I have a Uniden BCD536 HP with the DMR and NXDN upgrades installed. I am trying to listen to a neighboring county highway department that used a VHF NXDN system. I have tried to search with out any luck on audio coming through. Today on two different RAN numbers is receive "NX4 IDS". What does the IDS stand for. I have checked manuals and on line but the IDS question is not answered. Thank you.