[time-nuts] Cheap jitter measurements

[Hal Murray]

gem at rellim.com said:
> With care I can measure GPS jitter on a RasPi to a bit over 300 nano sec
> resolution.  That is the smallest increment of the RasPi 3B clock with a
> 64-bit kernel.  That is clearly not time-nuts accuracy.

> What would you guys suggest as the cheapest way to see jitter down to around
> 1 nano second?   

What do you mean by "jitter" and what do you really want to do?

Jitter usually needs a reference.  Do you have one?


> I'm thinking maybe something like a rubidium standard (FE-5680A) and a
> TICC-TAPR?  But that would put me out around $400. 

Do you have a scope?

The Rigol DS1102E is/was quite popular and is good for close to a ns.  I got 
mine several years ago for $400.  Looks like the going price is closer to 
$300 now.  It's got a USB port.  You can read the data and decode it in 
software.

They make lots of similar scopes.  The middle 2 digits are the bandwidth: 5=>
50MHz, 10=>100MHz.  The last digit is the number of channels.)

The chip in the BeagleBone series boards has extra CPUs that help with things 
like this.  I don't know how fast they go.  I haven't seen 64 bit versions or 
a lot of software activity.

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