Quote:
Originally Posted by bandersen
In addition to the split sound IF Phil mentioned, some early RCAs used a Foster-Seely discriminator rather than a ratio detector. Due to a lawsuit with Armstrong I believe.
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RCA NEVER used a limiter-discriminator in ANY of it units. It designed and employed the ratio detector in an attempt to screw Armstrong out of patent royalties, which resulted in a lawsuit by Armstrong against RCA.
If you haven't seen Empire of the Air, I highly recommend it. It tells the entire story in great detail with great accuracy.
RCA, like most manufacturers, used the split sound system for many years, but RCA hung onto it a bit longer than most because intercarrier sound was a General Electric development, and RCA would have to pay patent royalties.
Split sound worked well until the mid 50s because until then, pix carrier power and sound carrier power were equal. In the mid 50s, most stations realized that not as much sound carrier power was needed for equivalent coverage, and went to sound at 50% of visual. Later, in the 60s, it was determined that sound carrier power could be reduced even further to 10-20% of picture carrier power BECAUSE most sets had intercarrier sound by this time. While it did work well with intercarrier sets, each reduction in power resulted in a loss of volume at the split sound receiver.
Most STBs will maintain their sound carrier at the RF output at 10% of the pix carrier level. So, the problem has crossed over in the digtal age.
I hope this helps.