GSM detector

Wireless & IoT
1

Hello,

I am trying to make a basic GSM detector that I could use in a small room. Basically it would turn a LED on everytime a cellphone in that room received\made a call\sms.

I am thinking in using this [antenna and a TI RF power detector like the [LMH2121.

Does anyone ever used either component? Or, would [this development board allow me to do what I wanted (I would need to connect it to a uC)?

Thank you!](LMH2121TMEVAL Evaluation board | TI.com)](http://www.ti.com/product/lmh2121)](https://www.sparkfun.com/products/675)

2

too much varied RF in room.

For GSM, you’d need a bandpass filter ($$$).

Such a device is available commercially, but quite expensive.

3

Seems like an interesting project. What GSM frequencies are you after? You will likely need to discriminate against the frequencies you don’t want. Which means some sort of bandpass filter (like stevech mentioned). But I don’t necessarily think it has to be a very expensive filter. Anyways, if you can figure out the frequency band you want, an LNA coupled with either your own (built) filter or a purchased one, and the antenna you suggested, and detector you suggested could work. The main issue I think is that nearby cell phones operating in the same GSM network are extremely likely to trigger this (which may be what stevech was referring to).

4

Frequencies: 900, 1800. But for now 900MHz is enough.

Would I need a LNA?

Do you think this bandpass filter would be enough? http://www.alibaba.com/product-gs/74612 … r.html?s=p

http://www.raditek.com/FILTERS/regular/ … neric_.pdf (I don’t think this company would ship only 2 or 3 components)