[BC] We did choose the right FM system

[Robert Orban]

At 10:00 PM 12/24/2005, you wrote:
>From: DANA PUOPOLO <dpuopolo at usa.net>
>
>Nope!
>
>By far the best FM stereo system was an FM on FM system (Crosley?).
>It only degraded the s/n by 6 db (as opposed to the 23 db degradation the one
>we have does). Its only problem was that it was incompatible with SCA's, and
>the industry wanted that $$$ at the time.
>
>America's broadcast record of screwing up everything technical is
>unblemished!

Because the FM subcarrier in the FM/FM system was narrowband, there 
was not enough spectrum available for it without truncating the 
spectrum. This would have built nonlinear distortion into the system 
spec, which never could be improved by hardware improvements.

The 6 dB loss you recall was _mono_ S/N because the FM subcarrier was 
always taking up baseband modulation even when there was no L-R 
energy. I don't recall the FM/FM's noise penalty in stereo, but it 
was a lot more than 6 dB because narrowband FM does not have the same 
SN advantage as wideband FM.

The BTSC went through the same exercise comparing an FM/FM system 
(EIAJ) to a suppressed carrier AM system and once again, the 
suppressed carrier AM system proved superior. (This time, the 
subcarrier was companded to reduce the stereo SN penalty substantially.)

We DID choose the right FM stereo system.

Bob Orban