CrazyEngineers Archive
Old, but evergreen and popular discussions on CrazyEngineers, presented to you in read-only mode.
@silverscorpion • 05 Jul, 2009
Hi guys,
It's time for a mini project in communications, and I've thought about a cell phone Jammer. Short range, of course.

Now, I want you guys to chip in some ideas about how to go about this.

Basically, I know that cell phones operate in the 800 - 1800 MHz band. And to jam the cell phones, we have to create a random noise at the same frequency with more power. This much I know.

Now, the doubt is, how to find on which particular frequency the phone is currently operating. I guess we cant do that, so we have to sweep the entire frequency range continuously. How fast should I do it? ie, how fast should the frequency sweep from the lower end to the higher end?

Ideas please.. Help in circuit level implementation is also welcome!! 😀😀
@Harshad Italiya • 06 Jul, 2009 Hey Nice Concept Scorpion i am interested in this project.. let do it together.
@cranky • 06 Jul, 2009 Hey, nice start.are you going to jam the signals or block them.Isn't jamming illegal😁

And one more thing:are we going to jam a single frequency(assuming speaking and listening signals are at same frequency)or two frequencies😕
@fake_lover01 • 06 Jul, 2009 I think this project was also done by some of my classmates
@silverscorpion • 06 Jul, 2009
godfather
Hey Nice Concept Scorpion i am interested in this project.. let do it together.
That's great. I could use a partner..

Do you have any prior experience in communications side??
Just so that it'll be useful to us. Anyhow, I look forward to your help in this.. 😀
@silverscorpion • 06 Jul, 2009
cranky
Hey, nice start.are you going to jam the signals or block them.Isn't jamming illegal😁

And one more thing:are we going to jam a single frequency(assuming speaking and listening signals are at same frequency)or two frequencies😕
Yeah, I think it's illegal, but I guess it's ok for a simple college project. Also, I'm not trying to jam a big area. Just some 7-8 ft distance is enough. So, I guess it wont be a problem.

And about single frequency or double frequencies, a cell phone uses two frequencies in every call. One for talking and the other for listening. If we are to block these two frequencies, we have to first identify which frequency the phone is operating in. That is difficult. So, I think I'll just put some random signal in the whole spectrum used by cell phones, ie, from 800 MHz to 1.8 GHz. That's the idea right now. I dunno how I'm gonna do it, though..
@silverscorpion • 06 Jul, 2009
fake_lover01
I think this project was also done by some of my classmates
It'd be great if you could get them here, to share something about this project.

I'm sure they'll love CE too.
Wait, are they here now?? If not, invite them!!😁
@cranky • 06 Jul, 2009
silverscorpion
Yeah, I think it's illegal, but I guess it's ok for a simple college project. Also, I'm not trying to jam a big area. Just some 7-8 ft distance is enough. So, I guess it wont be a problem.

And about single frequency or double frequencies, a cell phone uses two frequencies in every call. One for talking and the other for listening. If we are to block these two frequencies, we have to first identify which frequency the phone is operating in. That is difficult. So, I think I'll just put some random signal in the whole spectrum used by cell phones, ie, from 800 MHz to 1.8 GHz. That's the idea right now. I dunno how I'm gonna do it, though..
Oh..i didn't know that😒..will be interested in how you go about it..
@Harshad Italiya • 06 Jul, 2009
silverscorpion
That's great. I could use a partner..

Do you have any prior experience in communications side??
Just so that it'll be useful to us. Anyhow, I look forward to your help in this.. 😀
I dont have but i am sure we will do this!!
give me sometime i am searching for something which will be helpful to us. 😁
@shalini_goel14 • 06 Jul, 2009 Hey fellas,

Why you people are using your awesome brains in making stuff that would be of no help to anyone ever? Isn't it possible for you to make something useful ?

I guess make a mobile charger for mobile phones(or laptops) that do not work on electricity 😛 I can then buy your idea ? Do these frequencies and signals do not provide any kind of energy ? 😕
@Anil Jain • 06 Jul, 2009 • 1 like
shalini_goel14
Hey fellas,

Why you people are using your awesome brains in making stuff that would be of no help to anyone ever? Isn't it possible for you to make something useful ?
It is Useful Shalini.

Was just thinking, terrorist use their cellphones on borders. If We will have 'Cell phone Jammers' which can identify their specific phone frequency, we can jam them.

