Re: RDS car radio

[Aaron Read <aread@speakeasy.net>]

At 07:36 AM 4/3/2003 -0800, Bob Nelson wrote:
>Does RDS only work with FM? I don't recall it popping
>up on any AM stations.
>
>I'm guessing the RDS info is somehow encoded into the
>signal, much the way that "closed captions" appear on
>TV; when you have a set that has RDS (or captions)
>they can pop up if you set it right. I'm guessing
>it costs a fair amount of money to do this, which is
>why most stations have "NO INFO".


RDS (aka RBDS) is usually accomplished with a 57kHz subcarrier, so yes - 
it's pretty much limited to the FM band.   The actual cost is very low...a 
few hundred for the subcarrier injector...but the reason why very few 
stations use it is that there's no market for it.  RBS-equipped receivers 
are probably only 5% of all car radios out there.

FWIW, the functions that RDS provides are similar in concept to what the 
"Data services" side of IBOC/HD Radio will do.  The execution is very 
different, and - more importantly - it's being built-in to the system as a 
given, rather than RDS which was always just an optional add-on.   So 
there's a lot more incentive to make use of the data services since 
virtually all radios will have the infrastructure to handle it.



--------------------------------------------------------------------------------------------
Aaron "Bishop" Read             aread@speakeasy.net
FriedBagels Consulting          AOL-IM: readaaron
http://www.friedbagels.com      Boston, MA