Chip Scale Atomic Clock

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.

I'm not a clock pro or anything, but it looks like this cites stability numbers around 1e-10 or 1e-11. 5071A says things like 1e-14, but I don't know if it's apples-to-apples. For "portable" applications, NASA's working on the Deep Space Atomic Clock (DSAC) for easier/better space navigation. DSAC is cited as having 1 microsecond per decade stability, or about 3e-15.

While it might be orders of magnitude better than a stabilized quartz oscillator, it looks orders of magnitude away from traditional atomic clocks.

A CSAC is a c(a)esium standard, but it's not a primary cesium standard. A primary standard is required to deliver its rated accuracy without calibration, but the CSAC is more like a rubidium gas cell than a traditional cesium-beam standard. It's very stable relative to most clocks, but it still drifts under the influence of temperature, aging, barometric pressure, and who knows what else.

When you ask "what time is it?", the answer ultimately comes down to an ensemble of cesium-beam clocks, mostly but not exclusively HP/Agilent/Symmetricom/Microsemi 5071As. A 5071A will be about 10x as stable as a CSAC over intervals from seconds to days.

The important thing here is 'chip scale'. This is a device that can be integrated into relatively small packages, enabling a number of use cases.

To give an example - direction finding of the source of a radio signal using multiple drones. This requires the drones to have extremely good time synchronisation so that the time of arrival at each of them can be compared. With a CS atomic package that can be a trivial exercise, without it you need to rely on an external timing reference of some form (e.g. GPS).

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

I'm seeing $5300 at Mouser and Digikey, but none in stock yet.

http://www.mouser.com/ProductDetail/Microsemi/090-02984-001/...

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.

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

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

I wonder how well Google's database would work in an interplanetary setting, where due to high relative velocities the property of simultaneity does not exist.

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