On 03/01/2013 06:05 PM, Mark Spencer wrote:
Greetings:
As my plan to buy a time pod is on hold for now (: I'm revisiting my
HP5370B's. I'm debating if I should embark on a re alignment project or not.
My better HP5370B's seem to have a practical resolution of 40 ps or so with
typical signals (ie. comparing and ocxo to a gpsdo.) Noise floor tests with
idealized signal levels typically produce results in the mid 20 ps range.)
Given the inherent 20 ps single shot resolution of the HP5370B plus what ever
error is introduced by the two trigger circuits I'm wondering how much
improvement I might get from a re alignment. I do have an 8082 pulse
generator.
At this point I'm thinking a re alignment is unlikely to buy me much.
Any comments would be welcome.
What is the slope of the signal you measure?
You could be slew-rate limited in your measurements, in which case you
might want to square it up.
Try damping the signal by 6 dB, and then as you compare the RMS noise,
you should be able to separate out how much is due to slew-rate and how
much is due to internal trigger and measurement noise.
It's a trivial enough test to do.
Cheers,
Magnus
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