[time-nuts] Frequency difference between LPRO-101 and HP 105B

Magnus Danielson magnus at rubidium.dyndns.org
Sat Dec 4 19:35:24 UTC 2010


On 12/04/2010 06:51 PM, ulmann at vaxman.de wrote:
>   Dear list members -
> being a proud owner of a LRPO-101 as well as a HP 105B and a TRACOR
> 527E Frequency Difference meter, I decided to compare these two
> oscillators with each other after some days of running them.
>   The attached plot (if this won't work, you can find it here online:
> http://fafner.dyndns.org/~ulmann/30_nov_2010_tracor_small.jpg) shows
> the output of the TRACOR 527E (frequency difference, sensitivity set
> to 10**11 - this corresponds to a multiplication factor of 10**4
> regarding the frequency difference) plotted with an old thermal
> plotter - this is just a qualitative plot but the amplitude difference
> between the minimum and maximum peaks corresponds to about +/- 1 parts
> in 10^-11.
>   I would like to hear your opinion about this - does this look
> reasonable to you? The inputs to the TRACOR were the 10 MHz output of
> the LPRO and the 1 MHz output of the HP 105B - both oscillators were
> running for a little bit more than three days without interruption.
>   All the best - Bernd. :-)

I notice that there is a repeated pattern (beyond the fact that the 
paper-trace has been scanned in overlapped fashion, which anyone viewing 
it should be aware of...) which I suspect is the due to the daily 
variations. Do notice how it has "quite" and "noisy" periods. In 
addition, there are similarities between these variations, possibly from 
the repeating pattern which the sun presents...

Time-marks in the data would help further analysis. So would the digital 
representation of values. It's booring cause I kind of like these old 
strips of papers, but it becomes a bit hard to use modern processing 
aids... which is possible since storage and processing power is now dirt 
cheap.

Cheers,
Magnus



More information about the time-nuts mailing list