Yes, most oscillators have that sort of "steep slope down" to "flat part" to "slope up"
In some sense, they all have the same origin - the low time (close in) are usually influenced by the "resonator"'s short term performance (Q if you will, in some cases)
The flat part is driven by the noise in the system (in the canonical amplifier with a filter model, the filter is noiseless, the amplifier sets the floor).
The long time is more of a "stability over time" aspect - aging, etc. So for atomic standards, the frequency is an intrinsic property of the atoms, so they don't have aging and drift (although there are a lot other things that can affect it), but for quartz oscillators, they DO age.
(And, of course environmental effects.. who among us has not seen fluctuations with 20-60 minutes or 24 hour periods from HVAC and room temperatures)
So all those quartz oscillators, since they have the same basic physics, will have the same slope on the short time end. The absolute values and the break points depend on the physical properties of the particular resonator, how it's driven, held, etc. (I don't know if other resonators, like sapphire rings, have the same slope.. I think they do)
And for a lot of sources that combine things (a disciplined quartz oscillator, for instance) will have a hybrid curve.
On Sun, 2 Feb 2025 07:59:32 +1100, mcleannb--- via time-nuts time-nuts@lists.febo.com wrote:
Hi Jim,
Do you have any explanation as to why they all follow (roughly) the same
curve?
Nic
VK2KXN
Newcastle Australia.
-----Original Message-----
From: AC0XU (Jim) via time-nuts
Sent: Thursday, 30 January 2025 11:45 PM
To: time-nuts@lists.febo.com
Cc: AC0XU (Jim)
Subject: [time-nuts] Best quartz oscillator MADEV
Just for fun, these are the best free-running quartz oscillators from my
lab. FTS1150A1 and OSA8600A are BVAs. The HSO14 oscillators are Rakon's lab
oscillators. The others are standard FTS oscillators. This ensemble analysis
method results in large uncertainties for the best 1 or 2 oscillators at any
given time constant.
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Yes, most oscillators have that sort of "steep slope down" to "flat part" to "slope up"
In some sense, they all have the same origin - the low time (close in) are usually influenced by the "resonator"'s short term performance (Q if you will, in some cases)
The flat part is driven by the noise in the system (in the canonical amplifier with a filter model, the filter is noiseless, the amplifier sets the floor).
The long time is more of a "stability over time" aspect - aging, etc. So for atomic standards, the frequency is an intrinsic property of the atoms, so they don't have aging and drift (although there are a lot other things that can affect it), but for quartz oscillators, they DO age.
(And, of course environmental effects.. who among us has not seen fluctuations with 20-60 minutes or 24 hour periods from HVAC and room temperatures)
So all those quartz oscillators, since they have the same basic physics, will have the same slope on the short time end. The absolute values and the break points depend on the physical properties of the particular resonator, how it's driven, held, etc. (I don't know if other resonators, like sapphire rings, have the same slope.. I think they do)
And for a lot of sources that combine things (a disciplined quartz oscillator, for instance) will have a hybrid curve.
On Sun, 2 Feb 2025 07:59:32 +1100, mcleannb--- via time-nuts <time-nuts@lists.febo.com> wrote:
Hi Jim,
Do you have any explanation as to why they all follow (roughly) the same
curve?
Nic
VK2KXN
Newcastle Australia.
-----Original Message-----
From: AC0XU (Jim) via time-nuts
Sent: Thursday, 30 January 2025 11:45 PM
To: time-nuts@lists.febo.com
Cc: AC0XU (Jim)
Subject: [time-nuts] Best quartz oscillator MADEV
Just for fun, these are the best free-running quartz oscillators from my
lab. FTS1150A1 and OSA8600A are BVAs. The HSO14 oscillators are Rakon's lab
oscillators. The others are standard FTS oscillators. This ensemble analysis
method results in large uncertainties for the best 1 or 2 oscillators at any
given time constant.
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