[op25-dev] Project question

Matt Ames matt.ames7bc@gmail.com [op25-dev] op25-dev at yahoogroups.com
Thu Sep 22 01:30:52 UTC 2016

Hi Alex,

Some of those ideas/tasks date back to 2008 when the project was its'
initial embryonic stages. The idea back then was to find a way to track a
P25 station geographically - for example, using multiple time and frequency
sync'd USRP's (with GPSDO for location and time sync) to do time difference
of arrival type location determination, or even a Roanoke Doppler style of

Since then, Motorola TRBO and DMR has become very popular, and with it,
services such as LRRP are transmitting data over some of these networks. I
know that some of the Motorola APX and TRBO series radios can be set up to
transmit their GPS locations in the clear, which could be easily read over
the air. This has been done in other projects with TRBO, but not with P25
to my knowledge.

These are just a few ideas I threw around, Balint (with some assistance
from me) implemented a great SDR Doppler RDF. It wasn't tuned for P25 but
it did work well on whatever it was tuned to.. Balint since went to
California and worked on another setup using a USRP and an algorithm called
MUSIC that worked very well...

In short, there are many ways of determining the direction an RF signal is
coming from, and then using this to triangulate a position..


On 22 September 2016 at 02:48, Alex alex323 at gmail.com [op25-dev] <
op25-dev at yahoogroups.com> wrote:

> Hi. On the front page of the wiki (http://op25.osmocom.org/trac/wiki) I
> see the following bullet point:
> "Locate and track the locations of P25 mobile stations."
> What exactly is meant by this? How could such a thing be accomplished?
> --
> Alex
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