[time-nuts] Agilent 53220A and TimeLab

[John Miles]

Hi, Timothy --
 
> I've had an Agilent 53220A for some time, and recently discovered the
> wonderful TimeLab software, but I've hit a bit of a snag trying to run some
> ADEV measurements on a Rb clock.  The problem is that the graph doesn't
> line up with the amount of data TimeLab says is collected. I ran an
> acquisition for 100 seconds, but according to the chart it only shows data
> collected for 20 seconds....

See page 31-32 of the manual (http://www.miles.io/TimePod_5330A_user_manual.pdf).  I think you'll find it anticipates that very same question. :)

> On a side note, I was disappointed to find out that I missed the boat on
> the semi-affordable TimePod. Is there anything remotely in the price rang
> (sub 5K) that can do stability AND phase noise measurements? It seems like
> the Wavecrest DST "might" be able to, but from what I read in the time-nuts
> archive I wasn't able to get a clear picture.... there's an app note
> floating around about making phase noise measurements with it, but
> nothing
> solid.

The Microsemi 3120A's price has come down a bit over time, so I'd suggest checking with them to see what the current pricing is like.  (Obligatory disclaimer: I have no current financial/professional involvement with the 3120A.)  I suspect it's still well north of $5K, depending on options, but I know they've stepped back from the initial prices they were quoting.

I'd encourage you to build something, though, given that you're not doing this stuff for your day job.  There's a reasonable amount of literature out there on both quadrature PLLs for PN measurement and the related tight-PLL topology that's well-suited to stability measurement.  They can both return very high-quality results for very little money, if you're willing to put in the necessary "sweat equity."  This approach is much more educational than simply throwing money at hardware, and (speaking from experience) more fun as well.

-- john, KE5FX
Miles Design LLC