Rigol DS2000 Firmware 00.03.03.01.00 Comments and Bugs

[Teneyes]

Now the Digital Filter with Bandpass filter set to 3-4KHz and the input of a sweep from 2-5KHz
1 Sawtooth wave
2 Sine wave
3 Square wave
Does anyone know the equations that are used here???

[Teneyes]

Here is a sweep of 5-18KHz sine wave with a Digital Bandpass filter
1. Bandpass set from 8 - 12 KHz
2. Bandpass set from 8 - 12 KHz but zoomed 1 step from 500us/div to 200us/div
3  Still Zoomed  with Bandpass set form 4-5KHz

Question : How should the Zoom work when Digtal filter ON??

Is this a Bug??

[Teneyes]

More testing on the Zoom of digital Filter Function
Here I test a LoPass Dig. Filter : Normal and Zoom
1  LoPass at 20Khz and sweep from 5-40Khz
2  LoPass at 20Khz and sweep from 5-40Khz  Zoomed
3  LoPass at   8Khz and sweep from 5-40Khz  Zoomed

From this, I conjecture that the FW is using the 5oous/div time base, with the Zoomed Data and therefore the Digital Filter function is incorrect by a factor of  200/500.
Therefore the Cutoff frequency becomes 2/5 of 20KHz=8KHz.
I conclude it is a Bug!!

In zoomed mode the filter slope should expand by the zoom factor (display division)