> how does Atlas computes the `precision` field?

I believe the format_8bit() function in the probe's ntp.c is responsible
for the conversion [1].

4x10E-6 would be an NTP precision value of -18 (3.815 us), which isn't
great nowadays, but I think not completely out off whack.

[1]
https://github.com/RIPE-NCC/ripe-atlas-software-probe/blob/57515ad8a4a84f19af0d05c9696fd8d3304408eb/probe-busybox/eperd/ntp.c#L302


On 09.07.25 09:47, Giovane C. M. Moura via ripe-atlas wrote:
> Hi Philip,
>
>
>> Looking at the code, it seems that the Atlas NTP measurement
>> computes the offset with exactly the opposite sign compared to the
>> NTP RFCs.
>>
>> I never noticed before.
>
> Thanks. Since we are on it, the timestamps are _correct_ , so any user
> can still compute the offset based on the data
>
> Question: how does Atlas computes the `precision` field?
>
> I had someone telling on the NTP pool that `Precision from RIPE Atlas
> probes looks rather low to me (4x10E-6).`
>
> Thanks,
>
> /giovane
>
> [0] https://community.ntppool.org/t/site-to-evaluate-ntp-servers/3931/2
>
>
>
>
>
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