The Decca

Text © Copyright Evelyn Simak, February 2016
Images are under a separate Creative Commons Licence.

TG2500 : The Decca (sign) by Evelyn Simak TG2500 : Aerial supports on the wall (detail) by Evelyn Simak

The Decca Navigator system (DNS) was devised in the United States and developed into an operational system by Decca Radio and Television Ltd of London, hence its name. Decca is commonly associated with records and the name is indeed associated with music in that the company's signature tune was formed of the notes d-e-c-c-a, but records formed only a part of the electronic giant's operations. The first use of the Decca name is recorded to have occurred in 1914 when Barnett Samuel and Sons used it for a portable gramophone, called the "Decca Dulcephone"; in 1928 Samuel Barnett's public company changed its name to "The Decca Gramophone Co" and in 1929 sold it to Edward Lewis, a former stockbroker. Decca Records Ltd, trading as "The Supreme Record Company", soon became the second largest label in the world.

In 1936, the American engineer William J O'Brien from Chicago had the idea of developing a method to measure the ground speed of aircraft, originally called "Aircraft Position Indicator" - a position fixing by means of phase comparison of continuous wave transmissions, and he is believed to have developed his version without knowledge of already existing similar systems. However, both the US Navy and Army considered the system too complicated for their purpose. When Robert Watson-Watt, a pioneer and significant contributor to the development of British radar, reviewed and also decided against it, O’Brien sent details of the system to his friend Harvey F Schwartz who at the time (in 1939) was chief engineer of the Decca Record company in England, with the aim to introduce the system to the British military.

By October 1941, the British Admiralty Signal Establishment (ASE) had indeed become interested in the system, code-named "Admiralty Outfit QM", as by then the Admiralty had already started planning the landings in France and required an accurate navigational system. In September 1942, O’Brien brought the Californian equipment to the UK and the first marine trials were conducted between Anglesey and the Isle of Man. More trials followed in April 1943 and in January 1944 before the system was finally approved by the Admiralty. 21 minesweepers and other vessels were fitted with "Admiralty Outfit QM", which on 5 June 1944 was used by 17 of these ships to accurately navigate across the English Channel to clear the minefields in the planned areas which were then marked with buoys in preparation for the Normandy Landings. By 1948, the Decca Navigator system had been approved by 32 countries for marine use.

The Decca Navigator System, as it became known, was a hyperbolic radio navigation system allowing ships and aircraft to determine their position by receiving radio signals from fixed navigational beacons and it consisted of a number of land-based radio beacons organised into chains, with each chain comprising a master station and three slave stations, termed Red, Green and Purple. After 1973, a few chains operated with only three transmitters, usually omitting Purple. The master-slave distance was typically 60–120 nautical miles (110–220 km) and each station in a chain transmitted on a different frequency. There was initially no synchronization between chains.

In 1946, the Decca Navigator Co Ltd was formed and the first chain - Chain 5B (English) - was established in the south-east of England with its navigation system covering the English Channel, the Irish Sea and the southern North Sea. It was through this first chain that Decca's reputation for both accuracy and reliability was established and, as commonly happens with the first of anything, no expense was spared to ensure that it worked properly. Over time, several more chains were established to cover the rest of the UK: 3B (North British), opened in June 1951; 2A (Northumbrian), opened in 1975; 1B (South West British), opened on 29 July 1952; 6C (North Scottish); 7D (Irish); and 8E Hebridean).

In 1950, Decca Radar Ltd, based in Brixton Road, London, and later at New Malden in Surrey, launched its first marine radar, named the "159", after the number of the London bus that passed the Brixton laboratory where the system was designed and manufactured. The marine radar was followed in 1954 by airfield control radar for use with jets, and cloud avoidance radar for use in commercial airliners. Mine sweeping chains were established in Morocco, Tunisia and France and a rent-a-chain business was started with Royal Dutch Shell in 1952. In 1957, a pipeline survey chain was installed between Menorca and the Costa Brava for Gaz de France by Cte Jacques Cousteau with his vessel Calypso. A number of restricted-user chains, one operating in the Gulf of Mexico for the use of oil companies, were set up. A special Decca chain was built in Vietnam for use by the US government; another special chain operated in Europe exclusively for the RAF; a chain on the Christmas Islands was also used mainly by the RAF during Britain's first hydrogen bomb tests (Operation Grapple) conducted in 1957/8. With the onset of systematic hydrocarbon exploration of the North Sea in 1961, Decca also set up a number of so-called Sea Search chains, each chain consisting of a master and two slave stations. The European chains were referred to as Forth (slaves I + II); Fisher (slaves I + II); Forties (slaves I + II); Sea Search I (slaves Red + Green); 6C (slaves Green + Purple); and OE (slaves Green and Purple).

