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I'm wondering about a method to find an unknown frequency. I want to intercept the data from my hydro meter, but I don't know the exact frequency. I'm pretty sure it's in the range 902-928 MHz, but my rtlsdr only has a bandwidth of about 2 or 3 MHz. I'm new to radio stuff and signal processing, so I'm wondering how I hone in on the data. I read the meter also uses frequency hopping.

Ideally I'd like to setup my rtlsdr dongle to rotate on bands like so:

listen on 902 for an hour listen on 904 for an hour listen on 906 for an hour ... listen on 928 for an hour

Then I want to only record something when there is a "blip" - this way I could take these recordings and analyze them.

Is there a better way?

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Does your hydro meter have an FCC ID? If it has, then there's extensive documentation on the system on the FCC's website, including a detailed description which frequencies, bandwidths and powers the device uses, and possibly also which modulation.

Your meter probably works in an ISM band, meaning that unless you put everything in an RF-proof box, there will be a lot of stuff going through the ether around the frequencies you want to observer, so your 1h listening mode doesn't sound too promising. Also, there's no guarantee there's a "blip" – transmit power might be really low and spread out over a larger bandwidth (search for "spread spectrum" technology to understand how).

If observation is your best approach, I'd go for using gr-osmosdr and the osmocom_fft -W tool that comes with it.

于 2015-12-15T12:15:42.357 回答