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AR 88 radio receiver bank
AR 88 machines were used at Y Station Knockholt on the South Downs to pick up German messages using massive rhombic aerial arrays, Whetter told ZDNet UK.
The signals were demodulated and passed through a pen recorder, which produced a trace in a square wave format. Young women were employed to physically read the square wave format, a series of ones and zeros, and translate it into letters. They had to punch out teleprinter tape for each individual encoded letter.
Teleprinter signals were then sent to Bletchley Park via landlines, where Heath Robinson, and then Colossus, worked out the rotor settings used by a Lorenz machine to encode the original message.
Photo credit: Bletchley Park
See more photos of Bletchley Park on ZDNet UK.