Editing Decca Navigator System (section)

=== Decca, Racal, and the closedown ===
[[File:Decca Receiver Philips.jpg|thumb|An ''ap'' Decca receiver Mk II from the 1980s that could be purchased instead of leased. It could store 25 waypoints.]]

The headquarters of Decca Navigator were at New Malden, Surrey, just off the Kingston by-pass. There was a Decca School, at [[Brixham]], [[Devon]], where employees were sent on courses from time to time. [[Racal]], the UK weapons and communications company, acquired Decca in 1980. Merging Decca's radar assets with their own, Racal began selling off the other portions of the company, including avionics and Decca Navigator.

A significant amount of income from the Decca system was due to the receivers being leased to users, not sold outright. This guaranteed predictable annual income. When the patents on the original technology lapsed in the early 1980s, new receivers were quickly built by a number of companies. In particular, Aktieselskabet Dansk Philips ('Danish Philips', ''ap'') introduced receivers that could be purchased outright, and were much smaller and easier to use than the current Decca counterparts. The "ap" versions directly output the longitude and latitude to two decimals (originally in datum [[ED50]] only) instead of using the "deco meter" displays, offering accuracy better than ±9.3 m{{Citation needed|reason=Sources suggest general accuracy was nowhere near this good, more like 100 m|date=September 2023}}, much better than the Decca units. This also eliminated the need for the special charts printed with Decca lanes and zones.

Decca sued ap for infringement and, in the ensuing court battle, Decca lost the monopoly. That signalled the beginning of the end for the company. Income dwindled and eventually, the UK [[Department for Transport|Ministry of Transport]] stepped in, having the [[Trinity House|lighthouse authorities]] take responsibility for operating the system in the early 1990s.

A ruling from the European Union forced the UK government to withdraw funding. The [[general lighthouse authority]] ceased Decca transmissions at midnight on 31 March 2000. The Irish chain provided by [[Bord Iascaigh Mhara|Bórd Iascaigh Mhara]] continued transmitting until 19 May 2000. Japan continued operating their [[Hokkaido|Hokkaidō]] chain until March 2001, the last Decca chain in operation.