Some questions form a RDS's newbie
 

I have read RDS standard EN 500067:1998 several times.Because I am a
newbie in this field and I'm a china student in the university,So I
have few experience in RDS.I hope to search deeply into RDS field.And I
have some questions in he(1)Does RDS is a unhearable signal?If
so,does it means I couldn't hear the music broadcasting station?So it
make me deep into the puzzle now.(2)What I have read is only the
specification,how can I obtain the RDS application's algorithm form
some website or other places?(3)Are there some websites have many
introduction about the application of
RDS?Please forgive me to ask such many question once time.

Bruce Sam wrote:
I have read RDS standard EN 500067:1998 several times.Because I am a
newbie in this field and I'm a china student in the university,So I
have few experience in RDS.I hope to search deeply into RDS field.And I
have some questions in he(1)Does RDS is a unhearable signal?If
so,does it means I couldn't hear the music broadcasting station?So it
make me deep into the puzzle now.(2)What I have read is only the
specification,how can I obtain the RDS application's algorithm form
some website or other places?(3)Are there some websites have many
introduction about the application of
RDS?Please forgive me to ask such many question once time.

Yes, RDS uses an inaudible subcarrier, but it doesn't affect your
ability to hear the normal program audio.

A data signal at 57KHz is mixed with the station's normal music/voice
program. Both signals are broadcast at the same time.

At the receiver, filters prevent the 57KHz RDS data signal from reaching
the speakers. (even if they didn't, you can't hear 57KHz) If the
receiver supports RDS, another filter prevents the music/voice program
from reaching the RDS decoder.

=====

Here in the USA, RDS is generally used to display the name of the
station on the front of the radio, so that the listener always knows
what station they're tuned to. RDS will also often display the name of
the song the station is broadcasting and who's singing it.

There are other things RDS *can* do. It can tell your radio alternative
frequencies - if a station has multiple transmitters, you can
automatically select the strongest signal. It can automatically tune
your radio to a station that's broadcasting emergency information.
These applications are not common in the USA but I understand they are
common in Europe.
--
Doug Smith W9WI
Pleasant View (Nashville), TN EM66
http://www.w9wi.com

Bruce Sam wrote:

I have read RDS standard EN 500067:1998 several times.Because I am a
newbie in this field and I'm a china student in the university,So I
have few experience in RDS.I hope to search deeply into RDS field.And I
have some questions in he(1)Does RDS is a unhearable signal?

RDS is modulated onto a 57Khz ubcarrier and has a bandwidth of about 2.5Khz
- can you hear 54Khz (Not very likely)?
This signal is then added to the MPX stereo signal before feeding the
transmitter.

If
so,does it means I couldn't hear the music broadcasting station?So it
make me deep into the puzzle now.(2)What I have read is only the
specification,how can I obtain the RDS application's algorithm form
some website or other places?

I have a software based stereo and RDS encoder on my website (needs Linux,
Jack, liblo & a compatable 192Khz soundcard). The source is there so grab a
CVS client and feel free to study it.

http://www.spamblock.demon.co.uk/stereogen.html [0]


Regards, Dan.

[0]Yes really!
--
** The email address *IS* valid, do NOT remove the spamblock
And on the evening of the first day the lord said...........
..... LX 1, GO!; and there was light.