Hi James: Astronomical methods, such as sundials might deserve a place on the list.
73, Brooke Clarke, N6GCE -- w/Java http://www.PRC68.com w/o Java http://www.pacificsites.com/~brooke/PRC68COM.shtml http://www.precisionclock.com >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. > > > _______________________________________________ time-nuts mailing list [email protected] https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
