Time and Frequency Measurement

I've always been interested in the technology used to measure things very accurately, and as a ham radio operator, my focus rapidly became measuring frequency, and its inverse, time (or is it the other way around?) to the Nth degree. In particular, I'm interested in how radio can be used to make precise time and frequency information available to end users. This page has some details of my current experiments.

If you're interested in what you find here, you might also want to check out my Geekworks pages which cover some of my other (often related to time & frequency measurement) projects.

John's GeekBlog serves as my online logbook; mostly it's going to be pretty boring stuff, but I store various phase plots, charts, screen dumps, etc. there, so you may want to see if anything catches your eye.

I recently reorganized the web site a little, and am migrating the technical pages into www.febo.com/pages. This will include not only purely time and frequency related materials, but also stuff from my Geekworks pages as well; there's a lot of overlap between the two topics. Over time, almost all technical content will migrate to www.febo.com/pages but the /time-freq and Geekworks home pages will remain to provide an organizational framework.

Going to www.febo.com/pages will show you a list of directories; clicking on one will take you to its contents. Some of the directories will be full-blown web pages, others may contain just some pictures or plots.

I have written a bunch of scripts to automagically generate and update charts from my data logging experiments. You can see the results:

I've written some programs that do the work of generating these plots. You can learn about them, and grab them for yourself, at www.febo.com/time-freq/tools.

There are three principal methods used to disseminate time and frequency information from national standards institutes to end users. They are: (a) VLF radio stations like WWVB; (b) the LORAN-C navigation system; and (c) GPS satellites (there are numerous other systems that have been used, but they are either obsolete, very specialized, or of relatively low performance). I've been experimenting with all three, and there's a page here for each:

In addition I've create a bunch of other pages related to other aspects of precise time and frequency measurement:

Here are links to some other sites of interest to time-nuts.