I recently bought a DSO4104C, which I like very much. I've been trying to use the FFT math function and there are the bugs that I can see.
1) The FFT divisions are wrong: I tested with a triangle waveform and the 3rd harmonic was 40 dBV lower than the fundamental, it should be 20 dBV lower. This is known and can be calculated, I took the the CSV of the waveform and used a maths program to double check. It looks like the divisions are twice what they should be.
2) When using the cursors on the math fuction, using FFT, the cursors don't track.
3) The cursors don't read the correct value, (doesn't match the axis on screen), when the FFT reference level is not 0 dB.
The scope is very nice and it would be good if you could fix the above.
Thanks.
Author: amy Time: 2018-5-15 16:14
Sir, we will test and reply you later.
Please wait for a while. Author: Demishrike Time: 2018-5-20 18:29
Thanks, I'll wait. Author: amy Time: 2018-5-29 13:55
Thank you, I've updated using the above file and items (1) and (3) are both fixed which is great. The FFT function measures correctly now and the cursors display the right value.
However, item (2) is still not fixed, the cursors still do not track see the image below. This is not a problem for me but just want to let you know so you can fix it.
Thanks again for you quick response in fixing the FFT measurement.
Author: amy Time: 2018-6-9 15:41
Sir, please download the firmware again to update.
Any fuirther discussion, please let me know.
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