[time-nuts] MT3339 PA6H and Racal Dana GPIB, update

Bob Camp lists at rtty.us
Wed Dec 12 20:55:51 UTC 2012


Ok, so the data is already decimated and it does show a 20 hour period.

The way I'm reading things - the pps's start out at zero offset on the left
side (yellow line at about sample 350). They still are at roughly zero
offset on the right side (at about sample 17045). Total peak to peak in the
yellow line is 0.5 ns. Total peak to peak in the red line is 1.4 ns. One ns
over 20 hours would be 1.4x10^-14.

So back to the original question - was drift in the pps removed before the
graph was done? 


-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
Behalf Of Fabio Eboli
Sent: Wednesday, December 12, 2012 3:42 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] MT3339 PA6H and Racal Dana GPIB, update

Bob Camp <lists at rtty.us> ha scritto:

> Hi
> 20 hours should be 20*60*60 = 72000 samples. The graphs appear to show
> 17,000 samples.

Hello Bob,
unfortunately I'm not logging all the pps
samples, I'm picking one sample every about
4 pulses, because I'm triggering the counter
and waiting 4s before reading the result.
So these are not consecutive pps periods.

See my previous message of 11-Dec 23:36.

Here I have two main problems I will try to
solve for now:
- I have to understand how to sync the logging
script to the counter, so I can read all the values.
- The counter cannot read every pps in period
mode, but one every two, so I will try
to use the start-stop method, since this
FE5680 frequency is fortunately very close
to the mark.

> If the results do cover a 20 hour period and do not have drift removed,
> that's a good FE5680. 1.4x10^-14 is an amazing number for one of those.
> Bob

Sorry, here I don't follow you, maybe my graph
is misleading, or I'm not understanding, but I
see that the FE5680 frequency seem wrong by 3x10^-10
and goes up and down by 3 to 4x10^-10, it's not
thermoregulated but simply mounted on an aluminium
plate, into a room not thermoregulated.


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