[time-nuts] T.I. questions

[Bill Hawkins]

Referring to a 1952 manual on servo systems, jitter seems to be noise
in the system, while dither is intentionally introduced to get a servo
through its dead space (usually caused by static friction).

The dead space in a counter is the interval between least significant
integers.
Thus the amplitude of the dither is the size of that dead space at a
frequency
that will be lost in the average.

I can see how this would work for a servo system, but how can a counter
display
more resolution than its least significant digit?

Bill Hawkins
 

-----Original Message-----
From: time-nuts [mailto:time-nuts-bounces at febo.com] On Behalf Of Magnus
Danielson
Sent: Wednesday, February 04, 2015 5:41 PM
To: time-nuts at febo.com
Cc: magnus at rubidium.se
Subject: Re: [time-nuts] T.I. questions

Joe,

The single-shot resolution of the Option 040 series input is 10 ns.
The T.I. interval option adds jitter to make the averaging useful.

If your PPS was instead a burst or a clock, comparing it to your clock 
would make more sense and you could use that higher resolution.

If I had a GPIB interface for my 5328A, I would play around with it
more.

I think I recall a 10 ps resolution being achievable according to fancy 
specs, with averaging to it's max.

Cheers,
Magnus

On 02/04/2015 09:58 PM, Joseph Gray wrote:
> Sorry for the simple questions. Old hands can simply ignore this
> message if it bothers you.
>
> I have an HP 5328A that I have pieced together from broken units. As
> soon as I make a ribbon cable for the GPIB card, I want to use it for
> T.I. measurements. I know it isn't nearly as good as a 5370, but it is
> what I have at the moment.
>
> The manual states that the Universal module adds dithering to the
> multiplied 100 MHz internal reference. If I use a GPSDO as an external
> reference, will this multiplying/dithering allow me to use the same
> GPSDO (divided down to PPS) on either the START or STOP inputs? If
> not, then how about using a different GPSDO as the external reference?
> Or even an FE5680A rubidium?
>
> If I read the specs correctly, using T.I. averaging on the 5328A, a
> 1000 s average should get me 100 ps resolution? With this particular
> instrument, what is the best, useful resolution I can expect?
>
> Joe Gray
> W5JG
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