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  #1 (permalink)  
Old 01-24-2018, 12:12 PM
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Default Locate and track the locations of P25 mobile stations

Hello .
I'm working with a Gnuradio program , OP25 trunk -ASTRO25.
How to make Locate and track the locations of P25 mobile stations?
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Old 01-24-2018, 4:50 PM
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Originally Posted by tuthudoznik View Post
Hello .
I'm working with a Gnuradio program , OP25 trunk -ASTRO25.
How to make Locate and track the locations of P25 mobile stations?
You would need to intercept the (proprietary?) gps location responses sent by mobile units on the uplink to the base station. Unfortunately that also means you'd need to be in their general vicinity (close enough to hear their transmissions) as the information is not repeated back out on the control channel.
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Old 01-24-2018, 5:29 PM
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Originally Posted by boatbod View Post
You would need to intercept the (proprietary?) gps location responses sent by mobile units on the uplink to the base station. Unfortunately that also means you'd need to be in their general vicinity (close enough to hear their transmissions) as the information is not repeated back out on the control channel.
It also means you would have to have the ability to tell the radio to send it's GPS data. That is not something your going to be able to do easily. Plus it also means your going to have to key up on the control channel. That's not something you really want to do and get into all sorts of problems over.

This is in the area of Motorola proprietary information and I don't think you want to go there.

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Old 01-24-2018, 6:37 PM
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It also means you would have to have the ability to tell the radio to send it's GPS data. That is not something your going to be able to do easily. Plus it also means your going to have to key up on the control channel. That's not something you really want to do and get into all sorts of problems over.

This is in the area of Motorola proprietary information and I don't think you want to go there.

Jim
Exactly...

Best case you may be able to monitor the occasional location response ISP containing gps info, but practically to derive any benefit you would indeed need to spoof location request OSP messages on the control channel.

There is a white paper about this very topic somewhere out in internet land. It talks about the insecurities of P25 encryption.
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Old 01-25-2018, 12:31 AM
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in which program can the signal be intercepted P25 GPS?
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Old 01-25-2018, 11:24 AM
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in which program can the signal be intercepted P25 GPS?
Most any program that can demodulate and decode a C4FM P25 signal should technically be able to receive the information. (Note: the uplink from mobile device to network equipment is always c4fm modulated regardless of whether the downlink is cqpsk or c4fm).

Note that as mentioned previously, the GPS information exchange is a vendor proprietary extension to P25 and as such good luck finding any documentation on the message formats. In all probability they will be sent as PDUs (duid=12) but whether they are acknowledged or unacknowledged format is unknown.
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Old 01-25-2018, 1:08 PM
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DSD+ program can do it? LRRP.exe ?
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Old 01-25-2018, 7:56 PM
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DSD+ program can do it? LRRP.exe ?
LRRP is for Motorola TRBO not P25.
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Old 01-26-2018, 12:14 AM
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So tell me please in what program you can decode the coordinates of the walkie-talkie P25 ?
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Old 01-26-2018, 7:06 AM
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Quote:
Originally Posted by boatbod View Post
Exactly...

Best case you may be able to monitor the occasional location response ISP containing gps info, but practically to derive any benefit you would indeed need to spoof location request OSP messages on the control channel.

There is a white paper about this very topic somewhere out in internet land. It talks about the insecurities of P25 encryption.
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Originally Posted by boatbod View Post
Most any program that can demodulate and decode a C4FM P25 signal should technically be able to receive the information. (Note: the uplink from mobile device to network equipment is always c4fm modulated regardless of whether the downlink is cqpsk or c4fm).

Note that as mentioned previously, the GPS information exchange is a vendor proprietary extension to P25 and as such good luck finding any documentation on the message formats. In all probability they will be sent as PDUs (duid=12) but whether they are acknowledged or unacknowledged format is unknown.
It depends. Some systems are setup to require all subscribers to send GPS location information if hardware equipped and available.

Also, the data itself is actually defined by the P25 spec though there are vendor proprietary extensions to it.

Currently, I am unaware of any device or software (available to the general public) which is capable to decoding GPS polling info off of P25 though I do believe their are some devices capable of logging the user PTT information including location (sent during PTT).
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Old 01-26-2018, 7:27 AM
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So tell me please in what program you can decode the coordinates of the walkie-talkie P25 ?

I think what they are saying is beyond the legal ramifications of doing this (pretty sure unless you have written permission from whoever is in charge of communications at what ever agency you want to monitor, its definately illegal), its simply not going to be possible with just software, an SDR, and a basic commercial computer. not only shouldn't it be done, but it probably can't be done
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Old 01-26-2018, 11:08 AM
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thanks for the help
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Old 01-26-2018, 1:06 PM
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pretty sure unless you have written permission from whoever is in charge of communications at what ever agency you want to monitor, its definately illegal
Decoding a datastream is illegal?
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Old 01-26-2018, 1:32 PM
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(pretty sure unless you have written permission from whoever is in charge of communications at what ever agency you want to monitor, its definately illegal)
No. Unless you are attempting to circumvent encryption, there's nothing illegal (in the USA) about trying to parse a data packet received over the air. Other nations' laws may vary, what's legal in the USA may not be in Latvia and vice versa.

But you're not going to intercept the GPS packets unless the user is very close, and parsing the GPS coordinates from the data is going to be difficult unless you know the packet format and encoding scheme.

You may get into trouble if you use the data in some manner the police don't like (e.g. posting the locations of officers in real time on a mapping web page), or use the location info to plan or engage in some other illegal act.
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Old 01-26-2018, 2:00 PM
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Default Persistent little so-n-so isn't he...

It would appear this guy isn't concerned with getting himself into trouble. And if he's actually in Latvia it wouldn't matter.
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