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Chronos User Discussion / timing of external trigger
« on: September 06, 2023, 08:16:42 AM »
Hi,
I'm seeing an unexpected delay when triggering externally via the BNC connector. In a test I'm recording a LED that flashes at 150 Hz for 100 ms. When it stops, I supply a trigger signal. This timing is more or less exact, I checked this with an oscilloscope.
Here's the signal I'm sending (the time axis is in expected camera frames):
The camera is set to record 2000 frames at 8245 fps. However, it doesn't seem to trigger at the time of the trigger signal but ~44 ms (~360 frames) later. The trigger timing in the camera is set to default - all 2000 frames are pre-trigger, and there are no post-trigger frames.
Here's what the camera is actually recording:
Is this expected? What to do about it? What I actually want to do is record 500 frames, and there I can't really tolerate a 360 frame mismatch.
Thanks.
I'm seeing an unexpected delay when triggering externally via the BNC connector. In a test I'm recording a LED that flashes at 150 Hz for 100 ms. When it stops, I supply a trigger signal. This timing is more or less exact, I checked this with an oscilloscope.
Here's the signal I'm sending (the time axis is in expected camera frames):
The camera is set to record 2000 frames at 8245 fps. However, it doesn't seem to trigger at the time of the trigger signal but ~44 ms (~360 frames) later. The trigger timing in the camera is set to default - all 2000 frames are pre-trigger, and there are no post-trigger frames.
Here's what the camera is actually recording:
Is this expected? What to do about it? What I actually want to do is record 500 frames, and there I can't really tolerate a 360 frame mismatch.
Thanks.