'cheap and cheeful'; the sort of thing that would be on the Stand at an Exhibition like the SBAC Farnborough Show. The young visitors love collecting these items along with pictures and Brochures. Such items would include the following:

Stickers, Carrier Bags, Furry Bugs, simple aircraft assembly kits, Cardboard Head Up Display, Drinks Mats. Sometimes a collection of items is put together in something like a Pouch or presentation bag.

A more up-market offering, of better quality, might include:

Mugs, Pens, Key Fobs, Tape Dispensers, Magnifying Glasses, Model cars or the Hybrid Bus, Penknife and Pens.

The top range gifts are usually presented to important visitors or taken on visits to customers and these might include:

Executive Toys, Paperweights, Business Card Holders, Wallets, Clocks, Calculators, Engraved glasses and Glass blocks with a contained model and legend (BAE Systems liked to produce glass Globes to illustrate the global reach of the company). A rather special gift has been a Hologram of a coin.

Ties have been a regular gift in the days when they were regularly worn and were presented as recognition of achievement or membership of a group or ‘club as well as being a promotional gift. Employees for example will be encouraged to wear a T-Shirt with a Corporate Logo which gives a corporate identity. 

The RAA includes items of this type acquired from Suppliers and visits to Customers.


Planning by the MOD for a comprehensive avionics upgrade for the Nimrod Mark I MR ASW had begun in 1975. The Royal Air Force realised that, within ten years of the Nim­rod entering service, advances in Soviet submarine technology would outstrip the MR.l’s systems. The new equipment suite included a Thorn EMI Searchwater radar in place of the aging ASV-21D unit, a new GEC Central Tactical System and the AQS-901 acoustics system compatible with the latest ‘Barra’, Cambs and Dicass sonobuoys.

Thirty-five MR.l were upgraded to the new Maritime Reconnaissance 2 standard, with the first aircraft being redelivered to the RAF on 23 August 1979.

AQS 901 was also fitted to Royal Australian Air Force Lockheed P-3C Orions under a UK/ Australian programme which in­cluded the Australian-designed Barra passive sonobuoy.

The function of the Nimrod ASW system, known as AQS901, was the processing and display of the information received from Sonobuoys. There were  two major subcontractors; Computing Devices of Canada who developed the Fast Fourier Transform (FFT) Analyser and Rank Pullen who developed and provided four chart recorders.

The AQS-901 system ultimately consisted of 20 units of electronic equipment which covered radio receivers, buoy signal processors, computer units, controls, CRT and Hard Copy displays. Both the Nimrod and Orion aircraft carried two complete independent sets of these plus another shared CRT display, control unit and a radio transmitter - 43 items in total. Each aircraft had an acoustics station seating two Sonics Operators and a Tactical Coordinator. Processed information was presented on cathode-ray tube dis­plays and hard copy recorders. Flexibility to handle existing and projected active and passive buoys was built in. The system was based on the Marconi Avionics 920 ATC digital computer with a memory capacity of 256K words. The AQS-901 main computer was a version of the Marconi-Elliott 920 ATC, with a nominal 64,000-word store which is expandable up to 256,000 words. Bulk memory units provide extra capacity. The system converts sonobuoy data for presentation on electronic displays or multi-channel paper recorders.

An important feature of AQS 901 was the Computing Devices Fast Fourier Transform (FFT) analyser. This allowed the constituent fre­quencies of a received signal to be separated and averaged over a short period. Regular noise was amplified relative to random noise, even though the latter may be much stronger at a given instant. The Canadian FFT analyser is able to perform a 2,048 complex trans­form in 11.25 milliseconds. 

The Nimrod AQS901 displayed the processed sonobuoy signal outputs to two operators seated behind two large keyboards with five very high definition CRTs and two multi-function pen recorders. A further component, also supplied by Marconi Avionics, was the very high capacity digital recording system which enabled, amongst other modes, target signature capture and playback either in the air, after landing or when airborne on the next mission.

The Company later developed a cut-down version of AQS90I for the Westland Sea King helicopter retrofit programme and, later still, developed an enhanced system for the Agusta-Westland EH 101 helicopter (now known as the Merlin).’

The scale of the Nimrod acoustic signal processing system was such that Airborne Computing Division had to concentrate on the Maritime aircraft market. The scale of this contract merited the formation, in 1973, of a dedicated Maritime Aircraft Systems Division (MASD) which was prime contractor, with Computing Devices Company of Canada as major subcontractor. This led on to other smaller systems, known as the AQS 902 series, for helicopters and other lighter aircraft which were supplied to a number of different navies, including the Swedish. Starting in 1983, the AQS 902 system was developed into the AQS 903, which went into production in 1985. In 1983, Maritime Aircraft Systems Division (MASD) was the first division of GEC/Marconi Avionics to be awarded the Queen’s Award for Technological Innovation for its successful acoustic processor developments over the past 10 years.


FLIGHT International, 5 April 1980 and with thanks from Simon Lavington’s Book ‘Moving Targets’

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