[time-nuts] noise of a 5370

[Said Jackson]

Hi,

The average will approach 0.0 as the number of samples is increased, but not the standard deviation.. The value displayed by their unit is standard deviation.

Bye,
Said

Sent from my iPad

On Mar 12, 2011, at 8:47, mikes at flatsurface.com (Mike S) wrote:

> At 10:45 AM 3/12/2011, Jean-Louis Noel wrote...
>> Yes, I saw that!
>> But, where is the logical when your display starts at 100fS?
> 
> A mean (average) measurement improves things by the square root of the number of measurements, if I'm not mistaken. So, if you measure 100,000 times, then a 35 ps jitter is reduced to ~ 110 fs ( 35 ps / sqrt(100000) = 35 ps / ~316 = ~110 ps). Using HPIB, you can do measurements up to 2^24-1 = 16777215 times, so 35/4096 = ~9 fs.
> 
> There are other error sources which make the actual accuracy worse than that, though. For instance, HP gives a +- 1 ns "Sytematic error" for TI measurement, regardless of the number of measurements. They say it's typical 300 ps and can be reduced to 30 ps. I'm not sure if that is random or what consistency it has between different measurements. It may only effect absolute accuracy, not relative accuracy when comparing measurements.
> 
> Someone will tell me if I'm wrong. 
> 
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