Hi,
I have viewed Keysight videos and instructions on using a pattern matching timeout trigger mode to demodulate ASK RF. In particular, Manchester Encoded although the same principle should apply to any ASK RF signal.
App note :
https://assets.testequity.com/te1/Documents/pdf/keysight/AutoKeyFobCommunication-an.pdfVideo :
The technique is to set up a trigger on the condition where the rising or falling edge has a significant time gap after it before the next rising/falling edge. This would mark the end of a burst of carrier.
The method necessitates the detection of all subsequent multiple trigger points within the same capture. By using the BNC trigger output to feed another channel, a logic level replica of the ASK signal appears on the screen.
Seems pretty neat and I wanted to replicate that with my Siglent SDS2504X+.
But I can't get it to work. It appears that once the first trigger has occurred after arming, the scope either does not bother detecting subsequent triggers - or it detects them but doesn't send them to the trigger out. So I don't get a nice replica of the demodulated waveform.
I left wondering about a few things now.
1. Is this little hardware demod trick outlined by Keysight something that is in general use ?
2. Does the Siglent work in a different way to the Keysight and thus not able to replicate this process ?
3. If the Siglent can't replicate this trigger process, does anyone have any other bright ideas about how to implement it on the Siglent ?
Obviously I can do it outside of the Siglent and in fact moved my project forward by doing just that. I used an external envelope demodulator. You can see from the two below screenshots that it works nicely. I reproduce them to aid in understanding what I am trying to achieve, lest I haven't made it very clear.
So really this question is a point of curiosity and learning for me and maybe there are others who might take an interest also.
Thanks
Eloso