SSB As A Speech-scrambling Technique
SSB techniques can also be adapted to frequency-shift and frequency-invert baseband waveforms. These effects were used, in conjunction with other filtering techniques, during World War II as a simple method for speech encryption. Radiotelephone conversations between the US and Britain were intercepted and "decrypted" by the Germans; they included some early conversations between Franklin D. Roosevelt and Churchill. In fact, the signals could be understood directly by trained operators. Largely to allow secure communications between Roosevelt and Churchill, the SIGSALY system of digital encryption was devised.
Today, such simple inversion-based speech encryption techniques are easily decrypted using simple techniques and are no longer regarded as secure.
Read more about this topic: Single-sideband Modulation
Famous quotes containing the word technique:
“The audience is the most revered member of the theater. Without an audience there is no theater. Every technique learned by the actor, every curtain, every flat on the stage, every careful analysis by the director, every coordinated scene, is for the enjoyment of the audience. They are our guests, our evaluators, and the last spoke in the wheel which can then begin to roll. They make the performance meaningful.”
—Viola Spolin (b. 1911)