Am I sounding a bit alien???

-CB
@Harshad Italiya • 07 Jul, 2009 @ SilverScorpion... i think we have to make a Circuit which make a Noise of particular Frequency which will be superimpose on the mobile frequency range.
@Harshad Italiya • 07 Jul, 2009
crazyboy
It is Useful Shalini.

Was just thinking, terrorist use their cellphones on borders. If We will have 'Cell phone Jammers' which can identify their specific phone frequency, we can jam them.

Am I sounding a bit alien???

-CB
Yes CB that's the reason why we need to make such devices.
@Harshad Italiya • 07 Jul, 2009 @SS
CDMA and GSM have different frequencies so we have to generate that frequencies with more power how if we make two different transmitters which generate the frequecy of CDMA and GSM.
@shalini_goel14 • 07 Jul, 2009
crazyboy
It is Useful Shalini.

Was just thinking, terrorist use their cellphones on borders. If We will have 'Cell phone Jammers' which can identify their specific phone frequency, we can jam them.

Am I sounding a bit alien???

-CB
Same applies for reverse situation also when terrorists would have formula of jamming signals on borders where soldiers use cell phones for communications. 😉 You have thought right but this reminded me of the persons who invented revolvers, bombs and armed weapons. They invented for some better use but now they are used for some worse things.
@silverscorpion • 08 Jul, 2009 • 1 like @Shalini: Nothing ever goes waste Shalini.

The situation Crazyboy quoted is one practical use of the device we are talking about.

But in a more general way, this can be used in any place where you dont want others to use a cell phone.
Like in cinema theatres or in hospitals. Classrooms, especially.. We know what we do in classrooms.

And in a more general sense, this can be used to curtail any radio communication equipment, effectively cutting of communication of a certain place. So, in some hostage situations and all, this can be used to cut off all communications and allow communications only with the rescue troops.

All right, let's first make the device. We'll think about the applications later. Wat say ya??
@silverscorpion • 08 Jul, 2009 @Godfather:

I already posted about this. There's only one part that's difficult in this project, and that is, how to find the frequency in which the phone is operating. If that's known, generating random noise at that frequency is not a matter at all. A simple oscillator would do.

But the difficult thing still remains. So, I thought if we would put that noise in all the frequencies possibly used by the cell phone, then we can jam it easily. Understand what I say??

And though CDMA and GSM operate on different frequencies, I believe noth comes under the frequency range 0.8 - 1.8 GHz. So, if we can put some noise in the whole range, then we can confuse the phone easily. But how to put the noise in all the frequencies??
@Harshad Italiya • 08 Jul, 2009 @SS :
have you study any basic circuit for cell phone jammer i got some circuit for it and right now i am collecting more data regarding this once i get collection then i want to select one circuit which we can use there are some circuits available lets see among them which we can use under this project.
@silverscorpion • 08 Jul, 2009 @GF: No, I haven't thought of or seen any circuits for this. i just thought of the idea.

And good to hear that you have something on it.
I'm doing some research here. Will get back to you if I find anything..
@durga ch • 08 Jul, 2009 @ SS
frequency?
why do you need to know a single frequency. I think its enough if you know the range of frequency . I mean you can block the frequency band rather than a specific frequency.

@ CB
Know what, the jammers used on Indian border failed 😔

@ shalini

France is already using jammers to stop people from using cell phones in movie halls where as , US as usual has banned them from being put in use.
it all depends how you use anything .
@Harshad Italiya • 09 Jul, 2009 @Durga:
Thanks for the information. why use at border failed? 😔

@SS:
i haired that id we generate the carrier frequency of that mobile range and it will superimpose on the original mobile signals.. just a wild guess. cause in the circuit i got that use to generate the particular frequency for carrier. 😕
@silverscorpion • 09 Jul, 2009 How will you find that carrier frequency??
@Harshad Italiya • 10 Jul, 2009 @SS. i had uploaded some data. i will post that link here.
there are 4-5 Different types of Jammer available and i found one report on that.

please give me some time i will comeup with some introductory information and also with that data.
@Harshad Italiya • 10 Jul, 2009 Here is that Data:
@Skywinner • 10 Jul, 2009 HEy,At can any onw will tell me at what levell your jamer projects come...???
if u reatch up to circuit level than plz. inform me...
@Madhan85 • 10 Jul, 2009 Thats a good advice for a good start ---- >
Hi I am madhan ... shall i too Join ur work
I am a communication engineer...
@Madhan85 • 10 Jul, 2009 shall it too Join ---> I Am Madhan Communication engineer.......
@Harshad Italiya • 10 Jul, 2009
Skywinner
HEy,At can any onw will tell me at what levell your jamer projects come...???
if u reatch up to circuit level than plz. inform me...
Madhan85
shall it too Join ---> I Am Madhan Communication engineer.......
@ both of you:
Welcome to the CE!
Please introduce your self using the format mention in this post https://www.crazyengineers.com/forum...roduce-yourself-template-look-here-first.html.

