Existing comment:
Secret Transmissions:
In World War II and the Cold War, some spies communicated with their handlers with specially designed radios. Small enough to be carried easily, these radios could send or receive messages, usually by Morse code.
The problem with special espionage radios was that, if discovered, they would give away their owner's activities. So other spies protected their covers by opting for ordinary short wave radios. |