EEVblog Electronics Community Forum
Products => Test Equipment => Topic started by: Circlotron on May 25, 2018, 11:40:31 am
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Rigol DG1022Z function generator set to 10v p/p sinewave.
If I go from 100,000 Hz to 100,000.000,001 Hz the output voltage increases by approx 200mV p/p. Both channels do the same. Anyone else noticed this?
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I have a DG1022Z, how are you doing the measurement?
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How do you measure?
Anyway, there are many reasons, including resonance, incorrect measurements, calibration, etc.
PS I don't get what "100,000.000,001 Hz" means. Is it 100kHz?
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So I just ran a test; 50 Ohm output set on the DG1022Z, 5 Vpp into a 50 Ohm coupler on my DS1054Z. When I went from 100,000.000,000 Hz to 100,000.000,001 Hz, the output decreased from 5.04 Vpp to 4.92 Vpp, a difference of 120 mVpp. It's a definite change that occurs at that specific point, leading up to and after the point, the voltage is steady.
There's probably some lookup table that switches over at this point but I'm unconcerned. What I typically do is set up the DG1022Z to close to what I want and then monitor the voltage applied at the point of insertion using an accurate multimeter while tweaking the controls to make sure the input is at the desired parameters.
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I just had a 1 metre length of coax from the sig gen with alligator clips on the end, clipped to the X10 scope probe. Not terminated or anything. I’m not particularly fussed about it, just hoping someone for Rigol reads these columns and somehow gets included in a firmware update.
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PS I don't get what "100,000.000,001 Hz" means. Is it 100kHz?
Very very slightly higher than 100kHz
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So I confirmed the issue you identified - maybe Rigol will look at it, maybe not.
I'm surprised no one has figured out how to unlock it to be a 1032 or 1062 yet.
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I think it's a calibration issue. In "DG1022 Function/Arbitrary Waveform Generator Calibration Guide" everything up to 100kHz is low frequency and calibrated separately. See "Low Frequency Flatness Adjustment" and "Range Flatness Adjustment".
Keep in mind higher frequencies are calibrated with 50 Ohm load.
Disclaimer: I have zero experience in calibration.
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I have seen this same level change above 100Khz happen with a Rigol DG4062.
In this case it was within the specified +/- 0.1dB Flatness into a 50 ohm load.
I suspect that it is related to the internal calibration table.
Regards.
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In "DG1022 Function/Arbitrary Waveform Generator Calibration Guide"
Where can we find this publication?
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Where can we find this publication?
Uhm, first link in google :).
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When I looked (before I asked) it only referenced this thread. I’ll have to try again!
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When I looked (before I asked) it only referenced this thread. I’ll have to try again!
Just in case, here is the link: https://www.eevblog.com/forum/testgear/rigol-dg1022-how-to-update-the-firmware/msg583501/#msg583501 (https://www.eevblog.com/forum/testgear/rigol-dg1022-how-to-update-the-firmware/msg583501/#msg583501)
(or direct link https://www.eevblog.com/forum/testgear/rigol-dg1022-how-to-update-the-firmware/?action=dlattach;attach=128726 (https://www.eevblog.com/forum/testgear/rigol-dg1022-how-to-update-the-firmware/?action=dlattach;attach=128726) ).
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My fresh out of the box new DG1022Z this morning does the same. Drops 25mV on Hi-Z input but only 1mV on 50 ohm load ergo this looks like it's calibrated for a 50 ohm load.