The feature some of you are referring to where the Police and Fire seem to be changing talk groups is called Trunking. Most radio systems these days are going to it so you cannot follow their conversations for security precautions. If they are transmitting and receiving in the 800 MHz. range, I can pretty much guarantee you they have them trunking and security in the handhelds and mobiles subscriber units is most assuredly enabled. The same goes for their Control stations. Unless you have the right scanner with the proper trunking capability in those areas, you're not tracking squat. The best you will be able to do on a non-secure is follow bits and pieces of a conversation because the system randomly changes which channel it uses to eliminate people accurately following conversations.
I love this app however my area is not listed and being that i dont have a scanner i cant add it so if someone can add my area police/sheriffs dept for me that would be great. I am in NC, Hertford County. I attempted to help with this process by looking on radioreference.com to get some info that you might need to do this.
Hertford County Sheriff:
Frequency License Type Tone Alpha Tag Description Mode Tag
154.74000 KNAO329 RM 203.5 PL Sheriff FM Law Dispatch
154.11500 WPRI451 BM 203.5 PL Sheriff FM Law Tac
155.97000 KNAO329 BM 203.5 PL Sheriff FM Interop
Town of Mufreesboro, NC
Frequency License Type Tone Alpha Tag Description Mode Tag
155.40000 KZV254 RM 203.5 PL Rescue FM EMS-Talk
155.61000 KXC729 BM 203.5 PL Police FM Law Dispatch
156.22500 KXC729 BM 203.5 PL Police FM Law
Tac
Town Of Ahoskie
Frequency License Type Tone Alpha Tag Description Mode Tag
155.40000 KE7831 BM 203.5 PL Rescue FM EMS-Talk
155.43000 KXA275 RM 203.5 PL Police FM Law Dispatch
154.78500 KNNR786 BM 203.5 PL Police FM Law Tac