Understand, back to your topic:
If your time allows you, can you make a short video from the bode menu ?
As written before the manual is a little bit meager.
I assume the phase measurement is in there
edit: page 142 in the English DHO900 user guide
Understand, back to your topic:
If your time allows you, can you make a short video from the bode menu ?
As written before the manual is a little bit meager.
"Meager" is a polite word here; unfortunately the series hasn't been out long enough for someone to write a relevant "dummies" book.
My next experiment is to build the simple network in a properly shielded box, but I'm busy elsewhere until next week.
I also need to figure out how to increase the drive voltage: I believe the default I used here is only 200 mV pk-pk, but the generator can do 5 V pk-pk max.
You shouldn't need a shielded box for this type of simple Bode measurements, now if you are measuring the Open-Loop response of a op-amp in Closed-Loop form (injecting a small signal in the loop), then maybe shielding might be required.
Wonder if the Bode implementation utilizes any sort of frequency selectivity like other implementations?
Best,
The more I read real user feedback now that specimens are starting to trickle in (and it has been few months already since it was "released") I see that it is even worse than I expected (I thought they would cleanup things a bit by now)..
These scopes are in alpha stage of development as of today... I actually expected much better from Rigol. Hope soon this gets much better, otherwise users will not be happy...
I assume the phase measurement is in there
edit: page 142 in the English DHO900 user guide
That is something else, a phase measurement in Measurements. It is not a plot but single point phase measurement.
Bode Plot is something completely different.
That looks like the same problem I reported, and I am also disappointed.
Every time I obtained a scan, I noticed the non-monotonic behavior as it was displayed ("wiggles"): clearly visible even with the narrow display range.
The reason I graphed the results (.csv file) on a graphing program was that I could not adjust the scale on the screen: I assumed that I needed to study the manual more.
In my graphs, the x-axis is the frequency values listed in the first column of the .csv file.
Rigol only advertises the Bode Plot function to be used with an isolation transformer to evaluate feedback stability, and it does announce the voltage and phase margins for that measurement.
The first scan I did (not posted here), I had an attenuator on Ch1 so it would look more like a feedback Bode Plot (gain above unity at low frequency), and those margins were calculated.
Is there a useful address at Rigol to report bugs?
I assume the phase measurement is in there
edit: page 142 in the English DHO900 user guide
That is something else, a phase measurement in Measurements. It is not a plot but single point phase measurement.
Bode Plot is something completely different.
Since doing it the slow way (point per point and making your own graph) it is measuring stable/correctly (luckily), most likely they changed something so the timing for the measurements changed and screwed the automated measurement script that was probably working before.
So I'm sure it's an easy fix, just get the measure timings right. (it may end up slower though)
I found the same "wigglyness" of the traces while at least a monotony should be shown in case of a simple low pass. Maybe they designed too many "wiggles" in the traces on the instrument's PCB...
I found the same "wigglyness" of the traces while at least a monotony should be shown in case of a simple low pass. Maybe they designed too many "wiggles" in the traces on the instrument's PCB...
Just pondering how they do the phase/amplitude calculation, the way that comes to mind is an FFT of CH1 and CH2 and extract the amplitude and phase from that. But they would be shortish sample sizes for speed and not synchronised to the input sine. This would lead to both phase and amplitude errors perhaps even the ripple seen. Not sure if that is how they do it or it is even the best way.
I believe the transformer is required in order to inject the input signal into the "guts" of a feedback amplifier, without disconnecting the feedback, to get a Bode Plot of the loop gain/phase for stability analysis.
The measurement itself, however, should be a frequency scan measuring the relative gain and phase of two channels.
The measurement menu has enough functions to measure relative gain and phase at a single frequency.