Understanding STARS

[Chris45]

Hello All,

There are a couple of aspects about STARS I would like to understand better. I am located within Division 7 and pick up traffic from the local sites with no problems. My fist question is how would a VSP unit in Division 7 communicate using STARS in another Division? Do they simply switch channels on their radio and talk direct, or do they use one of the several interoperability channels in the STARS system? Would this sort of transmission be one that could be heard with only Division sites, or would you need to program all STARS sites and hope for an interception. Really appreciate knowing how that works, any many thanks in advance.

 

[tglendye]

I don’t know department protocol so my answer may be incorrect, but as I understand it the trooper would simply switch channels in most circumstances. It seems the interop channels are basically used between different state agencies (ie DGIF and VSP) or between state and local governments. This is just my interpretation, however.

In the example you gave, the transmission should be heard on the tower’s control channel you normally hear the unit on. There are talk groups you can miss due to no unit currently being affiliated with the tower you are monitoring. If a user (trooper for example) is not affiliated with a the tower, there is no need to send traffic across that particular tower site. I have a GRE and RadioShack scanner... sometimes I am scanning 3 towers in different scanlists so I will have a better chance of not missing any TG’s I would like to monitor.

I am sure I over simplified the issue or maybe even got it completely wrong.

 

[QDP2012]

Tower-affiliation:

• In general, (unless a TAC channel is used,) VSP units that want to talk directly to another VSP unit must request permission from the dispatcher for a "mobile-relay", which the dispatcher enables. The towers that are involved in a given transmit/receive session are the towers with which the field units are affiliated at that moment.
  
• So, if a Richmond VSP car travels to Roanoke, but stays on a Richmond talkgroup, the tower in Roanoke will be active on that talkgroup and you will hear that traffic on the Roanoke tower's frequencies.
  
• If a Roanoke car wants to talk to a Fairfax car, but both are in their home districts on their home talkgroups, then the dispatcher would need to set-up a relay (unless they go to a TAC channel).
  
• If the SmartTraffic safety-truck on I-64 is talking to the truck on I-81, the towers nearest each truck will be active. You will be able to hear the traffic if you are able to receive one of the tower's signals.

Programming Scanners

• If you are normally stationary in your hometown, and are not regularly traveling the state (as part of your job or something), then you will only benefit from programming into your scanner, the towers which you can locally receive (given your antenna placement and signal strength, etc.).
  
• Having said that, sometimes you will be able to hear towers from other divisions. (From Division 3, I have heard Fairfax doing traffic stops on its local interstate. Sometimes I can hear Richmond in Division 1.)
  
• In my Pro106, I created a separate TSYS for each division, so that when I travel I can lockout the TSYS(s) that I don't want to hear and the scanner won't waste time scanning them. For me, this works better than putting the entire STARS system into one TSYS. I also created a separate TSYS for the STARS tower nearest my home, so that I don't have to unnecessarily scan the other towers in my home division.

A STARS expert can probably give a more detailed answer of how radio-traffic is processed.


EDIT: You can program the other divisions' talkgroups into your scanner but only program the frequencies for your receivable-towers. This way, if another division's car wanders into your division, you can hear their traffic. -- Just a thought.

Hope this helps,

 

[QDP2012]

I am sure I over simplified the issue or maybe even got it completely wrong.

Sounds right to me.

 

[Chris45]

Thank all of you for the information that was provided. It has helped to clarify my understanding of the system.

 

[John]

All of this information is technically correct, but a few minor corrections. There is no need for a dispatcher or anyone to enable the 'mobile relay'. It automatically happens UNLESS there is some policy in place to prevent it. I understand that VSP has such a policy to prevent units traveling across the state and using their home channels in some other area. This is to avoid overloading the limited number of RF channels available at each site. I am not sure the dispatchers can even enable this if it is requested. I think they prefer the units to use the local divisions channels again to avoid overload.

However some other agencies don't have this limitation. So some channels in other agencies are truly statewide. If a unit on a tower in far SW VA wants to talk to a unit on the eastern shore they can with no need for anyone else to be involved. Their transmission would be heard on any tower in the state that had a unit affiliated with that tower with that channel selected. If no unit on that channel is in a tower area then that tower doesn't transmit the signal.

STATE-1 is a statewide talkgroup that is not limited or does not require intervention to be used to talk to someone somewhere else.

I hope this makes sense. From a scanner perspective the explanation answers your basic question. Program in your local tower frequencies and any talkgroup you would be interested in hearing no matter where it is normally used.

Tower-affiliation:

• In general, (unless a TAC channel is used,) VSP units that want to talk directly to another VSP unit must request permission from the dispatcher for a "mobile-relay", which the dispatcher enables. The towers that are involved in a given transmit/receive session are the towers with which the field units are affiliated at that moment.
  
• So, if a Richmond VSP car travels to Roanoke, but stays on a Richmond talkgroup, the tower in Roanoke will be active on that talkgroup and you will hear that traffic on the Roanoke tower's frequencies.
  
• If a Roanoke car wants to talk to a Fairfax car, but both are in their home districts on their home talkgroups, then the dispatcher would need to set-up a relay (unless they go to a TAC channel).
  
• If the SmartTraffic safety-truck on I-64 is talking to the truck on I-81, the towers nearest each truck will be active. You will be able to hear the traffic if you are able to receive one of the tower's signals.

Programming Scanners

• If you are normally stationary in your hometown, and are not regularly traveling the state (as part of your job or something), then you will only benefit from programming into your scanner, the towers which you can locally receive (given your antenna placement and signal strength, etc.).
  
• Having said that, sometimes you will be able to hear towers from other divisions. (From Division 3, I have heard Fairfax doing traffic stops on its local interstate. Sometimes I can hear Richmond in Division 1.)
  
• In my Pro106, I created a separate TSYS for each division, so that when I travel I can lockout the TSYS(s) that I don't want to hear and the scanner won't waste time scanning them. For me, this works better than putting the entire STARS system into one TSYS. I also created a separate TSYS for the STARS tower nearest my home, so that I don't have to unnecessarily scan the other towers in my home division.

A STARS expert can probably give a more detailed answer of how radio-traffic is processed.


EDIT: You can program the other divisions' talkgroups into your scanner but only program the frequencies for your receivable-towers. This way, if another division's car wanders into your division, you can hear their traffic. -- Just a thought.

Hope this helps,