Off topic, but I heard tonight that WWV is going off the air at the end of
this month.
On Sunday, October 14, 2018, 9:24:51 PM PDT, Tom Van Baak
<[email protected]> wrote:
> This is just a free running PRS10 wired to a TAPR TICC, I thought that I
> would
> run some stand alone tests before I brought my GPSDO in line too.
Ok, good idea to do a stand alone test. The plateau, though, is interesting and
I wouldn't quite have expected that in a 1PPS vs 10 MHz self-test. Let's look
into that.
> The PRS10 is the source for the 10MHz as well as reading the 1PPS output from
> it.
Ah, ok, that would explain the unusually low MDEV beyond tau 1000. Since you're
essentially comparing the oscillator with itself you would expect the MDEV
numbers to be [far] lower than the performance of an actual frequency standard.
Once you fire up your GPSDO and use that as a reference, your PRS10 ADEV/MDEV
numbers will look more appropriate.
/tvb
----- Original Message -----
From: Chris Burford
To: 'Tom Van Baak' ; 'Discussion of precise time and frequency measurement' ;
'Discussion of precise time and frequency measurement'
Sent: Sunday, October 14, 2018 8:07 PM
Subject: Re: [time-nuts] PRS10 MDEV
Tom,
This is just a free running PRS10 wired to a TAPR TICC, I thought that I would
run some stand alone tests before I brought my GPSDO in line too. The PRS10 is
the source for the 10MHz as well as reading the 1PPS output from it.
Chris
-----------------------------------------
From: "Tom Van Baak"
To: "Discussion of precise time and frequency measurement"
Cc:
Sent: Sunday October 14 2018 9:45:46PM
Subject: Re: [time-nuts] PRS10 MDEV
Chris,
Thanks for sharing the plot.
What instrument are you using to make the measurements? And what frequency
reference is being used? Is this a free-running PRS10, or is it locked to GPSDO
with some time constant?
Is that same GPSDO being used as a reference for your measurements? The plateau
looks very much like GPSDO behavior and the slide into e-14 and e-15 territory
looks like you're measuring a PLL.
/tvb
----- Original Message -----
From: "Chris Burford" <[email protected]>
To: <[email protected]>
Sent: Sunday, October 14, 2018 7:07 PM
Subject: [time-nuts] PRS10 MDEV
> Hello All,
> I've collected several data sets over the last few days from my RFS
> and I'm puzzled by what I'm seeing. A link to the plot is here:
> https://drive.google.com/open?id=10Kk8Cqx7es0SXf2H5AldiQkBo8nIfNMT
/> > I'm looking at the averaging periods from about 100 thru 400 tau and
> noticed a "plateau" or a brief level off period and then it proceeds
> down and right again. Is this flat area a function of the averaging
> algorithms for the MDEV or is it something else?
> I have spent considerable time in reading "Techniques for Frequency
> Stability Analysis" by W.J. Riley and a host of other publications
> (NIST, etc) in preparation for this. I would enjoy hearing from any
> readers that may have some insight as to what I'm seeing and or
> possible causes.
> Thanks for reading.
> Chris
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