David,

David Eduardo schreef:
Right, but RDS would make a good low cost starting point for an expanded
FM
text service. And we'd have it, if somebody thought there was real money
in
it.

Nobody wants to fight for RDS as it has no competitive advantage and is not
applicable to AM. As I said, it was developed for European simulcasts to
allow automatic signal seeking, which is not an issue in the USA.

It can also be used for other applications.

In Brussels, there is a service where all signs on the busstops are
dynamically updated based on the real possition of the busses. The
information broadcasted by the central server of the bus-company to
update the signed is done in a RDS channel of a FM station.

Another applications are DGPS and TMC (real-time road traffic
information) which are broadcasted over FM/RDS.



BTW. There is now also a AM-version of RDS: AMSS.
See he http://www.ebu.ch/en/technical/trev/trev_305-murphy.pdf

It's already in use by the BBC WS (on 648 Khz on MW and on SW) and by
RTL (234 Khz LW).
There are not a lot of receivers which use it, but the new FM/AM/DAB/DRM
receiver of Roberts does.
http://www.drmrx.org/forum/showthread.php?t=1411




These kind of systems have been in use for quite a long time now.
The LW-transmittor of France Inter (162 Khz) is used to broadcast
time-signals (actually the same format at the DCF77 transmittor in
Germany but with a different modulation-sceme).
The BBC radio4 transmittor at 198 Khz is used to control (IIRC) day- and
night-tariff for electricity.



Cheerio! Kr. Bonne.