The system expanded rapidly, with Decca Navigator systems eventually operating in more than twenty countries ranging from Australia to Finland and South Africa and covering many of the major shipping areas. More than 15,000 receiving sets were in use aboard ships in 1970, and by 1976 the Decca network had grown to more than 50 chains. The growing popularity of GPS, however, resulted in a decrease of users and the North American chains were switched off in the early 1980s. By 1996 there were only 30 chains left. The Decca system in Europe was shut down in late 1999/early 2000, with the four British chains closing on 31 March 2000. A complete last generation Decca station and a mobile antenna coil house originating from the English master station at Puckeridge are being kept in storage at Trinity House, Tower Hill, London.

In the year 2000, Decca had 21 transmitting sites in the UK, all with unbroken 24 hours/day transmissions and the shifts varying to suit local conditions and the technical installation type. Most slave stations worked 24 or 48-hour shifts with only one operator per shift in latter days, roughly from 1985 until closure in 2000. In the early days, two or three men commonly shared the shifts between them. The buildings housing the transmitters are generally described as having been simple, single storey prefabricated units set on a concrete foundation, comprising the main technical block, a roughly rectangular construction measuring approximately 24 x 9 metres (80x30ft) with a tiled pitched roof; a single storey diesel generator and standby generator house; a vehicle garage; a technical store; a large battery room; a coil hut (near the main tower) and an two fuel tanks, one containing diesel and the other petrol. Some stations were also equipped with an emergency set consisting of a four-wheeled caravan. The engineer in charge and occasionally his deputy were commonly housed on site with their families in standard type bungalows.

The mast and aerial system was of special design and is said to have had an unusually high degree of efficiency at the low frequencies employed. Various types of antennae were used. The early Decca aerial towers were self-supporting 100 metres (325ft) vertical masts of similar construction as the Chain Home radar towers and like these stood on four concrete bases. The towers were later replaced by considerably smaller aerials of only 50 metres (165ft) height. Two slave receiver aerials were mounted on single poles at 9 to 15 metres (30-50ft) height.

SP4355 : Wormleighton by David Stowell SJ2340 : New lease of life by John Haynes HU4542 : Self Catering Shetland by Robbie HU4542 : Old Decca Station, North Road, Lerwick by Mike Pennington HU4542 : Former radio signal station by Lis Burke SJ2340 : Hilltop wireless telegraphy masts by John Haynes

The chains were identified predominantly by their service area and individual sites were commonly referred to by the nearest large town. The overall maximum dimensions of a typical transmitter site were 335 x 210 metres (1100x700ft) but the actual ground area occupied by the station was slightly less than that. Almost all the Decca sites were located in the middle of nowhere. While some of the stations apparently had a name board at the front gate, others had no markings apart from the normal danger and keep out signs, and for as long as they were operational there was also no sign at the entrance indicating what they actually were and what kind of work was done there.

Today, the signs beside the entrance into the Decca station which from the summer of 1946 until the spring of 2000 used to be one of the three so-called slave stations of Chain 5B (English), the first ever operational Decca chain, announce that this is "The Decca". The station was located in the parish of Poringland in South Norfolk on land on the east side of Shotesham Road, leased from Roger W Kidner of Abbot's Farm in Brickle Road, West Poringland. The site's location is roughly equidistant from Poringland in the north and the village of Shotesham, a couple of kilometres further to the south. It is still marked on current maps as being a transmitter station despite it having been closed down for the past 15 years and long since converted into a private dwelling.

Poringland is one of the highest points (49 metres above mean sea level) in Norfolk with only parts of Cromer being higher, making it particularly suitable for the siting of communications and transmitter masts. During the war, the village had been chosen as a site for the development of early radar; at the end of the war a Decca station was established in the area; and in the late 1950s a GPO mast was constructed adjacent to the radar station's Transmitter site, one of the towers of which the MoD still uses. Officially named "Norwich" after the nearest large town, the Decca station served as the Red slave of the English Chain's master station at Puckeridge in Hertfordshire. A second slave station (Green), "Lewes", was located at East Hoathley in Sussex and a third (Purple), "Warwick", at Wormleighton in Warwickshire completed the chain. The original pylon-type tower, later replaced by a smaller antenna system, stood in an adjacent crop field about 150 metres (490ft) due east of the station buildings. Beneath the tower was a 120 metres (400ft) circular earth mat, radiating out from its centre and buried about 60 centimetres (2ft) deep.

Donald W Rayner was one of the first men to arrive at the Decca station when it was opened in 1946 and remained at the station until 1948. He joined John Mears, the station manager, Jerry Proc, the assistant manager, and Norman Thomas, Eric Salter and Steve Stevens. Eric used to operate the "fruit machine" (a complex electromechanical analog computer) at RAF Stoke Holy Cross, the Chain Home radar station, and Steve worked as a ground radar mechanic also at the radar station during the war before both joined the Decca Company.

