GSM signals Detection

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Adil Israr

Joined: 05 Sep 2008
Posts: 72
Helped: 1

07 Apr 2009 18:45 mobile call detectors as a project

Hi,,
I have a question about GSM signals,that when we make or receive calls what kind of signals are there and can we detect these signals??

Communications_Engineer

Joined: 10 Oct 2008
Posts: 492
Helped: 39

08 Apr 2009 5:25 how to detect gsm signals

signals are analog and sure, why wont we be able to detect those signals. demodulation and reception of data in those signals may be difficult though

pranam77

Joined: 22 Apr 2008
Posts: 1071
Helped: 94
Location: Mangalore(India)

08 Apr 2009 9:49 detect gsm location

Adil Israr. This kit available from "www.united77.com/projects.htm" will do exactly what you want. Mobile detector bug/ Cell tracker detects the transmission of any cellular phone operating in the ultra high frequency range in 1.5 meters of its radius. This battery operated gadget is highly helpful in classrooms and examination centers to prevent malpractices. Number of ICs used: 2

Adil Israr

Joined: 05 Sep 2008
Posts: 72
Helped: 1

08 Apr 2009 18:56 detect mobile signals

But I am not able to download those,,if u have downloaded so plz attach one.
I donot want to demodulate these signals but just to detect them when mobile is active.Is it possible??

pranam77

Joined: 22 Apr 2008
Posts: 1071
Helped: 94
Location: Mangalore(India)

09 Apr 2009 6:49 detecting gsm signals and phones

Hai Adil. The site i have given is one who maufactures the kits. No schematics are available on thier site. You'll get all the details regarding the project (Schematics, Component layout of the PCB, description of the project) when you buy the kit. Yes the said kit detect the signals of any mobile in a range of 1.5 - 2 meters. It sounds a buzzer in an event when a call is made or a call is received, a message is sent or any message is bieng received. Good luck.

Adil Israr

Joined: 05 Sep 2008
Posts: 72
Helped: 1

12 Apr 2009 18:44 rf detector project gsm

Ya I need the same one,,but i do not know the sinals it detects what kind of are they??Because mobile signals We get all the time,24Hrs??Plz if you can help, help me in this regard. I shall be thankful to you.
Bye & thanks for reply.I hope you will help me.

pranam77

Joined: 22 Apr 2008
Posts: 1071
Helped: 94
Location: Mangalore(India)

13 Apr 2009 8:31 Re: GSM signals Detection

Adil Israr wrote:

Hai Adil...You are right...we get mobile signals 24 hours... As the sensitivity of this circuit is limited, it detects only those signals which are available in a radius of 1.5- 2meters from its antenna. Hopefully from a mobile in your or your friends pocket...Helpd?....Dont forget to press the Helped me button at the bottom. Goodluck

Adil Israr

Joined: 05 Sep 2008
Posts: 72
Helped: 1

13 Apr 2009 18:58 Re: GSM signals Detection

Ya certainly you helped,,,,this device only detects signals of active mobile within its radius,that mobile always get other signals 24Hrs,it means its buzzer always sounds.Then what are those signals which it detects when mobile is active??
you certainly have noticed that when mobile set is near any audio player,,and it receives call we usually hear signals in speakers??What are those signals??Is there any relation between these siganls and signals detected by the device you mentioned??

Thanks again for your helpful reply.

FvM

Joined: 22 Jan 2008
Posts: 5154
Helped: 766
Location: Bochum, Germany

13 Apr 2009 19:22 GSM signals Detection

GSM is using time divison multiplex and thus transmitting in bursts with about 210 Hz repetition frequency. The RF burst is present during a call, when registering or unregistering to a network and occasionally in registered state. The said audio inferences are caused by the demodulated RF burst. The RF is also easily detectable in the mobile's vicinity by simple passive circuits and can e.g. light a LED without a battery.

Adil Israr

Joined: 05 Sep 2008
Posts: 72
Helped: 1

13 Apr 2009 19:38 Re: GSM signals Detection

FvM will you plz elobrate your point or give me any document that can help me thanks.

pranam77

Joined: 22 Apr 2008
Posts: 1071
Helped: 94
Location: Mangalore(India)

14 Apr 2009 8:34 Re: GSM signals Detection

Adil Israr wrote:

The phone may be "receiving" the signals 24 hours. This doesn't mean the buzzer sounds 24 hours. Coz the circuit is a basically a RF detector which detects the transmission of mobile phones and not a receiver. It will detect only the mobile when the mobile transmits and not when receives. The mobile when receives any valid call or SMS, it will also transmit back to validate the same and this signal is detected by the circuit. The same signal is what you recieve on the radio or any other audio equipment as an interference.

Adil Israr

Joined: 05 Sep 2008
Posts: 72
Helped: 1

14 Apr 2009 19:39 Re: GSM signals Detection

Can you provide me any related document or web??Thanks

pranam77

Joined: 22 Apr 2008
Posts: 1071
Helped: 94
Location: Mangalore(India)

15 Apr 2009 8:00 GSM signals Detection

Hai Adil,
As they sell only kits, no schematics are available. A brief description of the same is available on thier website www.united77.com/projects.htm....Good luck