A Strange Fish Caught In early 1940, the British intercepted a strange kind of radio signal. It wasn't Morse code. It used the teleprinter code system used by news wire services and was encrypted. The British called this code "Fish." Fish used the Baudot code, which represented letters and numbers as a series of five binary symbols. "A" was 00011, "B" was 11001, and so on. Fish took each letter and added an obscuring letter to it, using base-2 math. A 00011 + + B 11001 = = G 11010