Cell Phone Signal Detection

Computers & Mobile
Cell Phone Signal Detection
A schematic of a half-wave dipole antenna connected to an unbalanced coaxial cable.

The perfect example of a project that could use that extra little push to overcome specific technical hurdles or design needs, Sophi Kravitz from MIX Engineering has been working on cell phone detection for several months now. From coming up with a concept, to beginning research, then experimenting with available hardware, and finally, publishing results and fielding feedback, this is how an idea becomes reality! Speaking of her project, she says,
Road to Maker Faire Challenge

The circuit I’m working on simply detects (a power level) when a call, text, or email is made. It uses an antenna to detect the signal, which attaches to an RF detector to output a power level. Basically these chips are little power meters… Most of the RF detectors go to an input level of -60dBm, which means an amplifier will be required in between the antenna and the RF detector. Typical opamps don’t have the required frequency response, so a specialized RF amplifier is the type of amplifier needed.

Having achieved results already, sometimes funding is all a project needs to finally take off. So last week, Sophi submitted her project to the Road to Maker Faire Challenge, where one lucky maker will win $2,000 to fabricate their idea and bring it to Bay Area Maker Faire in May! Best of luck to you Sophi. Now, are you ready to accept the challenge? Apply now!

20 thoughts on “Cell Phone Signal Detection

  1. Cell phone signal detection part 5 – learning from RF Rockstars » MIX Engineering says:

    […] did want to report that I got a small mention in MAKE blog which was SUPER […]

  2. Avtar chettri says:

    its not possible to detect phone when they are not in use? can we detect phone weather it is on or off by RF signal?

    1. Nick Normal says:

      I can’t think of a single type of signal technology that can’t ultimately be detected by some other type of technology!

  3. jayendra says:

    hello sir,

  4. sangamesh123 says:

    Is it possible to find a cell phone when it is just switched on and connected to a network?
    Note: no operations like call, message or email is in process

  5. Sophi Kravitz says:

    Hi Sangamesh,
    Cell phones find each other when they are switched on, so it is possible!
    In the “About Phone” option on my phone the network type and strength is shown (for example, -108dBm). As you approach another phone, the strength shown jumps around a bit.
    Also shown is the type of network, roaming or not, and if the mobile network is disconnected.
    Hope that helps-

  6. ventan says:

    please help.. I’m doing a prototype of mobile phone detector integrated to a CCTV that can detect cellphone activity within a room. the output will be display in PC where it can detect mobile phone whether it is active or on idle mode. the CCTV camera view will just be overlay in a graphical user interface map. thanks

  7. jesse says:

    i’m trying to set out a project about prohibiting the use of mobile phones in examinations room,, i need to set a detector to detect if candidate has any mobile phone either switched on/off before entering. The system should give an alarm in case there is any mobile phone.

    I need your help into set this project or how do i start????

    1. Sophi Kravitz says:

      Hi Jesse-
      SWEET! That’s one of the applications I made my project for. The chip I used works on the 840 MHz band from 8 feet away, but not for all carriers (Verizon works perfectly).
      I used an Analog Devices chip AD8363 because it measures if there is power being generated wirelessly on a certain frequency.
      You can even buy an evaluation board (around $100) for many of their RF detection chips, which is where I recommend you start. Well…first watch the tutorials about RF detectors on the analog site, then buy the eval board.
      Then let us all know how it goes~! :D

  8. mobile phone detector says:

    hi guys
    mobile phone detectors are very useful to find any mobile device .this device uses an antenna to receive signals.which attaches to an RF detector to output a power level.this s really nice and i appreciate the information.thanks

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I'm an artist & maker. A lifelong biblioholic, and advocate for all-things geekathon. Home is Long Island City, Queens, which I consider the greatest place on Earth. 5-year former Resident of Flux Factory, co-organizer for World Maker Faire (NYC), and blogger all over the net. Howdy!

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