Hi again.


I was wondering what people thought about a program that would simultaneously take a reading from all RF devices on all channels and display that info.

Kind of like a realtime, or snapshot, of BT, Wifi, infared, FM, gsm and 3G (missing any?).

I'm sure you could get crazy and use GPS and/or camera distance to map or photograph points of high "noise".

But really just a txt display of levels would be cool.

.....I want my tricorder damn it. :P

Probably the cooler more modern scenario would be.

"woah, check out that building, it's got mad RF coming off it."

"wait, it's not the building, it's the guy in front of the building."

"he must have an N900, bet his battery dies in less than an hour."

I hope you all get my idea, and I hope it's interesting.

Sounds really cool. It would be a ***** to implement though.

You can't detect other gsm transmitters besides the cell tower your n900 happens to be talking to.

Should be possible to scan fully for wifi and bluetooth though, to a certain extent.

BTW, there are websites out there who try to map out the locations of cellphone base stations

I would also love such an application for the N900

i think from what you say that you want to use the N900 as a spectrum analyzer, and its a great idea to have something like that in your pocket and scan frequencies from sound to microwave (you missed the Mic) , but i hate to be the one to say it, it can not be done , its a hardware limitation, (for all except the audio and maybe FM if the SNR value can be read from the Internal FM receiver)
and let me explain why
first the N900 got only an infrared transmitter no receiver and second the best that can be done with WiFi is something like net stumbler that will draw a plot of the signal strength of the Detected WiFi devices,
a WiFi device cannot by any means scan a spectrum of frequencies like a real spectrum analyzer dose simply because it was not designed to have an interface or report the low level data of the radio receiver, most of the low level operations are handled by the WiFi Device's Firmware the same applies to the blue-tooth and GSM (2G and 3G)

i have interfaced GSM and blue tooth modules to micro controllers and built my own hardware for a car computer, and from all the data sheets and all the interfaces i have seen, most of the information that can be used to make something like this is handled internally inside the receiver itself and cannot be read from outside.

Please create a Brainstorm item!

This gets on to hardware...you could use a BT spectrum-analyzer or a spectrum2audio converter to feed the n900 over jack.

The really usefull thing could be a RF analysor for the Radio transmitter. Scan the spectrum before and take automatically a free frequency (or view only) with the most band gap.

have you guys ever heard of something called the 3rd harmonic?
http://www.physicsclassroom.com/mmedia/waves/harm3.cfm

Let me explain...
A while ago my next door neighbour was experiencing some interference with his sky tv and while I was on holiday the interference stopped, then upon my return home, the interference started again, next minute I receive a knock at my door from the UK body that allocates the frequencies trying to figure out what I was using that was interfering with my next door neighbour's sky tv....

it turned out that my then wireless broadband signal (using LOS dish) were bouncing of some walls and also bouncing off his sky mini dish and causing interference at another frequency, i think around a multiple of x3, hence called the 3rd harmonic... basically if you listen for a signal on other frequencies that can be divided/multiplied by x2/x3/etc (the third harmonic being the stronger), then you could identify other RF nearby...

...in my case tests showed that the 3rd harmonic interference was being picked up at around 300 meters away very strongly.

the outcome of this was that whoever in the uk allocated the air frequencies originally did not think of the 3rd harmonic and I was not asked to stop using the service.

Do you know where i could find info on how to send bluetooth commands to an arduino from a n900?