Comprehensive Display System
The US Navy purchased a prototype CDS and produced twenty of their own version, the Electronic Data System (EDS).
The basic idea of the CDS was extremely influential in military circles and led to computerized versions in the form of DATAR, Naval Tactical Data System, and SAGE.
[4] Although the initial concept was to net ASDIC data, in 1947 attention turned to the aircraft plotting problem;[5] toward the end of the Second World War, Allied non-automated fighter direction experienced saturation and degraded performance when subjected to Kamikaze attacks.
[7] The first complete system for the aircraft role was demonstrated at Elliott's Borehamwood research center in June 1950.
This eventually led to a contract for two prototype versions; the original prototype was delivered as "X1" to the Admiralty Research Establishment in Witley in 1951, and a second newly built model, "X2", which was paid for by the US Navy's Bureau of Ships but officially on permanent loan to the US Naval Research Laboratory.
[9] Starting in 1949, the British Army began development of a new tactical control radar that would provide early warning and putting-on information for up to sixteen dispersed batteries of anti-aircraft artillery spread over a city-wide area.
This presented the same sort of problem that the Navy faced with its dispersed destroyers; the AA guns had small radars on-site, but these did not provide a long-range picture of the battle as a whole.
A third set of operators handed separate height-finding radars (if used) and the identification friend-or-foe interrogators, feeding that information into the system on a less frequent basis.
They also found it to be sensitive to changes in temperature, lacking precision, and given its large number of moving parts, difficult to maintain.
A final problem was that they desired a system capable of tracking hundreds of objects, not dozens, and adding the additional channels to the CDS would be expensive.
The first was installed on USS Willis A. Lee in 1956, then on the four ships of Destroyer Division 262, and as well as a selection of guided missile cruisers.
One of these was proposed by the University of Michigan's Willow Run Research Center, who suggested adding a data transmission system to CDS.
[21] Ultimately the Air Force continued with the original SAGE development, whose AN/FSQ-7 computers were the largest ever built.
These signals were sent to the deflection plates of a separate channel in the cathode ray tube display, overlaying a dot on the existing radar imagery to provide a cursor.
[8] The value of those internal potentiometers was also sent back to the input consoles, creating a "blip" on the screen that matched the underlying radar data, but did not move.
By rapidly cycling through the potentiometers, the beam in the display caused a series of spots to appear on the screen, representing the location of the (up to) 96 targets.
The operator could select different sets of targets to display, only the high altitude ones for instance, or only friendly aircraft.
[5] The original CDS concept used a complex set of motors and potentiometers to encode data, which was difficult to keep running properly.
In their place, the original radar blip was displayed, but surrounded by additional data in the form of two-digit numbers.
This allowed the system to have a global track number across the task force while each receiving CDS could assign it to a different local ID.
This version also added additional inputs that transmitted readiness information from the aircraft carriers and missile cruisers, allowing the intercept officers to choose what weapons to assign to a given target.
They further modified their units by replacing the trackball with an electrically conductive sheet of glass which the user pressed on with a metal probe.
