So I think I learned something about how our cars use RDS data. I suspect the radio actually tunes based upon a database of RDS data transmitted if RDS is on, not a specific frequency.

Sometime last week I was listening to one of my regular stations I have as a preset (It use to display "She" I think as the RDS data). All of a sudden it another station signal cut in for a few seconds and then back and forth between two totally different programs. I thought maybe the station was having technical issue but the problem continued for several consecutive days. Now I noticed the RDS is "Local-05".

I changed the radio to Manual with RDS on and tuned the frequency of the problematic station. With in a few seconds the frequency indicated started bouncing between 96.5 and 106.1 but the RDS data never changed. Both were transmitting "Local-05" if I turned RDS off the problem went away.

Today 96.5 is displaying "Local-10" and 106.1 is "Local-05" and the problem is gone. Anyway I found it interesting the radio tunes based upon the RDS.

I'm open to other explanations.

 

My car sometimes scares me by putting the radio volume into full for a sec or so.

It has happen four times now, and I also suspect that it has to do with the RDS radio signal?

But usually the RDS works great, changing the radiosignal station as driving.

But if your pretuned station fades and the radio doesn't find a other transmitter
for the same station, it might cause some problems.
Especially if there's a strong signal close to.

 

This is the way it works:

You tune a radio station. If the radio station is sending data (RDS), your radio stores the identifier. When your radio detects the signal strenght going under a determined level, the radio:

a) starts scanning for a different frequency with the same identifier if you have the business radio (only one receiver)

or

b) automatically switches to other frequency with the same identifier if you have a professional radio (as it has two receivers, one is receiving the radio program, and the other one is continously scanning frequencies to detect available stations)

A well known issue is when you are in the border of two different radio stations that belong to the same chaine(*), but have different local programs. Let me give you an example:

You are driving in a mountain road where you change frequently from one side of the mountains to the other. In some sections you receive a better signal from radio station A, in other sections, signal from radio station B is better. Both A and B belong to the same chain, so they send the same identifier "ABC". Your radio will be switching from one frequency to the other. If the program is not the same you will be mad... (here in Spain national chains usually disconnect to have some minutes for local advertisers, local news, etc).

The RDS data is dynamic, so sometimes the radio stations change the identifier they send when they disconnect from the "national" program. Sometimes they send other kind of messages and not an identifier (happy valentine's day...) and I learnt in this forum that this is a mess for professional radios...

Hope this helps....

(*) I'm not sure this is the right name in english, sorry. I mean the set of radio stations in different places that belong to the same "owner" .