@Skywinner:
Why not you take active part in this project? or you want ready made project? do you know even you have ready project but you must have to understand that project otherwise it means nothing to you.. so it is better that you start from scratch.

@Madhan:
you are most welcome to this project please start searching for this project data pour your idea here and keep in touch we will surly kick out project as soon as possible. ( What you say SS? 😉 )
@silverscorpion • 10 Jul, 2009 ya, sure.
The more the better.

@Skywinner and madhan: Welcome.
@Harshad Italiya • 12 Jul, 2009
SHARATH0007
hey godfather
how do you plan to generate the range of noise frequencies needed to jam the mobile signals? ie, what sort of a circuit would you think can be used as a noise generator?. once you have the noise i suppose tou can amplify it with a power amplifier, and then transmit it ,as in a AM transmitter. is that you have in mind?
Well Sharath we can generate that much frequency using Oscillators and you are right we have to just amplify that so we can suppress the mobile frequency.
@silverscorpion • 12 Jul, 2009 @GF:
I saw the files you gave me.
The design I was thinking about had pretty much the same things.
ie, a RF frequency VCO which emits RF noise in the mobile phone range, and a small circuit to drive the VCO. Isn't that enough? What do you think??

Btw, I read there are different types of jammers, like type A,B,C etc. So, which one we gonna build? Probably type A where we only want to put noise in the range, I think.

Thanks!!
@Harshad Italiya • 12 Jul, 2009 Yep i also thinking that Class A is Best!

Lets Go ahead!!
@elektrolikit • 17 Jul, 2009 signal generator + VCO +modulator+ amplifier seems to me a good idea.
But constructing this kind of circuit from zero is not so easy.

Frequencies are very high and you need special equipments and soldering is another problem.

Best way is finding a ready circuit plan
etching it
and soldering with tons of care
or circuit will not work properly.


Here are some examples:

(This one seems very simple but im not sure it can work properly.I guess theoritically its working but power might be too weak to jam anything)
[​IMG]

(This one look like more stabile but i think needs some modifications)

[​IMG]






(this is another strange one, looks very cute)

[​IMG]
@Harshad Italiya • 17 Jul, 2009 We can do this with ready circuit but if we get some information and basic concepts then it will be helpful to get the fundamental clears. And i had worked on the PCB designs and i will try to make a full proof design.
Thanks for you suggestions. Keep them coming. One more thing is that yes that may be somewhat difficult to generate higher frequency.
@Ashraf HZ • 17 Jul, 2009
GBPPR Open Source Defense Electronics
"Protecting the World from Islam and Europeans"
www.gbppr.org
As interesting as the circuit is, this statement sorts of shows the paranoia behind the designers 😉 There goes the rational thinking of engineers, haha.
@silverscorpion • 17 Jul, 2009 Thanks for the link Ash. Also, have a look at this:

www.ladyada.net
@Harshad Italiya • 17 Jul, 2009 I had saved that file scorpion. Will check it after exam
@adinickluv • 17 Jul, 2009
godfather
Here is that Data:
Hey God father the data is encrypted can i get the password to reveal it..
I also wanna check it out the topic sounds interesting..
@Harshad Italiya • 17 Jul, 2009
adinickluv
Hey God father the data is encrypted can i get the password to reveal it..
I also wanna check it out the topic sounds interesting..
@silenthorde • 19 Jul, 2009 Im not a Communication Engineer and I know too little to comment about it. But so far as my knowledge goes:

CDMA is a spread spectrum modulation technique. If the process used is Frequency Hop( Fast or slow is irrelevant), then the range of frequencies covered will be very wide. And since it is absolutely randomly modulated using a pseudorandom code, it is extremely likely that only sweeping through the frequencies wont work.

Most of the data signals would pass without interference unharmed by the jammer.

