Siglent1104 oscilloscope channels lagging
First I noticed that clock begins before chipselect gets pulled low on SPI. After eliminating potential sources I started to suspect the scope. I connected all 4 channels to function generator at different frequencies and observed 25ns gap between channel pairs. The probes were all the same 100Mhz stock probes that came with the scope set at x10, the 'deskew' was 0 on all channels. The 25ns was constant across different frequencies. On/off, auto calibration and factory reset did not fix the issue:
What could be the reason for this? Is this a bastard scope?
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| User | Comment | Date |
|---|---|---|
| Elleanor Lopez | (no comment) | Jul 18, 2022 at 11:55 |
It was a firmware issue. SDS1xx4X-E Firmware Revision History And Update Instructions
The hardware delay between ADC acquisitions was not accounted for. I flashed the scope with new firmware and the delay is gone
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If all four channels are really connected to the same signal in the pictures you show, then there is indeed some skew between pairs of channels.
Try swapping probes to see if the lag goes with the probe or the channel.
Also try on the 1x setting. That should have less parasitic low pass filtering. Make sure the compensation of each probe is adjusted correctly. The compensation adjustment can have an effect on delay.
It looks like pairs of channels have the same lag. Is this the kind of scope that has plugin modules? If so, is the exact same model plugin installed for all channels?
Check the datasheet to see what the worst case skew can be when using the stock probes at 1x and 10x.
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