Trigger issues on 0.94-RC19 OS verison

[positron]

Hello,

I was wondering if anyone else is having trigger issues on the latest OS release, version 0.94-RC19? When I put a >100 000 Hz sine or triangle wave into the input, and use the ScopePro application, the triggering does not seem to always happen on the selected slope. Sometimes, the downslope will trigger a waveform capture. This is on Normal mode, upslope trigger, no offset. This does not happen when a square wave is used as the waveform input signal.

I can post a Youtube video capture of this happening if anyone is interested. Cheers and thanks.

[Nils Roos]

The positive edge trigger fires when the signal was below the threshold (minus hysteresis) and then goes above the threshold from one sample to the next. With a noisy signal and a low hysteresis this could occur on a downward slope.

When you go to higher frequency signals - and thus, presumably, to a lower t/div setting on the scope - the decimation will be reduced when crossing certain magnification factors. Lower decimation leads to a noisier signal. You could increase the hysteresis setting to counter that.

[positron]

The positive edge trigger fires when the signal was below the threshold (minus hysteresis) and then goes above the threshold from one sample to the next. With a noisy signal and a low hysteresis this could occur on a downward slope.

When you go to higher frequency signals - and thus, presumably, to a lower t/div setting on the scope - the decimation will be reduced when crossing certain magnification factors. Lower decimation leads to a noisier signal. You could increase the hysteresis setting to counter that.

Thanks Nils, I will give this a try. Where is the hysteresis setting found for me to modify?

[Nils Roos]

Hmmm, just had a look, in the free app the hysteresis is a constant in the code (63 counts, see here). I don't have the ScopePro, but if you don't find a setting for it there, it may be that it's also constant.

If that is indeed the case, I'm sorry to have led you on. Maybe suggest a hysteresis setting to the RP guys as an improvement ?