Where is FM RDS tone.

No- for the RDS centered at 100.057MHz, you must have the front end tuned for the 100.0MHz channel, and then FM discriminate in a wide enough band to include the 57KHz RDS tone, bandpass filter, and demodulate the bi-phase encoded RDS. See:

Hi,

I think that this frequency fig is the demodulation frequency fig:

am I right?

because I only see there is a tone at 100MHz in my test hardware...

I don't have demodulation function in my test hardware.

Can I still get the FM/RDS deviation by my test hardware ?

or .... can I see any RDS behavior in the frequency variation?

Thank you very much for your advice! Best regards, Boki.

Yes that diagram shows the various signals that FM modulate the FM band channel. Those are the modulation signals.

Then you cannot receive it- just that simple.

No.

You should see a tone at 57KHz offset from center.

Hello Fred,

Easy fix: Go to the next big box store, buy the simplest FM radio they have, one that is the least integrated. Open it, tune it to 100MHz and tap off right at the demodulator. Won't work on some highly integrated or single chip sets. Then I'd try to find an old FM radio at home. One of those 6-10 transistor deals from the 60's or 70's.

How about this one ...

If the RDS turns on, I can see the RDS tone is offset 57KHz to main tone ?

Thank you very much!

Best regards, Boki.

...or the older ones with the thermally stabilized vacuum encapsulated "n-channel" FETs (7-pin and 9-pin variety with the glass seal on top).