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!

screenshot of cubicsdr

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.

  • \$\begingroup\$ FYI: Your screenshot appears to be tuned to 91.5 MHz (in the middle of the FM radio band), not 915 MHz. \$\endgroup\$
    – user39382
    May 1, 2018 at 23:37

1 Answer 1


enter image description hereIt looks like 433MHz and for trace width ~0.1" ).5oz + 1oz plating. (ballpark). The equal length at right angles prevents null patterns from end directions.

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.


  • \$\begingroup\$ thanks. I must admit I have trouble following your explanation due to my limited knowledge. However, I tried each and every frequency of the ones listed in the table you linked to on Wikipedia, with a bandwidth of 25kHz (imgur.com/a/6cwMHkM shows the last channel). Each time I pressed a button or two, hoping to elicit a change in the display of CubicSDR, but never was there any that could be interpreted as a reaction to my button presses. I'll try other frequencies? \$\endgroup\$
    – jfix
    May 2, 2018 at 20:32
  • \$\begingroup\$ Always start with a wide resolution of 1MHz then zoom in \$\endgroup\$ May 2, 2018 at 23:30

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