[time-nuts] Re: Primary frequency standard

[Lux, Jim]

On 3/26/21 6:52 PM, Richard (Rick) Karlquist wrote:
> At HP, it was explained that a primary standard
> could be built on a desert island containing no
> frequency standards nor any GPS receivers, etc.
> and it would be guaranteed by design to meet its
> spec.  It could have adjustments, either operated
> by a technician or a computer controlled algorithm,
> but none of them consisted of "setting" the frequency
> to the correct value using a frequency counter, etc.
>
> It isn't based on accuracy.  The reduced performance
> HP 5062 is still primary, even though the 5061 is more
> accurate.  Similarly, the 5071 is still more accurate,
> but the 61 and 62 retain their primary status.
>
> ADEV is not an issue to qualify for primary status. 



Would a sundial  (or zenith meridian crossing sensor) be a primary 
standard for measurement of a solar day?