The origin was a corollary experiment to Doppler's premise that waves, whether sound or light or anything else, have compression, or perceived higher frequency, in front of a source moving towards a recipient, and have rarefaction, or perceived lower frequency, behind a source moving away from a recipient.
The original experiment noted was to test the math on how much the perceived frequency shift is. The real experiment was something along these lines: a tuba player was seated on a flat car of a train traveling at a constant velocity and the player playing a steady pitch, usually referred to as @ 75Hz. A second player was seated stationary next to the track playing the same pitch. The experiment measured the heterodyning over time of the two to see if the theoretical mathematics to derive the length of the heterodyning cycle was correct.
https://www.homeworklib.com/question/76 ... eriments-aJupiter JTU1110, RT-82.
"Real" Conn 36K.
