[time-nuts] Reference input on HP counters
paulswedb at gmail.com
Sun Jan 7 10:46:38 EST 2018
It depends on the unit and age. There are not rules of thumb from my
Some of the approaches in HP as an example
Have switches and demand a specific frequency and level.
Some lock an internal reference to any multiple of a reference freq like 5
or 10 MHz.
Some are direct some are phased lock.
I actually look at each piece of HP gear and see whats going on.
Lazy can get you in trouble as I learned.
On Sun, Jan 7, 2018 at 10:21 AM, Jerry Hancock <jerry at hanler.com> wrote:
> I’m being a little lazy as I can check the schematics, but in the general
> case, do HP counters, frequency generators, etc, switch to the external
> reference when one is available or discipline the internal oscillator? Are
> there brands of test equipment that generally discipline vs switch?
> Third question, again generally, when you discipline an oscillator, what
> impact does this have on the oscillator's phase noise? I assume this third
> question depends on the discipline loop (if I’m using the correct term).
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