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Re: [Discuss-gnuradio] Picking up RF cellular signals

From: Ralph A. Schmid, dk5ras
Subject: Re: [Discuss-gnuradio] Picking up RF cellular signals
Date: Tue, 15 Mar 2016 15:26:45 +0100

The phones will register to your base station, when there is no infrastructure any more - this is a common scenario in a real disaster, the cell phone infrastructure will collapse quite soon. In this situation all surviving phones will search for a new signal, find your BTS and register. Then you can find out the TA values and try locating then.


In fact exactly this is done when people get lost out in the woods, or in the mountains - putting a GSM cell on board a helicopter...



From: address@hidden [mailto:address@hidden On Behalf Of Meny Sidar
Sent: Tuesday, March 15, 2016 3:18 PM
To: Nikos Balkanas
Cc: address@hidden; Marcus Müller
Subject: Re: [Discuss-gnuradio] Picking up RF cellular signals


Thank you for your comments.

Marcus, sorry for bugging you with this issue.

I am well aware of the previous discussions with you, and have learned from them as well as from other people.

however, when i come across something like this for example:

i keep thinking that there is some kind of heat signature in the spectrum that the cellular produces (please correct me if im wrong)

how else can you explain this works?


I know my approch is not ideal, and i'm not ruling out opening a bts base station,

but i cant find a way to make phones register to my station automatically..


thanks again for your comments guys,

really appreciate it.




2016-03-15 4:11 GMT+02:00 Nikos Balkanas <address@hidden>:

Indeed, there is phone locator protocol, and a service offered as by some companies. They work through provider contracts. The problem is that you have to know the phone number beforehand and the carrier. Not very useful in a disaster case :(





On Mon, Mar 14, 2016 at 5:50 PM, Marcus Müller <address@hidden> wrote:

    True, at least unless you send them something they have to react to. Which the phone will only do if you're the infrastructure, and usually implies you authenticate as such[2]. Which will hence most likely only work if the cellular providers cooperate with you.


On 03/14/2016 03:54 PM, Meny Sidar wrote:

Hi guys,


I am currently working on a project for my university, where i'm trying to locate cellular phones using SDR (USRP B210).

The idea of the project is to be able to find survivors/victims in disaster areas, such as earthquakes, by assuming they have their cellular on them.


What i did so far, is a program that calculates and outputs in a loop the power transmitted from a cellular phone from it's uplink channel. that can tell me my distance to it.

problem is, that cellular phones are usually in idle mode and not transmitting at all. 

So it works, but only if the phone is currently transmitting to the network (phone call, internet, etc..)


I'm trying to find a solution for this,

There has to be a way of knowing that some kind of RF transmitter/receiver is near me...

If anyone can shed some light on this subject, what can i do or if i need to go in another way, i'll be very grateful! 

right now i'm stuck.


Thanks a lot,



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