Chain Home

Chain Home, or CH for short, was the codename for the ring of coastal Early Warning radar stations built by the British before and during the Second World War to detect and track aircraft. The term also referred to the radars themselves, until they were given the official name AMES Type 1 in 1940.Chain Home was one of the first practical radar systems, and the main component of the world's first integrated air defence system, the Dowding system. Operated by the Royal Air Force (RAF), Chain Home radars stretched across the eastern and southern shoreline of the British Isles, looking outward, offering almost continuous coverage of the over-water areas offshore. CH systems would often detect larger formations of aircraft over France, offering invaluable early warning of an impending raid. The presence of radar strongly swung the balance of power in the direction of defence, it was no longer the case that ""the bomber will always get through"".Development began in 1935 after a simple demonstration using a BBC shortwave signal that showed that aircraft reflected radio signals. Robert Watson-Watt formed a team and rapidly developed a usable system using commercial transmitters. Although these were far from ideal for the role, Watt was adamant about delivering a good enough system immediately, as opposed to a better system never. Major development was completed in under a year, and the first five stations covering the approaches to London were operational by 1936. A complete network was ready by the time World War II began in 1939. The network was continually expanded, with over forty stations operational by the war's end.CH was not able to detect aircraft at low altitude, and was soon partnered with the Chain Home Low system, or AMES Type 2, which could detect aircraft flying at minimum altitude level of 500 ft (150 m). This was further refined by the addition of Chain Home Extra Low, or AMES Type 14, which gave cover down to 50 ft (15 m) but at short ranges of only approximately 30 miles (50 km). Late in the war, when the threat of Luftwaffe bombing had ended, the CH systems were used to detect V2 missile launches. After the war they were reactivated as part of the ROTOR system to watch for Soviet bombers.