[time-nuts] Did a member of time-nuts buy this?-

[Magnus Danielson]

Bob,

On 12/11/2014 02:25 AM, Bob Camp wrote:
> Hi
>
>> On Dec 10, 2014, at 8:02 PM, Mike Monett <timenuts at binsamp.e4ward.com> wrote:

>> OK, so I figure out how to do this. How do I tell if this is making the
>> gpsdo more accurate? In other words, how do I get the ADEV without having
>> an H-Maser?
>
> You get a Cs (or other atomic standard) or you compare several different GPSDO’s against each other. The preference would be for groups of three so you can rule out ones that are not doing what they should.

GPS receivers can have considerable common mode effects, which won't 
show up in the three-cornered hat setup. You can work with a rubidium 
clock and a crystal clock if you don't have a cesium standing by.

> You also need the measurement gear to resolve frequency down in the 1x10^-13 range. A normal counter will not do that.

Indeed.

Cheers,
Magnus