On your remote, there should be a button with "TV/RAD" written on it. On my remote, it's located just under the #7 button. Press this button and it should show you if you've captured any radio on the particular satellite you're on. Note you will have to press it again to go back to TV. Hope this helps.
Also, while you're on Radio, you can use the Sat button. And with it you can bring up a list of all stations you've captured on any of the satellites. The same as you can use it with TV.
Al