[time-nuts] List of time synchronization hardware and software

Brooke Clarke brooke at pacific.net
Mon Jan 16 18:14:44 EST 2006

Hi James:

Astronomical methods, such as sundials might deserve a place on the list.


Brooke Clarke, N6GCE

w/Java http://www.PRC68.com
w/o Java http://www.pacificsites.com/~brooke/PRC68COM.shtml

>A clock consists of a frequency standard plus a counter.  Accordingly, a
>list of "hardware" that provides time would include:
>A. Mechanical wrist watches and mechanical clocks. For these, the 
>frequency standard might be a pendulum, and the the counter might be an 
>arrangement of gears to count seconds, minutes, houts, etc., and display 
>them on mechanical dials for the user to observe.
>B. Electrically powered wristwatches and clocks that include tuning 
>forks as their frequency standard.
>C. Electrically powered wristwatches and clocks that include crystal 
>oscillators as their frequency standards.  Most retail clocks and 
>wristwatches fall into this category.
>D. Wristwatches and clocks that include crystal oscillators that are 
>"synchronized" from time to time with radio receivers. These include, 
>for example:
>D.1. "Atomic Time" and other brands of wristwatches and clocks that 
>synchronize their dials (counters) against the 60 kHz LF signal from 
>WWVB near Ft. Collins, Colorado.
>D.2. Similar products that synchronize their dials against other LF 
>signals from other LF (low frequency) or MF (medium frequency) time 
>signal stations such as MSF (Rughy, United Kingdom, 60 kHz); TDF 
>(Allouis, France, 162 kHz); HBG (Prangins, Switzerland, 75 kHz); etc.
>D.3. Similar products with HF radio receivers for such time and 
>frequency stations as WWV (Colorado, USA: 2.5 MHz, 5.0 MHz,  10.0 MHz, 
>15.0 MHz, 20.0 MHz), WWVH (Hawaii, USA: 5.0 MHz, 10.0 MHz, 15.0 MHz), 
>CHU (Ontario, Canada: 3330 kHz, 7335 kHz, 14670 kHz), BPM (Shaanxi, 
>China: 2.5 MHz, 5.0 MHz, 10.0 MHz, 15.0 MHz), etc.
>D.4. Similar products that both "synchronize" their counters and 
>"syntonize" their frequency references against standard time and 
>frequency broadcasts.
>D.5 Similar products that either "synchronize" their counters (or both 
>"synchronize" their counters and  "syntonize" their frequency standards) 
>against signals received from GPS satellites.  Almost any GPS receiver 
>will display time of day.  (Many will not, however, display it in a 
>"timely" manner!)  GPS receivers that are to be used for precise timing 
>purposes should provide a 1 Hz (1 pulse per second) output.  Some of the 
>better ones will provide 5 Hz or 10 Hz outputs, if they provide fixes 5 
>or 10 times per second.
>As Rob Kimberly said, a list of hardware timing devices could be rather 
>lengthy! It would help if you could be more specific, and perhaps rule 
>out such devices as mechanical clocks and chronometers.

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