On Thu, 02 Aug 2007 08:37:01 -0700, laura halliday wrote:
We have nationwide radio networks in Canada from the CBC,
but don't use RDS. Too many AM transmitters to make it work;
probably other issues too.

Some CBC stations did run RDS for awhile, but I don't recall any of them
using the AF field. (but I only ever saw RDS on the ones that made it
into Tennessee via sporadic-E) I understand they were somehow used in
conjunction with a data-paging scheme, and when that scheme went bust many
of the encoders were shut off.

There really aren't that many AM transmitters left -- offhand I can think
of St. John's (NL), Windsor, Winnipeg, Regina (Watrous), Edmonton,
Calgary, and Vancouver. The four on the Prairies all have FM relays
within the city centre, so I'd imagine the majority of the audience is
listening on FM even there. Apparently you *can* specify an AM frequency
in the AF field - I've seen it done - though while you can direct a
receiver *from* FM *to* AM you obviously can't do it the other way around.

We played with DAB for a while on L band, but have quietly walked away
from it. There's just one multiplex still on the air here in Vancouver.

Yeah, that's unfortunate. Your system provides more choice, better
quality, and no interference to the existing analog service. I suppose
the lack of economies of scale with the U.S. market doomed it. The CRTC
is now considering allowing our IBOC system. (and the CBC has tested it in
Toronto and Peterborough) They seem VERY leery of authorizing it on AM
though.

I've often thought wide band FM ham radio (e.g. 10 GHz) could benefit
from RDS ("VE7LDH 10.2 GHz QTHR QSL via buro").

Interesting idea.

Reportedly some new iPod transmitters include RDS encoders (?!) (along
with some kind of scheme for reading the song title/artist data out of the
iPod) so apparently encoders are available at consumer-practical prices.
The standard is no secret, so someone adequately skilled would probably
have little trouble building one.