S. In 1941, the Allies made a voice encryption process called SIGSALY which used a vocoder to digitize speech, then encrypted the speech with a single-time pad and encoded the digital data as tones using frequency change keying. This was also a electronic modulation strategy, building this an early modem.[2] https://zanderlpppp.dsiblogger.com/64385606/how-much-you-need-to-expect-you-ll-pay-for-a-good-tv