An aerial view of the site taken by the RAF's photographic unit in 1946, the year the station was opened, shows three small buildings situated on a roughly square plot of land surrounded by a fence. Jerry Proc, then a young man in his mid-20s, recalls that in his time the special receivers were housed in a small building completely encased in fine wire mesh and grounded, and an aerial mounted on its roof. He also reports that they were accommodated in private homes, these being mostly local farm cottages designed for farm workers. A small Fordson van was provided for transport. Requests were made for the provision of appropriate housing but apparently nothing came of it, and eventually Jerry and his wife left the station and emigrated to the United States where they were hoping to find better job opportunities. On the occasion of a visit to the station may years later, in 1996, Jerry, who continued to work for Decca until February 1991, noted that the personnel at that time consisted of only one operator, who lived with his wife in the small on site bungalow. At the time of Jerry's visit activities had been scaled down to a caretaking level, as by then all chains were controlled by the UK Chain monitoring centre in Edinburgh, which had been opened in September 1994 and was referred to as "Super Control".

The bungalow mentioned by Jerry is also remembered by Bill Buckland, who briefly worked at the station in 1966 and again two years later. It was adjoined at right angles by a block housing the technical equipment, with a door linking the two buildings. Bill recalls that the transmitters were housed in the technical block and stood on the wall opposite the French doors. The receivers were grouped by the northern end wall immediately below the external aerials, the supports of which have survived. A picture believed to have been taken at some time during the 1950s, when Peter Bewers was based there, also depicts what would seem to be a control desk against the wall opposite the transmitters.

In Bill's time, a test aerial for monitoring Decca signals had been mounted on tower 1, the southeastern-most tower on the transmitter site of the Chain Home radar station > LinkExternal link. In the 1960s, tower 1, which was of exactly the same design as the three other steel towers on the radar transmitter site, had been shared between the MOD and the GPO, who had an array of microwave dishes and VHF/UHF yagi aerials mounted on it. In 1968/9 a new steel mast of stepped construction > LinkExternal link was built adjacent to the location of tower 1 which was subsequently dismantled. The Decca test aerial, by then long since removed, had been mounted at a height of about 22 metres (75ft) and consisted of a single, approximately 7 metres (20ft) long wire that was attached to a co-axial lead and connected to a monitor receiver housed in a Nissen hut situated beneath tower 1. This hut was demolished when the tower was removed, but a similar Nissen hut is still standing beneath tower 4, the only original tower to have survived. Bill Buckland remembers the test aerial well, because he had been assigned the task of climbing up tower 1 in order to dismantle it, as the test had not been particularly successful. Decca consequently reverted back to using a Landrover unit operating as a mobile monitor. The concrete plinths of tower 1 can still be seen behind the buildings in the fenced-off BT compound.

TG2502 : Radar tower, Upper Stoke by Evelyn Simak TG2502 : Concrete plinth of Tower 1 by Evelyn Simak TG2502 : Nissen hut beneath tower 4 by Evelyn Simak TG2502 : The Plant Room by Evelyn Simak TG2502 : Huts beneath tower 4 by Evelyn Simak TG2502 : Nissen hut beneath tower 4 by Evelyn Simak

A comparison with an aerial view taken in 1999, a year before the Decca station was closed down, confirms that the bungalow and adjoining technical building have survived intact, albeit stripped of equipment and refurbished, and converted into one private dwelling. Even the original French doors and a couple of Crittal windows are still in place. Four old receiver aerial supports can also still be seen. They are mounted on the exterior north wall of the technical block and would seem to be in good condition. All the equipment was duplicated and these four aerials served the slave receivers. They were six metres (20 ft) long fibreglass whips, dated by Bill Buckland to a period spanning from 1967 to 1986 approximately, as earlier versions consisted of wooden 12 metres (40 ft) high crossbar telegraph poles. These aerials were in the late 1980s replaced by active anti-precipitation static (APS) aerials. APS aerials were mounted in homebrew plastic beer barrels which had been coated with a graphite solution in order to reduce the level of the static voltage from the charge on the rain particles.

TG2500 : Former Decca Navigator station by Evelyn Simak TG2500 : Former Decca Navigator station by Evelyn Simak TG2500 : Entrance into the old Decca station by Evelyn Simak TG2500 : On the former Decca station by Evelyn Simak

TG2500 : The Technical block of the old Decca station by Evelyn Simak TG2500 : The Technical block by Evelyn Simak TG2500 : The old Decca station by Evelyn Simak TG2500 : Aerial supports on the wall by Evelyn Simak TG2500 : Aerial supports on the wall by Evelyn Simak

A concreted walkway separated the bungalow from the vehicle garage and the generator house. The garage, which originally had wooden doors, and the adjoining generator plant are still standing, now converted to domestic use. The latter housed two large diesel generators (auto-start Lister or Cummins) and the power distribution switchboard. Jerry Proc recalls that during his time at the station one of the generators was kept running at all times due to frequently occurring power outages. The technical workshop which stood immediately to the east of the generator house can however no longer be seen in later aerial views, indicating that it would seem to have been demolished before the station was closed down.

