Re: [Discuss-gnuradio] Hi all, how to use usrp and gnuradio support triangulation to locate a cell phone

[Harley Myler]

On May 31, 2010, at 8:49 PM, John Wu wrote:

> hi Harley,
> I think I can bypass establishing communication with the cell phone I want to 
> track, I can use app like airprobe to sniff the cell phone radio. So now the 
> main task is find a good method to locate it. For now there are two methods. 
> First is use three receiver receive the TDOA and use hyperbolic to locate the 
> cell phone. this method need the three receivers synchronize the timer very 
> accurate. the second is use two antenna arrays to use AOA to locate the cell 
> phone, you have mentioned that you have support the antenna arrays in usrp to 
> locate BTS. I want to build my receiver as a handset but if I choose AOA 
> method the distance may be several meters between two antennas in a antenna 
> array. So if it possible to reduce the distance between two antennas in a 
> antenna array and keep the location accuracy? What is the smallest distance?

You are in a different world with a handheld device, my application has the 
array mounted on the belly of an aircraft so my worries are not with the 
antenna since I have lots of room for element spacing. The literature abounds 
with articles on direction finding techniques and what you are hoping to do is 
not out of the ordinary, but I am afraid you are on your own in that regard.

All that I have at this juncture, besides the fact that I have the software 
working on a virtual machine, is the explanation of how the unused GPIO ports 
can be accessed, which is essential for the antenna control that I require. We 
are on break right now, but next week I have some surprises in store for some 
of my unwitting students...perhaps they will post here as the system evolves.

Harley






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