Bug 1010 - Analogue and Digital channels not in exact sync
Summary: Analogue and Digital channels not in exact sync
Alias: None
Product: libsigrok
Classification: Unclassified
Component: Driver: fx2lafw (show other bugs)
Version: unreleased development snapshot
Hardware: All All
: Normal trivial
Target Milestone: ---
Assignee: Nobody
Depends on:
Reported: 2017-08-10 17:37 CEST by skaggmaster
Modified: 2018-10-02 18:01 CEST (History)
3 users (show)


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Description skaggmaster 2017-08-10 17:37:53 CEST
Fiddling with my CWAV AX clone, I see that there is a lag of about 6 us between the analogue channel and the digital channels in PulseView. Analogue is behind. 
(Or around 4 samples at 500 kHz / around 2 samples at 200 kHz). Maybe a "user definable offset" can fix this.
Comment 1 Gerhard Sittig 2017-09-17 12:44:31 CEST
It's assumed that the skew is a property of the hardware in the capture device 
(very probably the ADC).  The software reflects the samples in the very way 
they are available from the FX2's perspective.

It's uncertain how generic an issue this is (applicable to _any_ mixed signal 
acquisition device? to arbitrary input files as well?).  I'd suggest to 
capture to disk, and optionally postprocess the analog part of the capture, 
before loading the file for subsequent inspection.  This might be as simple 
as dropping the first few bytes of the first/only analog chunk, and padding 
the last/only, to "shift" the analog trace by a desired amount of sample