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I have a question here.
Does a mobile phone emits a certain kind of signal when it sends text messages? If it does, is it possible to track it?
You can track any mobile phone when it is on but depending on your country will depend on what services are offered. There are some companies which use triangulation methods between control towers to track mobile phones to within 20-30 meters.
If you're trying to build something yourself we'll need to know your level of electronic and RF experience.
You will find that a text message will generate a certain amount of RF energy at a certain range of frequencies but apart from that you'll have great trouble to try and distinguish the difference between a text message or a normal phone registration. Maybe a text message would have a longer transmission period than a registration signal ? That would be up to you to investigate.
I'd use an array of tuned and highly directional antennas in two corners of the room. You need to look at 90 degrees from each corner maybe with 5 or 6 antennas per corner and a device to measure the signal strength of each antenna. From this you should be able to triangulate the position of the phone based on the two strongest antenna signals.
That is assuming of course only one phone is used at a time.
Thanks.
Is it a possible thesis topic?
To help you decide whether this is suitable for a thesis topic a preliminary experiment or two might be useful. Can you detect the signal from a phone? Can you demodulate it? Can you identify text-indicative patterns in the demodulated signal?
That is my problem. I don't have enough time to conduct research and experiment to test my ideas.
Surely the experimenting is the whole point of a thesis?I don't have enough time to conduct research and experiment to test my ideas.
Surely the experimenting is the whole point of a thesis?
Conducting experiments to show that something doesn't work can be just as valuable to science as showing that it does work, even if it's less satisfying to the experimenter. If you have concerns about that, discuss it with your tutor/professor or whoever will be assessing your thesis.What I'm concerned about is if it fails..
If the primary application is during an exam, i would think that any transmission from a student, whether it be voice, text message, or data would be bad. So why focus on text messages, why not just look for any phone traffic? At the risk of answering my own question, beware that phones may transmit automatically just to stay registered or to roam on a system so there are times when the phone will transmit even when you are not talking or texting or 'webbing'.
I am currently an Electronics Engineering student and is looking for a thesis topic.
I want to build an alarm system which will activate when a text message is being sent in a certain location(small radius only). After activating, the device will try to pinpoint the phone's location. It's application is for security in a classroom setting(especially in exams).
Is this for a BA, MA or PHD level thesis? Only reason I ask is it might matter what degree of complexity is required. Perhaps the following might be acceptable:
First off, it would seem to me that it would be reasonable to require that ALL cell phones be turned off for an exam.
That being the case, then you could design a receiver system to detect just the presence of a cell phone signal.
An array (or perhaps a single) antenna [stub, parabola, whatever]), might be strategically placed in the class room at, say, the center of the ceiling facing down. It (and its receiver system) could be de-tuned (and isolated) to limilt its range, and yet capture any cell phone emmissions.
That would be a sufficient indication of possibly nefarious use and would avoid any accusations of "spying" on a student's personal comms (which are being spyed on anyway, just not by you ).
<EDIT> Of course, YOUR cell would have to be off as well...
Then again, the idea might require a Faraday cage around the whole classroom, which might make the idea ridiculous. Be worth a shot, though, I'd think. Signal strength IS a factor of distance from the source.<EDIT/>
(My emphasis)It's for BA. Maybe a cellphone signal detector would do it. I made things complicated .
But I want to build not only a device that can detect but also pinpoint it. Thanks