MARCS vehicle locators...how is this transmitted to CAD? via data channel?

[dizwiz]

Its my understanding CAD (computer aided dispatch) is supposed to have up a screen that shows them where their units are.

Does this work in real time?

How does it work? Is there a continuous signal being transmitted from the unit to the tower, via a MARCS data channel, to the CAD center?

Or is the signal intermittent (example, the MARCS subscriber pushes a button that sends his/her location info when he/she feels like it. )?

 

[TrenchFeeder]

I would assume GPS. If you look at most police interceptors you will notice a small flat circle on either the roof, or the trunk lid. It's a GPS antenna. It's not a hard thing to do to track somebody in real time via GPS. I have that capability on my phone, it works on any other phone I know the number to, that has GPS capabilities.

Some departments do not have this technology as I regularly hear dispatch saying "Whats your 20?" . However I am merely speculating and not saying this based on any facts, simply an educated guess

 

[Q101ATFD]

I would assume GPS. If you look at most police interceptors you will notice a small flat circle on either the roof, or the trunk lid. It's a GPS antenna. It's not a hard thing to do to track somebody in real time via GPS. I have that capability on my phone, it works on any other phone I know the number to, that has GPS capabilities.

Some departments do not have this technology as I regularly hear dispatch saying "Whats your 20?" . However I am merely speculating and not saying this based on any facts, simply an educated guess

You have not offered any insight to the original question - it's assumed that GPS provides the location of the cruiser, but the question posed is: how is the GPS location transmitted back to the communications center?



More than likely, there is one or more data talkgroup (trunked), or channel (conventional) that provides this capability. It's generally the same data channel that is used to send information to and from the MDC. The position is updated anywhere from every 5 seconds to one minute - depending on home many units there are, and how many data channels there are.

 

[datainmotion]

Typically GPS/AVL data is packetized with the other CAD data going back and forth. This is done by the mobile client regardless of what medium is used (cellular or LMR)

 

[dizwiz]

my question is how is this data transmitted back to the tower (to MARCS).

I imagine it goes along with MDT data back to the tower.

Is it through a conventional data channel ? (there is a list of them (all in the 800 MHz range), associated with MARCS, its not in this websites database though)

or is there some 'digital' talkgroup that this is being transmitted on?
in that case I would assume the input frequency could be any of the input frequencies usually associated with that tower.

 

[ctpd845]

All the MDT data is transmitted using the MARCS DataNet, which you can find in the database under Ohio state agencies.