Roanoke Public Safety System

[musicman]

Today, I am hearing new frequencies in use in conjunction with the Roanoke City/County trunked radio system. City Police 1 is being retransmitted on 866.5125. City Fire/EMS is on 867.5125. I am getting hits on the input frequencies, but I can't tell yet if they are from mobiles.

The callsign is WPMJ304. This is supposed to be a 5-channel conventional (non-trunked) public safety assignment.

 

[RFEMSG1]

City Trunked System

Earlier this morning the 800 City System went out ,why I don't know right now but they were using Tac Channels called M/A 1,2,3,4. Don't know if those are National Mutual aid channels or what was going on. But it only affected the city and not the county

 

[John]

The GPS receiver that keeps Mill Mountain and the other sites synchronized failed so the transmitters were all coming up on slightly different frequencies and it was very difficult to understand any transmission. (Hetrodyning). Normally these different sites transmit simultaneously to provide better coverage but they must be on EXACTLY the same frequency to avoid this problem.

The city went to the ITAC channels (they call them Mutual Aid T1 and T2 for PD and T3 and T4 for Fire/EMS). These are conventional repeaters and are programmed into all the city radios. These are the nationwide mutual aid channels recommended by APCO and NPSPAC.

The county basically continued to operate through the interference though they did do some talking on their conventional channels also (Poor Mtn, Ft Lewis, etc).

This impacted the city a little more than the county since the city also uses the 800 trunk system to activate their Fire/EMS stations using MOSCAD. If they can't talk on the trunk system then they have to manually ringdown the stations. The county still uses low band paging for this function.

The city mobile data terminals were not affected since they are independent of the trunking system.

Once the Mill Mountain site was turned off everyone was able to switch back to the trunking system. This took about 1-1/2 hours. Mill Mountin is still off so coverage is poor in some places.

 

[musicman]

Roanoke Mutual Aid Channels

John:

Thank you for the very informative post. I did not appreciate that all the repeaters were transmitting at once. Imagine the precision and stability required to avoid the heterodyning (I heard it, too).

A couple of questions:

-What is Roanoke's designation for the "calling channel" (866.0125 output)?
-Does Roanoke County not use these channels, and does the City avoid use of the "talkaround" channels on Poor, Tinker, Lewis, and Crowells? I believe that I have heard city fire units at the jail using 854.9875 (Tac 16).

 

[John]

Hopefully the following will help explain some of this a little better.

Standard name & freq (out/in) = Roanoke City name
ITAC Call 866.0125/821.0125 = NAT CALL
ITAC-1 866.5125/821.5125 = MUT TAC 1 primarily for PD
ITAC-2 867.0125/822.0125 = MUT TAC 2 " " "
ITAC-3 867.5125/822.5125 = MUT TAC 3 primarily for FD
ITAC-4 868.0125/823.0125 = MUT TAC 4 " " "

These ITAC channels are also used in the Bedford (EDACS) system and they have discussed having some Roanoke Co EMS (Vinton) units using them when they respond mutual aid in that area. I believe they are also used in the Richmond and DC areas. It is recommended that all Public Safety 800 MHz radio systems monitor the calling channel so other 800 users can call for help if needed when out of their primary system area. Roanoke City does try to monitor the calling channel just like they try to monitor SIRS and the MED channels. I don't know if the county also monitors them or has them programmed into all their radios.

I do know the repeaters on these freqs are licensed to Roanoke City and I believe they are located on the courthouse downtown.

As far as the conventional repeaters on Poor Mtn, Ft Lewis, Crowells Gap and Tinker. I know the city has these frequencies (and talkarounds) programmed into their radios. However, I haven't really heard them use them. I have heard the county use them but primarily when they are having trouble accessing the trunk system in outlying areas. I also don't think the county has talkaround programmed in for their radios except for the Poor Mtn freq (854.9875).

As far as the City TAC-16 channel, I am not sure what it is. I have never been in a position to receive it. However, based on some experimentation I do not believe it is 854.9875 (Poor Mtn talkaround). I am not sure what freq it is.

Maybe someone else can help us figure this one out.

John