Plz correct me if I'm wrong. I may be miles from the actual problem.

Great thread though.
@silverscorpion • 19 Jul, 2009 Yep. You are correct. CDMA involves spread spectrum and it's very difficult to interfere with a CDMA signal. But we are only trying to build a GSM phone jammer here. GSM is based on time division, and hence it should be no problem to try to jam it using random noise.
@Munguti • 21 Jul, 2009 There was a time when an RF jammer was placed at our prisons because the prisoners there were using them to scam people. They still managed to make calls by finding a large metallic bucket then making call while inside this bucket. Turn out that they were able to still make calls.
Two points here
1. the applications of an RF jammer
2. We can beat the RF jammer
@silverscorpion • 21 Jul, 2009 I don't know how that's possible.

If that bucket prevents the signal from the jammer, then it also must stop the signal from the cell phone going out. So, making a call wouldn't be possible.

In fact, this is an effective method to make one small room immune to radio signals. Implant some form of metal sheets inside the wall while building, and it stops any communication signal from reaching inside the room or going out.

This is actually used in sensitive places like embassies, etc..
@Munguti • 24 Jul, 2009 It seems to allow them to stop the jammers but not the GSM operators signals, i don't have a logical explanantion. Does anyone have one?
@jenny • 29 Jul, 2009
godfather
its
HallMark
case sensitive
hi. am jenny and i want to discuuss one thing that the circuit being disscused in this section ,i had tried it out to make it but its not working .please help me out. as its my mini project and i have to submit it in my college and i have to hurry with this project .
i had planned this circuit on a bread board and with all connections made right and still its not working.i had connected an LED with it and its not lighting up..................
pleeeeeeeeeeeaaaaaaaaaaaaaaaasssssssssssssssssssseeeeeeeeeeeeee.
helppppppppppppppppp.
all suggestions are welcome from all CEeans.waiting for reply.
@jenny • 29 Jul, 2009
elektrolikit
signal generator + VCO +modulator+ amplifier seems to me a good idea.
But constructing this kind of circuit from zero is not so easy.

Frequencies are very high and you need special equipments and soldering is another problem.

Best way is finding a ready circuit plan
etching it
and soldering with tons of care
or circuit will not work properly.


Here are some examples:

(This one seems very simple but im not sure it can work properly.I guess theoritically its working but power might be too weak to jam anything)
[​IMG]

(This one look like more stabile but i think needs some modifications)

[​IMG]






(this is another strange one, looks very cute)

[​IMG]
i m not able to design it correctly on a bread board .plz help me out in designing it (cell phone jammer).
ATTENTION all CEeans ,help!!!!!!!!!
@Harshad Italiya • 29 Jul, 2009 Can you please let me know which circuit you are implementing on breadboard?
@jenny • 31 Jul, 2009
godfather
Can you please let me know which circuit you are implementing on breadboard?
the simple one ,i mean the first circuit in my quote just above your quote,not the GBPR cell phone jammer but the circuit above it.
@krishnav • 27 Aug, 2009 hey....i was thinking jammers for my 3rd year project......can u help me too.....
if u find anything interesting please be sure to inform me as well......
thanks...
@krishnav • 23 Dec, 2009 some scientists have been able to superimpose electrical signals into microwaves and transmit it over air. It may be a form of wireless electricity transmission (wi-tricity, as it is called). i don't know much about the topic. i read it somewhere. it may be the kind of thing you are talking about.😒
@piyushh • 07 Jan, 2010 CAUTION for the ppl who are "thinking" to make jammer

well ..sometime before one delhi iit professor was arrested ...because he had attemped to help his student in testing jammer circuit ..😀.....and also one more incident ..in Hotel TAJ , mumbai .....reliance cdma was blocked.there due to jammer placed behind the bathroom some where above the tank ...u cant belive that jammer made full reliance engineers team to struggle for many days..finally the R & D team of reliance found that ..:smile:...its quite unfortunate for us that in India its illegal to try your jammer even with very short range...not permitted evn at acdmic lvl...few countries have fixed some band range for testing and R&D projects..so please guys n gals try some safe project😎
@Alice-999 • 26 Nov, 2010 Here is a articels describe detailedly about cell phone jammer:https://electronics.howstuffworks.com/cell-phone-jammer.htm
@luluka • 29 Nov, 2010 I don't about it .Just right there with you.
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