NCSHP How to find a car?

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WA4MJF

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I was wondering today how the TCs found a car in rural areas on VIPER where there is
no Simulcast like we have in C-3. Say there is a call for a patrolman in A-2 at night
and TC needs the A-1 overnight car or the EOD/LOD or A-211? They could be in any of the
three counties of the District. Does the TCs terminal tell him/her which tower the car
is connected to? Perhaps the Patrolmen call in when they switch towers? An all call on
all towers in the district? Call on the Troop low band channel and give the info?

Thinking about this today and was wondering.

Thanks,

Ronnie
 

Stephen

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Most agencies have GPS markers in their CAD system that is connected to their MDC (Mobile Data Computer) this allows dispatchers and other units to know their location generally at all times. The MDC's are either connected to the network by internet service provided over an cell service air car or they are using a data stream over a radio frequency of their own for a connection. Additionally, the newest Motorola portables and mobiles for P-25 system do have a GPS function in them as well, but if NC is using Low Band that would not be a function they could use for that particular band.
 

WA4MJF

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Edited to A-2 vice A-1 in second sentence.

I was wondering today how the TCs found a car in rural areas on VIPER where there is
no Simulcast like we have in C-3. Say there is a call for a patrolman in A-2 at night
and TC needs the A-2 overnight car or the EOD/LOD or A-211? They could be in any of the
three counties of the District. Does the TCs terminal tell him/her which tower the car
is connected to? Perhaps the Patrolmen call in when they switch towers? An all call on
all towers in the district? Call on the Troop low band channel and give the info?

Thinking about this today and was wondering.

Thanks,

Ronnie
 

mhodgson

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Raleigh, NC
Ronnie, the system broadcasts to any site where there is a radio on a particular talk group affiliated. If Raleigh Radio calls an A1 car, then any site that has a radio affiliated to "A1" will receive the message...thats how the Motorola trunked systems operate in multicast...if there is a radio affiliated at a particular site on a particular talk group, then the system sends traffic on said talk group to said site.

M
 

milf

Careful, I CAN hear you!
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As they upgrade to full P25, the new radios do indeed have much better AVL/GPS functions built in. As long as an radio can hit and affiliate with an site, if those functions are enabled, you know where that radio is. This is also how agencies find stolen radios. You can remote monitor, locate, or kill any mobile/ht on the system on the ASTRO-25 (ASTRO 7.1X) platform.
 
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KE4ZNR

KE4ZNR@radioreference.com
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As they upgrade to full P25, the new radios do indeed have much better AVL/GPS functions built in. As long as an radio can hit and affiliate with an site, if those functions are enabled, you know where that radio is. This is also how agencies find stolen radios. You can remote monitor, locate, or kill any mobile/ht on the system on the ASTRO-25 (ASTRO 7.1X) platform.
True to an extent. In the Moto line of radios an XTS radio requires an external
add on (usually through the RSM lapel mic) to have AVL/GPS capability whereas the APX line comes with that capability
"built in" to the radio (but not turned on in the system). Like anything else Moto you gotta pay extra to have the added "goodies" turned on. :D

Here in Durham the city PD decided a few years ago to go with the "Trimble Placer Gold" AVL units that look like this:


Overall they have withstood alot of abuse and we have very few issues with the Trimble Units.

Like anything else in communications what one agency does is usually quite different than neighboring agencies.

Marshall KE4ZNR
 

mhodgson

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The over the air GPS capability that P25 affords is a good concept, but one that has to be taken into consideration very carefully, especially in a large system (more geographically, than number of users). Marshall is correct that the older XTS/XTL units do not have a built in GPS capability however the APX series does. I know of a large, metropolitan city that elected to turn the feature on in their system of ~10K radios and set the update time for, if memory serves me right, five minutes. This means that every five minutes the radios are returning a GPS coordinate to the central controller....needless to say it didnt take a rocket scientist to figure out the consumption of bandwidth/overhead and the correlation to system busies, etc. before there was a wholesale rethink of the concept. They now update when powered on or off, and I think....hourly...however they can be "polled" if need be to determine where they happen to be.

M
 

KE4ZNR

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Raleigh, NC
The over the air GPS capability that P25 affords is a good concept, but one that has to be taken into consideration very carefully, especially in a large system (more geographically, than number of users). Marshall is correct that the older XTS/XTL units do not have a built in GPS capability however the APX series does. I know of a large, metropolitan city that elected to turn the feature on in their system of ~10K radios and set the update time for, if memory serves me right, five minutes. This means that every five minutes the radios are returning a GPS coordinate to the central controller....needless to say it didnt take a rocket scientist to figure out the consumption of bandwidth/overhead and the correlation to system busies, etc. before there was a wholesale rethink of the concept. They now update when powered on or off, and I think....hourly...however they can be "polled" if need be to determine where they happen to be.

M
Mikes excellent example above is exactly one of the many reasons our city PD decided to go with a separate AVL solution vs one built into the radio system.
Cost is always the bigge$t factor :) but radio system abilities also play into it. Our radio system is on a migration path to 7.13 but is currently still at 4.1 platform. The majority of our public safety users still use the XTS/XTL platform of radios with the XTS 5000 being still the "top dog". It was decided years ago that it was cheaper to use the Trimble solution instead of equipping all radios plus upgrading our radio system at the time to handle AVL.
Now if an officers AVL Trimble box goes south it is a simple Trimble box swap or a serial cable swap and he is back in service.
Marshall KE4ZNR
 
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ts548

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We use standard USB GPS that coexists with our MDIS program. Sends everything via the VZPN back to the CAD system.
 

jthorpe

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Most agencies have GPS markers in their CAD system that is connected to their MDC (Mobile Data Computer) this allows dispatchers and other units to know their location generally at all times. The MDC's are either connected to the network by internet service provided over an cell service air car or they are using a data stream over a radio frequency of their own for a connection. Additionally, the newest Motorola portables and mobiles for P-25 system do have a GPS function in them as well, but if NC is using Low Band that would not be a function they could use for that particular band.
I understand you're not talking about NCSHP specifically but just to be clear, we don't have AVL.
 
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