On Tue, 20 Feb 2018 09:11:26 -0800 (PST), wrote:



2) There are one or two vacant FM radio frequencies, present on the
radio but not used, at least in the USA. Either was a good choice for
my gizmo (since my own car radio isn't new enough to play directly) but
it seemed that the very low frequncy, 87.7 or 9, led to a great lack of
fidelity in the sound. Was this my imagination, since 88.1 works just
fine. It seems like 2 or 4 tenths of a megahertz wouldn't make much
difference.


87.7 and 87.9 are part of TV channel 6 in the US.

If there is an active Digital TV station on channel 6 in your area, you will
get noise.

When TV was analog, you used to be able to hear the sound carrier of Ch 6
at the bottom of the FM radio band.

mark


I used to listen to the Channel 6 TV news in my car, to get the weather
report, when I lived near a city that had a Ch6. That was analog TV. I
was wondering what a digital signal did now, or if tv still used that
low FM band anymore. I no longer live where there is a CH6 tv signal.