Ben, I'm curious are you hearing traffic from the western side of the state ? Just wondering if the talkgroups are set up for local, regional or statewide coverage. Unfortunately I am out of range of the Pittsburgh site and haven't located any closer to me.
Dan,
My understanding of the system is that talkgroups only appear on a site where there is a radio affiliated with that site and that radio is requesting the particular talkgroup. With only 10 sites statewide, this makes things pretty difficult to map out. I have only picked up nat guard aviation assets from FTIG and I don't get them all the time. I do sometimes also hear the fire dept from FTIG entering and exiting the runway area. FTIG is firmly in the footprint of the Reeser's Summit site and last time I was there, I noted a strong signal from that tower all over the base. So, units are usually going to affiliate there first Since the tower site I can receive from home is the Geigertown site to the southeast of FTIG, I think I only hear traffic when one of the birds gets high enough or east enough to affiliate with Geigertown.
There are still two sites that remain unlocated. I would imagine at least one of those must be near Erie. Not sure where the other would be. The "Pittsburgh" site for the 700 system is probably colocated at this location based on the few signal reports I have seen:
Harrison City (WEST03) Site Details (Pennsylvania STARNet) Not sure about that, though. Somebody should take a ride near there with their antenna disconnected and see if they can get a copy on the 700 control channel. If so, then this is the location. If not, it's another high profile tower site to the west or north.
Johnstown is in between Everett and the Pittsburgh area site. So, I would think that when in the air, the helos from there would have solid coverage from either. On the ground...I don't know. But, it seems like the helos there maybe don't use the trunked system too much if you're hearing them regularly on the lowband still. Out this way, when I do hear the helos, they are usually just making a quick radio check with "ops" on the already listed PANG talkgroup. Typical military comms...short and to the point.
EDIT:
Forgot to mention that I sometimes go two weeks or more with no traffic. I have a receiver dedicated to monitoring the Geigertown site and recording audio as I try to figure the system out. I once left a receiver in the Harrisburg area for a week recording Reeser's Summit and got absolutely nothing all week. That surprised me since I always figured that site would be the busiest of all with Harrisburg/ Cap City Airport/FTIG in the footprint. Use of this system is exceedingly sparse...tracking it would be pretty boring for the average "scanner fan".