The AXP340 provides ADS-B out when connected to an approved GPS source.

The ADS-B stream provides own aircraft location information to the ADS-B Ground Station.

The ADS-B Ground Station also needs to know if there is an ADS-B receiver installed.

There are two types of ADS-B receivers available.

Type 1 = 978MHz also called a UAT Receiver. This is the one that can also receive "ADS-B Weather." The Ground Stations only provide FIS-B Weather on this frequency

Type 2 = 1090MHz These receivers will not provide FIS-B weather.

The AXP340 has configuration settings for UAT receiver, or 1090Mhz receiver installed.

This is what tells the ground station what frequency to send it's repeated traffic/weather information out on.

The key to keep in mind here, is that ADS"R" (ReBroadcast) goes both ways.  So, if you have 1090=YES and 978=NO, you will get:

1090 targets on the 1090 frequency and 978 UAT targets via ADSR 978>1090. 

If you set 1090=NO and 978=YES, you will get 978 UAT targets on the 978 frequency and 1090 targets via ADSR 1090>978. 

The only time you lose ADSR is if both are set to YES, or both are set to NO.  

If these settings are left to their default value of "Not Installed" the ground station will not re-broadcast for these aircraft.