I just purchased a new Siglent 1104X-E and was looking at an external PPS signal and for some reason if I connect two probes to the same signal on channels 1 and 2, the two traces over lap as you would expect, but as soon as one probe is moved to chan 3 (or chan 4) there is a ~30ns offset between the two. In the attached image, the Purple and Yellow trace are chan 1 and 2 and the Blue trace is chan 3. They are all connected to the same signal. Does anyone have any ideas? is there something wrong with the calibration? or am just missing something. Any help would be appreciated.

 

ah, nevermind. it looks like there are a bug in the firmware that was corrected in the latest firmware V6.1.37R9

 

ah, nevermind. it looks like there are a bug in the firmware that was corrected in the latest firmware V6.1.37R9

Not exactly.
There have been HW changes for one unknown reason or another and as these scopes use 2x 1GSa/s ADC's the new components introduced a 'channel pair' skew that needed to a targeted correction with a new firmware release.

V6.1.37R9 Release Notes: (Copied from the Siglent website so please excuse the poor English)
Fixed the problem: The skew of the two ADCs is not accuracy for hardware of 09 version (System Status shows Hardware Version: 09-xx). The other hardware version has no this problem.

 

Not exactly.
There have been HW changes for one unknown reason or another and as these scopes use 2x 1GSa/s ADC's the new components introduced a 'channel pair' skew that needed to a targeted correction with a new firmware release.

V6.1.37R9 Release Notes: (Copied from the Siglent website so please excuse the poor English)
Fixed the problem: The skew of the two ADCs is not accuracy for hardware of 09 version (System Status shows Hardware Version: 09-xx). The other hardware version has no this problem.

ah, ic. thanks for the explanation.