# How to observe the signals of a radio remote control using CubicSDR?

I have to admit I'm a complete newbie with regards to radio frequencies and such ... :-(

Thanks to this site I've been able to find out what transceiver is being used in the remote control I'm investigating [1]. The datasheet is here [2].

I have a USB-based SDR (R820T from NooElec) and CubicSDR. Now I'd like to find out what happens when I push a button on the remote control. But I have no idea what band to use (FM? What is FMS? NEFM? you see my problem ... ;-) ).

From the datasheet, I've understood that the remote control could transmit signals on several frequencies, such as 433 MHz, 868 MHz or 915 MHz. So I tried to set the observed frequency centre in CubicSDR (see the screenshot with 915 MHz, I think!). But when I press a button on the remote control I don't see any change in any of the different windows.

I'd very much appreciate your help with this. Any pointers to educate myself are appreciated as well!

PS: Obviously, I've looked at the CubicSDR documentation (http://cubicsdr.readthedocs.io/en/latest/) but I can't make head or tails of it.

• FYI: Your screenshot appears to be tuned to 91.5 MHz (in the middle of the FM radio band), not 915 MHz. – duskwuff -inactive- May 1 '18 at 23:37

Measure antenna length for l=λ/2, compute half wave carrier f, look for 100kHz FSK more or less using $l=λ/2$ or may be limited to 25kHz BW FSK anywhere from 433.050 MHz to 434.790 MHz. Check use in your country.
$f=\dfrac{1}{2∗l∗c∗\sqrt{e_{R_{eff}}}}$ for c=3e8m/s e=4.5 and with estimate track width and thickness $e{_eff}$=2.9 approx. or less.