Troopers working in King George are occasionally heard on the main sheriff's frequency. However, given that the sheriff's frequency is VHF P25 and the STARS system is VHF P25, I would guess that the troopers' radios are simply programmed with the King George frequency rather than getting a separate VHF radio.
sometimes VSP is heard talking to Appomattox County Dispatch and Prince Edward County dispatch and one of the troopers i talk too who used to live in my area had a second radio in his cruiser to talk to the County which is the SIRS channel, it's a separate channel, here's the link for you Virginia - Common/Shared Scanner Frequencies and Radio Frequency Reference not sure if i'm allowed to post links but i hope that helps you, i was confused too lol when i first started listening to VSP, also if you live in the NKC/CC area you would hear a unit come up on the County dispatch before they encrypted the channels in NKC not sure about CC, i could be wrong but i think all the troopers working the rural areas except the Area 32/46/47 units would have the second radio in the car as well
Pittsylvania has issued troopers portable radios for their Harris system but you cannot hear them because they stay encrypted, (then ask for the public's help whenever they cant solve a crime, LOL) and you will also hear trooper's on Craig, Patrick, Franklin (another encrypted law agency), and the Bedford systems. I know a few trooper's who bought their own radios for analog systems, but counties that have TRS typically loan/assign VSP radios. Some even have a secret squirrel channel or two. SIRS is still around, but in central Virginia the only local agency I ever hear is Campbell County usually talking to VSP units. Some localities have cross band repeaters and some have talkgroups for SIRS, so if you hear the term SIRS repeater thats generally what they are referring to, some agencies totally removed an actual SIRS radio from vehicles and took these steps for communications. There is NO low band repeaters except for those used by VDOT, and BTW SIRS is channel 50 in the VDOT lowband radios, recieve only. Lastly, VSP dispatchers have SIRS on their consoles as some STARS sites have a SIRS access, not all sites, but some.
The same as a crossband repeater for a vehicle where the user has a higher wattage mobile in vhf and uses a UHF or 700/800 portable when away from the vehicle. The VRS ( Vehicle Repeater System) is connected to the high power unit in the vehicle. When the VRS receives traffic from the portable ( handheld) it signals the high power mobile unit to transmit that same traffic. Its a good system to use where portable radios have limited range due to terrain.
An agency has a SIRS radio that receives the audio and it's rebroadcast over their system on a specific frequency or talkgroup. In turn, the agencies system will then send its audio back to the SIRS radio to be transmitted through it.
It's alot more complicated than that. That's just as simple as I can explain it.
A sirs link is just what it says. Its a link to connect a control point to a control station remotely. typically these are low power links to get a siganl from say dispatch to the top of a mountain for better coverage. Mostly they have directional antennas so I don't know how much you can hear on them. Its Sirs. Its mostly just noise around where I am at. Its usage has really dropped off over the years.
I feel confident in saying some dispatchers have relabeled SIRS on their console to "MUTE," lol.
Why would they remove the radio? Alot of local agencies have removed their SIRS radios since they have the newer "links" or talkgroups, conserves space in the vehicle and one less antenna. However, VSP, DGIF, DOC, and the like still have SIRS mobiles, usually a Motorola CDM750, mainly due to interoperability requirements for grants, but/and its there just in case. If you have an older scanner just sitting around, you can put it to use like I did with an older BC-996T, mine is dedicated to interop monitoring with SIRS and even the old favorite 39.50, and everyone once in awhile it actually hears traffic. Personally I think the SIRS board (if they still have that around) should consider a move up to highband, like 155.475, 155.370, or even 154.665.
Fairfax County uses patch Talk groups for County PD to listen and Troopers can talk on all Fairfax County/City talk groups if necessary. I believe Fairfax County k-9 and helo will talk directly with VSP on their own channels. Fairfax County is using triband radios.