Any idea what the voltage on the pin that you probed is supposed to be?
I don't have anything that can measure the true voltage, or have any idea what it is supposed to be, however it is powered by a single 12v 23a battery. This remote usually gets like ~50-60ft range to the car with the receiver so I do think it is being attenuated heavily, as the output voltage swing really isn't enough to transmit effectively IMO.
How could you know?
The -3dB BW of these units is ~125 MHz so at 3 times that frequency the roll-off will be so horrendous and give NO possible indication of the true amplitude of the signal.
I was going off of that there would need to be more signal swing for the modulator (I was probing the output of the PA/oscillator for the 433.92MHz; pic attached) as it’s going to have a small loss and then it would still need a few mW of power for the actual signal leaving the remote.
Hello All,
I realize that this shouldn't be possible, but ...
Why not?
You've got 1 GS/s sampling rate so your nyquist frequency is 500MHz. You can see signals up to that frequency.
The thing you can't do is measure their amplitude at that frequency. They will be very attenuated.
I was thinking it wouldn't be possible because of the attenuation by the frontend, but it must roll off then go back up near this frequency (or much before)
Also, this morning I had a little extra time so I used a 50? terminator + a bit of coax and I got the same thing with a different amplitude, hopefully with less reflections & impedance transformations, but still the amplitude will be useless. I think all the remote is doing is loading the output to adjust the amplitude to send the code. (at a quick glance at least) (I just noticed I was on DC coupling not AC this time.
I can redo later if anyone wants me to.)