2
\$\begingroup\$

What piece of hardware am I looking for to observe the transmitted radio signal? Would an oscilloscope come in handy here? is this a 2-channel RF remote, a 3channel RF remote, or something else?

My goal is to build my own circuit that emulates this circuit. Would I require a bus pirate for this? I realize it might be much easier just to buy a new remote but I'm using it as a learning experience rather than a cost saving endeavor.

googling the IC, a message board mentions its probably a custom IC. The IC has the following printed on it: 0412 SEMEFAB 051-8728 0821-D (LF) D[big letters, on right] enter image description here

\$\endgroup\$
  • 1
    \$\begingroup\$ The transmission frequency is the most probably determined by L1-C6 oscillator. I guess it has 1 RF channel and it sends 1 of 10 selectable different signals (presets) which are modulated on the RF frequency. \$\endgroup\$ – Cornelius May 28 '14 at 19:49
  • 1
    \$\begingroup\$ If you can get access to the modulated digital signal before it hits the RF stage this might be easiest. However this might be harder if there is one monolithic IC that does all of the processing. Depending on the frequency of the device your oscilloscope might help if you make a loop and clip the ground wire to the probe, but it's likely to be in the ISM band (4xx/8xx/9xxMhz) which isn't going to appear on your scope. \$\endgroup\$ – David May 28 '14 at 19:50
  • 1
    \$\begingroup\$ You might check the signal at the base of Q1. \$\endgroup\$ – Cornelius May 28 '14 at 19:51
  • 1
    \$\begingroup\$ With regards to equipment the traditional method would be a spectrum analyser. Nowadays you might get away with a HackRF and GNU Radio. \$\endgroup\$ – David May 28 '14 at 22:38
  • \$\begingroup\$ This looks like a 300-310 MH single channel garage door opener such as multicode 308911 \$\endgroup\$ – user56237 Oct 15 '14 at 3:18
3
\$\begingroup\$

I'd definitely recommend getting a BusPirate, you can probably find the frequency in the developer docs and then do something like this:

http://ms3c.wordpress.com/2011/06/19/basic-rf-sniffing-with-the-bus-pirate/

Failing that you can probe all the pins with the BusPirate logic analyser mode and just observe the transmit waveform.

\$\endgroup\$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.