Alternative Frequency Switching

[amielec]

Hi all, first what a great product!!
We are having an issue with setting up Alternate freq switching and I am sure it might be a setting issue?
We have two low power FM translators that share same PI code D1F8...this is the PI code set for each location.  One is 106.1 and the other is 92.1....the tuning freq has been set for the unit that it is on.  So for example on the 92.1 unit the tuning frew is 92.1 and the AF is 106.1  and vice versus for the 106.1 unit.
Still it does not seem to be working and I can't help but think we are missing something of have the tuning freq and alt backward.....any incite will be helpful...

thank you!!

[Jan]

The term "tuning frequency" belongs to AF method B only. You should use AF method A as I suppose both transmitters carry the same program for entire day. The AF method B requires to enter the frequency pairs in correct order and also requires that listeners use correct setting of Regional switch on each car radio.

The AF method A uses only one list on each transmitter and each frequency occurs only once in each list. In your example:
Transmitter 92.1:
AF=92.1,106.1
Transmitter 106.1:
AF=106.1,92.1

There's nothing more to be set in the RDS data.

If it does not work well for you, then check:

• whether the AF switching is enabled in your receiver
• whether the RDS level is not too high, causing low error rate in case of bad reception
• in case of changes in AF or PI, tune your station manually by Up/Down buttons and store it again into the car radio preset memory

[Tony Mielec]

Thank you kindly for your response...very helpful!

[Tony]

this information was very helpful thank you!  One other question concerning.  Can I look at the hex code on the RDS spy software and find the switch command?  Also does this work in that two radio station with the same PI code but different RF strengths is the key....so station A has the RDS present as does station B but A is higher RF level and thus it knows to switch?
My challenge is that I am looking for a true and tried method of seeing the AF switch.  The US radio do not all switch and so it is a crap shot....I do have an FM analyzer but think that maybe there is a particular radio or device that might help.
Any advice you might have would be helpful!
thanks again.

[Jan]

My challenge is that I am looking for a true and tried method of seeing the AF switch.

Don't waste your time. It would be nice to see that working but this is not the case of RDS. The AF feature is fully passive in the RDS. That means the RDS only provides to the receivers a list of alternative frequencies. All other functionality must implement the receiver itself, without further support from the FM network. The receiver must find the best frequency, evaluate the reception quality and decide for the switching. The RDS standard does not describe the methodology in more details. As a result, each receiver behaves differently.