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

[Marcus Müller]

Hi Meny,

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.

That won't really work, as I explained already[3]. Cell phones of any generation since 2G can (and must) scale their output power depending on link quality, and cellular antennas are far from omnidirectional, so the power density depends on the orientation from the phone. We've discussed this with you [1], and Tom pointed you to these problems of that being a very crude way of measuring distance.

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

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.

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!

We've already discussed this [1][2][3]; I think the right approach here would be to address the concerns that Sylvain, Trip, Tom, Neel, and I had about your way of approaching this.

right now i'm stuck.

Might really be because your approach isn't feasible in its current form.


Best regards,
Marcus

[1] "[USRP-users] Questions about LTE and SDR" from Meny Sidar: http://lists.ettus.com/pipermail/usrp-users_lists.ettus.com/2015-December/017035.html
[2] "[USRP-users] Mobile phones interrogation using the B210" from Meny Sidar: http://lists.ettus.com/pipermail/usrp-users_lists.ettus.com/2015-December/017393.html
[3] "[USRP-users] Measuring distance from usrp to cellular phone with RF power" from Meny Sidar: http://lists.ettus.com/pipermail/usrp-users_lists.ettus.com/2015-December/017154.html

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,

Meny

_______________________________________________
Discuss-gnuradio mailing list
address@hidden
https://lists.gnu.org/mailman/listinfo/discuss-gnuradio