Time: Difference between revisions
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[http://en.wikipedia.org/wiki/Time Wikipedia article] | [http://en.wikipedia.org/wiki/Time Wikipedia article] | ||
Related wiki pages [[Time Beacons]], [[Modes]] | |||
==What are GMT, UTC and Zulu?== | ==What are GMT, UTC and Zulu?== | ||
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* [http://www.timeanddate.com/library/abbreviations/timezones/ Timezone abbreviations] | * [http://www.timeanddate.com/library/abbreviations/timezones/ Timezone abbreviations] | ||
* [http://www.navysite.de/what/zulu.htm What does zulu time mean?] | |||
Revision as of 17:25, 10 November 2010
Related wiki pages Time Beacons, Modes
What are GMT, UTC and Zulu?
GMT (Greenwich Mean Time) was introduced when the concepts of longitude and latitude cane to be used for sea navigation. It is the line of longitude - passing though Greenwich Great Britain that all times around the world were compared to. This longitude line is known as the Prime Meridian
UTC (Coordinated Universal Time) was introduced when the accuracy of clocks improved to the extent that variations in the rotation of the earth caused measurable errors in time calculations. UTC now replaces the GMT
Zulu the letter Z in the phonetic alphabet. The time designation used in aviation and defence.
Time in Amateur Radio
Various digital modes are very dependent on accurate time measurements:
- WSPR requires a time accuracy within 1 second of UTC. WSPR operates in 2 minute time slots with computer links to effect reception reports.
- JT65HF also requires high accuracy time coordination