Early Live Stereo Radio
I never researched it, I just jumped about, it seems it started in 1924 as AM Stereo, two AM tuners, two AM stations to two mono amps ..
Then RCA (others?) tried AM/FM Stereo Broadcast early 50's, then FM Multiplex.
History[edit]Early experiments with stereo AM radio involved two separate stations (both AM or sometimes one AM and one FM) broadcasting the left and right audio channels. This system was not very practical, as it required the listener to use two separate receivers. Synchronization was problematic, often resulting in "ping-pong" effects between the two channels. Reception was also likely to be different between the two stations, and many listeners used mismatching models of receivers.
After the early experiments with two stations, a number of systems were invented to broadcast a stereo signal in a way which was compatible with standard AM receivers.
FM stereo was first implemented in 1961. In the United States, FM overtook AM as the dominant broadcast radio band in the late 1970s and early 1980s.
Timeline[edit]- 1924: WPAJ (now WDRC (AM)) broadcast in stereo from New Haven, Connecticut, using two transmitters: one on 1120 kHz and the other on 1320 kHz. However stereo separation was poor, to preserve compatibility for mono listeners.[1]
- In the 1950s, several AM stereo systems were proposed (including the original RCA AM/FM system which later became the Belar system in the 1970s) but the FCC did not propose any standard as AM was still dominant over FM at the time."
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AM Stereo still exists
https://en.wikipedia.org/wiki/AM_stereo
