It is a tap from the test point. When a digital talkgroup is active, it will output noise.I *think* the OP means the radio will follow digital calls just fine. The radio's audio with be digital noise instead of voice but the radio does *track* calls as they move from channel to channel. If this is the case but DSD isn't working - I wonder if either (a) the OP is NOT using discriminator audio or (b) the Fleetnet system is simulcast - which is a bit harder to decode.
alfonzo - how is the PSR310 audio connected to your computer? Is this headphone audio or disciminator audio taken from a hard wired tap inside the radio?