[time-nuts] Checking accuracy of Rubidium standards
Jeffrey Pawlan
jpawlan at pawlan.com
Sat Nov 8 18:40:52 UTC 2008
On Sat, 8 Nov 2008, Randy wrote:
> I was wondering if it is worthwhile or even feasible to compare an LPRO
> Rubidium standard against a Z3801. Since their frequencies are probably
> going to be extremely close anyway it would seem some special
> method/equipment would be required for high precision. Suggestions?
>
>
> Randy, W7HR
> Port Orchard, WA
The best way would be to compare the highest possible frequencies you can
generate with these two sources. I use two 10GHz sources that are each phase
locked to an external 10MHz reference. Then the 10GHz outputs can be compared
using either of these easy methods:
1) look at the DC/IF output of a microwave mixer where the LO and RF ports are
driven by the two 10GHz sources. Don't overdrive the RF input to a level that
can burn out your mixer.
2) use a good microwave frequency counter to read one of the 10GHz outputs while
driving the counter's 10MHz ext ref input with the 10MHz from the other 10MHz
source. This is very fast but will only give you accuracy readings that are a
function of the resolution of the counter plus the bounce of the last digit
owing to sampling and triggering.
3) if you have access to a lab with one or two microwave synthesized signal
generators, then you can apply the 10MHz sources to the ext ref inputs of each
of these signal generators and then proceed as in 1) or 2)
I have done comparison at 26GHz this way so I have a bit more resolution.
73,
Jeffrey Pawlan WA6KBL
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