[time-nuts] Measuring GPS noise floor (sort of)

Bob Camp lists at rtty.us
Sun Dec 2 22:51:26 UTC 2012


The GPSDO vs GPSDO should be pounding pretty hard against the 1.0 x 10^-14 line out around a day. You should see a bit of a hump at 24 sidereal hours. 


On Dec 2, 2012, at 5:37 PM, Mark Spencer <mspencer12345 at yahoo.ca> wrote:

> I'm wondering how useful it is to compare two different GPS receivers to a single Rb to get a sense of the GPS noise floor.   I've been collecting some data for the last week or so seem be making some headway with this.
> Not having a cesium or an Hmaser I elected to compare two different GPSDO's to a single Rb and then assuming the data seemed sane, I thought I would then compute the Adev between the two GPSDO's.   My assumption is that by comparing the two GPSDO's to the Rb it should be possible to detect when one GPSDO is mis behaving or possibly when the Rb mis behaves.  So far other than a bit of a glitch at the start of the process things seem to be proceeding as I expected.   I hope to collect another two weeks or so of data if all goes according to plan.
> I'm really only interested in the longer term numbers and I wouldn't put to much trust in the shorter term results.
> Comments would be welcome especially if there is a fundamental flaw with this process.   
> Looking at the data gave me something to do this afternoon during some down time on a business trip (:  I reazlize this approach is probably not how the pros would do this.
> Regards Mark Spencer
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