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Udo, On 20/08/2018 9:43 AM, Udo van den
Heuvel wrote:
Michael,With kernel level timestamps back in user space, paired with the GPS Timemark message, you can do whatever you want with them. Correct. You need both sides.I'm held up deciding on the method of sending messages for each Trigger Timestamp from the kernel module back to user space. With PPS, you get one offset from system time, but with incoming latency including interrupt lag. Using Timemarks give you FOUR kernal level latency ports going high/low with kernel timestamps. You don't need the higher latency PPS for calculating offsets and disciplining. See the thesis results. Maybe make it an elaborate PPS device that can also be read?Define "elaborate PPS device". Once this LKM is working, you can make a copy and play with it. Perhaps with using the greater precision of CPU Time - if you can find a way that will keep the LKM in the same core for the duration of your measurements. Michael |
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