
Chip Scale Atomic Clock - rdl
https://www.microsemi.com/product-directory/clocks-frequency-references/3824-chip-scale-atomic-clock-csac
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yourapostasy
Can a clock nerd please ELI5 how this chip differs from a frequency standard
like even the old Agilent (then Symmetricon) 5071A, not to speak of more
modern variants? For bog-standard businesses that want a on-prem physical
backup time standard for IT in case NTP and GPS are not available, would even
this chip be overkill?

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SAI_Peregrinus
It's cheap, small, and low-power. It's not a metrology standard like the
5071A. Something like this might be used as a more stable reference oscillator
for a radio transceiver. Cell towers typically use rubidium frequency
standards, this would likely be part of a package to replace those. They'll
also likely show up in high-end test equipment (oscilloscopes, spectrum
analyzers, etc).

Note that this thing doesn't provide date and time. It provides a 10MHz square
wave output and a 1 pulse per second output. You could use it to make a real
time clock, but that's not the intended purpose.

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maxmcd
$1,500 at release in 2011:
[http://www.insidegnss.com/node/2446](http://www.insidegnss.com/node/2446)

Not sure if this is an updated version or if there's another reason for this
to be relevant at the moment.

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Cyph0n
Looks like it's exactly the same product. Symmetricom, the company that
originally designed the CSAC, was acquired by Microsemi in 2013.

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qume
I've been trying to find out if using one of these in a GNSS receiver would
help with accuracy.

Anyone here know?

Clearly the clock on a receiver is well disciplined, but does that mean a
better oscillator like this wouldn't help?

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KaiserPro
I suspect compared to rtk its not really worth the hassle. GPS has been
specifically designed to not require a highly disciplined clock for the
receiver.

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easytiger
Yea but time degredation of TCOX etc after losing a signal is a thing

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rdl
Appears the dev kit is $1k at Digikey now.

I just saw someone mention it on FB and I didn't realize such a thing even
existed -- it's still expensive (5-10x a good TXCO), but pretty awesome.

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teraflop
Note that the dev kit just has a socket; you have to buy the actual clock
module separately.

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userbinator
The dev kit looks ridiculously overpriced, but this seems to be the norm even
with other electronics --- the "evaluation board", which is often not much
more than the device itself mounted on a PCB with some other cheap passives,
costs more than 10-100x the actual part.

In this case, however, I couldn't find anywhere selling the actual clock
module from a quick search, but there are mentions that it's $1500.

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rkangel
This has existed for a little while now, but doesn't appear to be available in
volumes greater than 'sample' (it is not uncommon for semi-conductor
manufacturers to jump the gun a lot on something being actually available).

I haven't tried to order one in a month or two though, so that may have
changed.

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matt2000
Is this the kind of thing that makes Google's Spanner database possible?

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0xbear
One of the things. They use GPS clocks as well.

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teraflop
Yeah, even if you have atomic clocks in every datacenter, you need an external
reference to synchronize them with each other.

(If you try to calculate the offsets between two clocks by using something
like NTP to measure round-trip times over the internet, you're implicitly
assuming that packet delays in both directions are symmetrical.)

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sharpercoder
How about syncing them at one physical place, moving while powered using a
battery, then hot-deploy in target datacenter?

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nightfly
Pretty sure relativity limits the usefulness of this.
[http://www.astronomy.ohio-
state.edu/~pogge/Ast162/Unit5/gps....](http://www.astronomy.ohio-
state.edu/~pogge/Ast162/Unit5/gps.html)

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userbinator
It's rather amazing that anyone with a couple of atomic clocks can see the
effects of relativity themselves:

[http://leapsecond.com/great2005/](http://leapsecond.com/great2005/)

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unwind
Very cool, didn't know these existed.

Still, it's quite the chip at 35 g mass (compare to an iPhone 8 at 148 g).
More like a module or something.

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self_awareness
What is Microsemi's relation to Microsoft?

Similar logo (well, at least colors are similar to Windows logo), similar
font, similar name.

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dugluak
Not sure why this was down voted, but this was my first thought too.

