Hi,
In order to get a good understanding about the THD of different function generators,
I started up my measurement computer to do some measurements with a very good Soundcard, this is the:
M-Audio Delta AP 192.
The yellow dashed line in the FFT window, indicates the bandwidth within which the THD is measured.The Sinus of the scope picture does not look very clean, this is partly due to the RDC session I use to operate the measuring computer, so these are image artifacts and not a problem with the test signal.
The orange box shows the RMS level of he measurement signal.
For each generator this is set to 2V RMS, there are some exceptions, which I will indicate later.
Also a good sound card has a "sweet spot" this is only important when measuring the generator distortion of the Audio Precision measurement set.
All my function generators are well above the distortion and noise of the sound card.
The settings of this soundcard are these:
192Khz sampling
24-Bit
1-Channel
FFT = 1048576 points
Window = Kaiser-7
Averaging = 4x
Measuring software =
Multi-Instruments pro 3.9======================================
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Let's start with the Siglent SDG1032x just like the previous measurements, here the measurement signal is 10KHz Sine at 2V RMS.
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The bigger brother Siglent SDG2042x just like the previous measurements, here the measurement signal is 10KHz Sine at 2V RMS.
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This is the HMF2525, measurement signal is 10KHz Sine at 2V RMS.
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This is the Rigol DG4162 Chanel-1, measurement signal is 10KHz Sine at 2V RMS.
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This is the Rigol DG4162 Chanel-2, measurement signal is 10KHz Sine at 2V RMS, the distortion of this channel is lower...
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This is the generator output of a OWON SDS272s, measurement signal is 10KHz Sine at 855mV RMS, the max. level.
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This is the generator output of a Silent SDS2100x plus, measurement signal is 10KHz Sine at 1.05V RMS, the max. level.
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And now to show the limits of the measurement system two measurements of the distortion of the generator in the Audio Precision measurement set, the first measurement is again 10KHz and then performed now with a measurement signal that is the "Sweet Spot" of the total system, the level is just below 3V RMS.
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And de last one, now at 1KHz, Sweet Spot is 2.5V RMS
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Good, now it's time to start working on my business administration again, which I like a lot less, but it has to be done.
Kind regards.
Bram
PS
Thanks mawyatt for finding the error, yes SDG1042X should be
SDG2042X!, my bad