P25 System with VHF/UHF/800 Frequencies on the same site

[CqDx]

Recently I noticed the Millstone Nuclear Power Station in CT has a P25 System. The interesting part of this discovery is I have never seen a P25 system with VHF, UHF and 800 MHz frequencies all within a set of possible secondary control channels and voice channels within the same RFSS and Site. Please see attached for the DSD Plus decode screen.

At first I thought this is just a test setup, but the license does indicate this is indeed assoicated with proper licenses on all three bands.
VHF/UHF Frequencies WQYV405
800 MHz Frequencies WPEQ767

I suppose the zone controller will only allocate voice radios based on the subscriber radio IDs associated with what frequency band the radio operates in. Unless all radios used on the system are tri-band radios.

 

[GTR8000]

Dominion North Anna Power Station Trunking System, Centerville, Virginia

Dominion North Anna Power Station Trunking System Profile

www.radioreference.com

 

[slicerwizard]

So how does a VHF or UHF radio get service? There are no active VHF or UHF control channels indicated in that screen shot.

 

[mmckenna]

It would be odd/awkward to have the system made up of VHF, UHF and 800MHz channels all in one single system at two very closely spaced sites..
What it's likely doing is (read: My guess from looking at the licenses, sites, build out dates, etc):
800MHz trunked system WPEQ767 800MHz trunked system. Has a few talkgroups on it for plant maintenance, security and training, probably more that are not in the database.
VHF system is 2 2 channel sites
UHF system is 2 2 channel sites.

All are licensed for P25 Phase 1 and Phase 2.

Dominion Energy has a security talk group on the Waterford Regional Trunked system.


My guess:
800MHz for plant operations
VHF for other agencies to monitor/respond
UHF for other agencies to monitor/respond
Maybe the company itself uses different bands at different sites, and having a VHF + UHF + 800MHz system available for anyone that shows up.

But I suspect you'll find a control channel on 800MHz. A control channel on VHF and another control channel on UHF.
The 800MHz system was built out way before the VHF and UHF systems were.

 

[KevinC]

Why does it show two different system ID’s in your screenshot? One MSI and the other probably Harris.

 

[CqDx]

The data above 92822.00A (11:08:04) was from an earlier decode and can be ignored.

 

[Echo4Thirty]

Being a utility, I would guess that there is no call for interoperability or any other 'agency' coming to talk on it. That said, it is conceivable that they have multiband radios and chose to use their licenses on V/U and 8 for one system. Their radios wouldn't care and would just go to the channel that has the grant. No reason it wouldn't work on paper or be any different than any other 7/8 system in the way it handles CHIDs and channel grants.

Now real world, Why do this??? Depending on the location of the subscriber you could have VASTLY different inbound/outbound coverage depending on the band/channel you trunk to. How could you EVER balance out the system repeaters/coverage? If they are indeed doing a single site V/U/7/8 system, this would be an engineering nightmare and I cannot fathom it has ANY advantages to offset the complexity.

I was thinking the same thing that MMcKenna was but I do not see any active CCs being broadcast by this site on V/U yet the SCCs are there.

 

[tunnelmot]

If they are indeed doing a single site V/U/7/8 system, this would be an engineering nightmare and I cannot fathom it has ANY advantages to offset the complexity.

Thats what I was thinking lol

 

[mmckenna]

I was thinking the same thing that MMcKenna was but I do not see any active CCs being broadcast by this site on V/U yet the SCCs are there.

The coverage differences between VHF, UHF and 800MHz would make the system absolutely suck if the control channel was only on 800MHz. There would be plenty of places where VHF and UHF might technically work, but since the 800MHz control channel would not be heard, the radio wouldn't know where to switch to.

That's what made me think the VHF system was stand alone, the UHF system was stand alone and the 800MHz system was stand alone.

Other thing that popped into my mind was that other agencies in that area are on a mix of VHF and UHF, as well as 800. Maybe those VHF and UHF sites are actually part of someone else's system, the utility paid/licensed them, and they are solely to expand coverage into the plant for those agencies.

Or, maybe it's all a secret plot to confuse Radio Reference users.

 

[Cameron314]

Being a utility, I would guess that there is no call for interoperability or any other 'agency' coming to talk on it. That said, it is conceivable that they have multiband radios and chose to use their licenses on V/U and 8 for one system. Their radios wouldn't care and would just go to the channel that has the grant. No reason it wouldn't work on paper or be any different than any other 7/8 system in the way it handles CHIDs and channel grants.

Now real world, Why do this??? Depending on the location of the subscriber you could have VASTLY different inbound/outbound coverage depending on the band/channel you trunk to. How could you EVER balance out the system repeaters/coverage? If they are indeed doing a single site V/U/7/8 system, this would be an engineering nightmare and I cannot fathom it has ANY advantages to offset the complexity.

I was thinking the same thing that MMcKenna was but I do not see any active CCs being broadcast by this site on V/U yet the SCCs are there.

It's a nuclear power plant so there for sure is a call for interoperability, their NRC operating license will require some form of it. I'm sure that is the reason for it.

 

[DisasterGuy]

I know nothing of the system in question however (at least with a Harris system) this is 100% possible. I’ve actually been looking for VHF and UHF modules and PAs for our shop MASTR V chassis to setup a “just because” site that trunks VHF/UHF/700/800 on a single site into dummy loads.