[time-nuts] 5370 processor boards available

[Bob Camp]

Hi

Well “so far they look the same” is a pretty good answer to the question. Running emulated code, that’s the outcome that I would expect. Of course one always has to be careful when you find the expected result :)

To me the next layer here is to see if the basic accuracy of the device can be improved in software. My guess is that’s not going to happen, but one should look into it.  If that’s a dead end, there’s always putting a CNT-90 like frequency estimator into the code.

Bob

On Feb 28, 2014, at 2:16 AM, Poul-Henning Kamp <phk at phk.freebsd.dk> wrote:

> In message <7984E000-057C-4790-9D20-E4DAC1F6008F at rtty.us>, Bob Camp writes:
> 
>> Is there any performance data on how the card does with a 5370A and / or a
>> 5370B compared to the original CPU on the exact same box? Put another way -
>> does the counter get better or worse with the new card? I realize that an 
>> A will do some things with B firmware, that=92s not the question I'm asking.
>> I'm looking for A to A or B to B timing data.
> 
> I have spent most of my time trying to answer exactly that question
> and I have not been able to devise any experiment that shows a
> difference in noiselevels with a credible statistical uncertainty.
> 
> Interestingly, it is pretty evident from my experiments that the
> phase-noise of whatever EXT CLK source I use is the main cause of
> one-shot noise, so if anybody happens to have a *really* clean
> 10MHz and a 5370, it would be interesting to hear how low it
> can go.
> 
> -- 
> Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
> phk at FreeBSD.ORG         | TCP/IP since RFC 956
> FreeBSD committer       | BSD since 4.3-tahoe    
> Never attribute to malice what can adequately be explained by incompetence.