The Filter Room, responsible for filtering large quantities of intelligence on enemy activity before it was passed to the operations room, was located in the south end of the underground bunker in Browns Quarry and became operational in 1940.
32.
It was known that the filter room could be overwhelmed by a high volume of reports, and it was a constant complaint that it was a single point of failure in reports from OR and in the RAF and Air Ministry.
33.
They suggested that the filter room at RAF Bentley Priory be devolved down to the Group headquarters to improve the flow of information, but Dowding had already gone a step further and devolved night interception to the Sector level at the airfields.
34.
In the original Dowding system of fighter control, information from the Chain Home coastal radar stations was relayed by phone to a number of operators on the ground floor of the " filter room " at Fighter Command's headquarters at RAF Bentley Priory.
35.
Here, in the Fighter Command's " filter room " at RAF Bentley Priory, operators would plot the map coordinates sent to them on a single large map, which allowed them to correlate multiple reports of the same target into a single track.
36.
Chief among these was the hurried adaptation of the two largest rooms ( now the anteroom and the Ladies room ) into the Operations Room and the Filter Room-moved from its original location in the Crypt bar; the classrooms in the east Wing were converted into accommodation.
37.
This realization led to the development of the Dowding system, a vast network of telephone lines reporting to a central " filter room " in London where the reports from the radar stations were collected and collated, and fed back to the pilots in a clear format.
38.
Located within the building was the Operations Room, Engine Room, RDF Filter Room, Voluntary Air Observer Corp ( VAOC ) Liaison Room, Main Operations Room Dais, Aircraft Movements Section, RDF Supervisors Room, Signal Officers Room, W / T Workshop and PMG Switch Room.
39.
During World War II, the RAF's 9 Group Operations Centre was housed here in three buildings ( Operations Room; Filter Room; Communications Centre ), which were partially buried for protection, similar to buildings in 12 Group, in Watnall, and 13 Group, in Inverness.
40.
As the plotter worked, the targets would be updated over time, causing a series of marks, or " plots ", to appear that indicated the targets direction of motion, or " track " . " Track-tellers " standing around the map would then relay this information via telephone to the filter room at RAF Bentley Priory, where a dedicated telephone operator relayed that information to plotters on a much larger map.