TG2500 : Concreted walkway by Evelyn Simak TG2500 : Lamp on the vehicle garage by Evelyn Simak TG2500 : Vehicle garage and generator house by Evelyn Simak TG2500 : The generator house by Evelyn Simak

Two fuel tanks, one containing diesel and the other petrol, are mentioned by Jerry Proc who also recalls that the latter was being used for the starter motors mounted on the diesel generators. The generators were later replaced by large batteries housed in a small cabin situated on the edge of the garden, and the redundant generators, as well as the fuel tanks, were subsequently removed. On the occasion of a visit to the station in 1996, Jerry noted that the original steel tower had also since been replaced by a smaller antenna system, although it had as yet to be dismantled. It can in fact be seen still standing on an aerial view dating from 1999 but has since been removed and with it the earth mat buried beneath it, as it would have interfered with ploughing.

A section of the narrow concreted pathway once leading from the station compound to the tower has survived in the garden to the east of the buildings. This pathway covered the output cables and ducting which provided the transmission feeds to the coil hut situated at the foot of the tower. Removable steel covers spaced about every 15 metres (50ft), of which no trace remains, provided easy access to the cables. Although this path today stops abruptly at the back gate, the gate itself is still in place. The strip of concrete marking the course of the path in the crop field, from outside the property fence to where the tower once stood, has since been removed so as not to interfere with ploughing. It can however clearly be discerned in the above mentioned 1999 aerial view, dividing the crop field into two halves with a different crop growing in each.

TG2500 : Concreted walkways by Evelyn Simak TG2500 : Old garden gate by Evelyn Simak

Bill Buckland recalls that his free time at "Norwich" was limited, being allowed only one day per week to buy provisions until a replacement was found to stand in for him. Bill had started working for Decca as a relief engineer under training in 1964 and he was based at the Poringland station on two occasions, the first time in 1966 for the duration of two weeks, helping the Chain Implementation department to check on radiated signal levels. Bill returned to the station in 1968 for a six week stint, allowing for Steve Stevens to take leave for a holiday and for Eric Salter to take some time off for hospital treatment.

Slave stations employed up to three engineers, plus sometimes a handyman for general maintenance; more personnel was employed to man the master stations, and two men each working for Decca's marine service were based at most of the bigger ports. Permanent staff would commonly remain on their station for as long as they wished but relief personnel was continuously required to cover for those who took ill or wished to go on leave at stations all over the country. Bill Buckland's colleagues at "Norwich" were Robin Denyer, Bill White, Harry Cordock, Francis Gurney-Smith and Ray Smith but they too were transient, providing the relief engineer service as and when and where ever required. During this time the whole chain's equipment was however in the process of being updated, reducing the requirement for manpower considerably in the following years.

When, between 1970 and 1979, Bill was stationed at Bolberry Down, the master station for the South West Chain (1B), he once again met Eric Salter. By 1972/3, personnel at the Poringland station had been reduced to Steve as the station manager, and Eric as the assistant manager. In the 1990s, Eric, by then retired, returned to the station once more in a caretaking role. Bill remembers Eric telling him that all the redundant technical equipment had by then been removed from the technical block and was stored in a green portacabin, and that his work consisted of occasionally cutting the grass in the garden.

During WW2, a Gee ("Gee" was the code name for a radio navigation system used by the RAF in WW2) or Oboe (an aerial blind bombing targeting system based on radio transponder technology, using triangulation) semi-portable installation is reported to have been located a short distance to the west of the station, the hardstanding of which is still in place. An aerial view taken in 1946 shows a large shed at this location. The flat roof of the Decca station's generator house can just about be glimpsed, looking east across the adjacent crop field.

TG2500 : View north along Chapel Lane by Evelyn Simak TG2500 : Fields east of Chapel Lane by Evelyn Simak TG2500 : Hardstanding beside Chapel Lane by Evelyn Simak

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Please note that "The Decca" is now a private dwelling and that permission must be sought before entering the property. My grateful thanks go to the current owners for kindly permitting access. I am also very grateful to Bill Buckland for very generously sharing information and memories.

For in-depth information about the Decca Navigator system read: LinkExternal link

For pictures of some of the Decca stations, including three of the English Chain Red Slave at Poringland go to: LinkExternal link

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