Hi Richard,
the frequency of pulsars has a slow deccay, so they can't be good
standards, in reality they are worse than our terrestrial atomic
clocks...and we are not able to mesure better as 10E-17 s.
Cordiales 73
Alain F4GBC
----- Original Message -----
From: "Richard (Rick) Karlquist" <[email protected]>
To: "Discussion of precise time and frequency measurement"
<[email protected]>
Sent: Friday, March 05, 2010 3:39 PM
Subject: Re: [time-nuts] nubie querie
Don Collie jnr wrote:
I`m not sure that questions like these is welcome on this list, but here
goes anyway : 1/ What are the the 10 sources of the most constant
[invariant] frequencies known to man, in order of decreacing constancy?
Four immediately come to mind.
I vaguely remember reading that pulsars have some fantastic
stability like 1E-20. I don't remember how they established
this.
2/ What is the mechanism in an oscillator, that is responsible for phase
noise? [In only one sentence please]
Thermal (Johnson) noise in the resonator and thermal and shot noise in the
active device.
If this is known, then it becomes easier to design low phase noise
oscillators.
Perhaps, but just knowing the mechanism doesn't tell you that the
phase noise is inversely proportional to loaded Q, which you would
also need to know to optimize phase noise.
I hope you enjoy these questions,.................................Don.
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