Looking for any materials about GSM detection

[Shaggy]

GSM detection

Hello

Can someone please give me some pointers on mobile phone detection? I'm looking for some text files or whatever which explains how these thingies work. Circuit designs are welcome as well.

Many thanks.

Shaggy

 

[hot_chmock]

Hi shaggy,

I'm interested too in this subject, I already check on the net and could find a few commercial products.

I think this can be detected on different ways, maybe a "mobile phone guru" can help.

I was looking for a system that can detect it at about 50 m without transmission.

hc
:wink:

 

[shanren]

these products are popular in china,taiwan,and it is very cheap,about 1$ or so.it have a asic chip,which i can not see it is name.but i hear it is made in taiwan.this things make for women,who put their mobile in bags,sometimes can not hear the ringer.the little things are tied in bags,when there is a phone call,it can detect it,and will twinkle the led,and beep.it need no connector with the mobile phone,use a small battary,only a thumb size.but this things can not be 50m far away from your mobile,it can not work so far away.
you can search taiwan elec company for some info.
thx.

 

[Shaggy]

Thanks shanren.

I know those litlle devices. Very often they are made of a single coil or a small led or whatever with a particular gas in it that gets ionised and it lights up.

I was more looking for some serious hardware which can detect mobiles even when they are not transmitting. They are out there but to me it's like a big black box and I think those devices have become quite complex.

Appreciate it shanren.

Rgds
Shaggy

 

[goxy]

That device is very complex and illegal , cost about 10k$.
And have possibility scaning all gsm band.

 

[Shaggy]

Illegal? Over the past few weeks I've seen sincere companies selling them (from what I saw on their website).

I'm not talking about those circuits which block any cell phone signal. I can imagine those are illegal but not the ones which only detect them.

As you might know, cell phones are prohibited at intensive care units, chemical plants, you name it. So I can't think of any reason why they are illegal.

Kind regards
Shaggy

 

[goxy]

You are not good specified what you want.
You need small black box, not big.
If you want just detect phone not phone detection you must detect signal with receiver on phone band (880-915 Mhz).
You can do that with LO on 900Mhz ,900Mhz mixer with IF on 25Mhz and simple 25Mhz detector.
****This principles is for long distances and you must have transmitter on base station band from 935 to 960Mhz (similar like receiver ,just detector replace with generator pseudo random numbers with 50Mhz bit speed).
This is trick because you must kill base station signal and than phone will start to find new free channel.
If you want device without transmitter ,I think that is only solution detect LO in phone receiver but this is for very short distances.

 

[elecing]

Re: GSM detection

USEFUL FILE.