Monday, May 28, 2018

Time Is Precious

Earlier this month I was privileged to be included on a tour of the time and frequency facilities at the Boulder Colorado laboratories of the National Institute of Standards and Technology (NIST). I got to walk right up to the F-2 cesium fountain atomic clock, the standard frequency reference for the entire United States.

NIST F-2 Cesium Fountain Clock

I always thought the F-2 ran all the time. Fortunately that's not true, or else we might not have been able to see it. NIST fires it up periodically to calibrate an ensemble of commercial atomic clocks, which do run all the time, and which we didn't get to see.

I also got to see a couple of the prototypes of the chip-scale atomic clock (CSAC) developed as a result of NIST and DARPA research projects.

Prototype Chip Scale Atomic Clock

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I used a commercialized version of this same device in the stratum-0 NTP server that I built.

So it only seemed appropriate this morning that I take a little jaunt up to see the WWV (short-wave) and WWVB (long-wave) transmitter towers just north of Fort Collins Colorado.

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This is from where a time code is transmitted to an estimated fifty million radio clocks, including the WWVB radio clock that I built, in the continental United States. The time code is synchronized to a cesium atomic clock on site, which in turn is synchronized to the NIST master atomic clocks in Boulder Colorado.

Tuesday, May 22, 2018

An Easy Home-Brew Stratum-1 GPS-Disciplined NTP Server

This here is my latest, and simplest, home brew, GPS-disciplined, NTP server: "Candleclock" a.k.a. "O-4". If you wanted to leave out the battery-backed-up real-time clock and the LCD display, which are really just convenience features, you could put one of these together on your lunch break out of a Raspberry Pi (here, a 3 B+)

Candleclock

a NaviSys GR-701W USB GPS receiver which supports 1PPS

NaviSys Technology GR-701W

and some open source software. (The guy that sells the GR-701W on Etsy is the project manager of the NTPsec open source project!) The completely optional beautiful clear plastic stand is a leaflet holder from the local office supply store.