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Technical Information
How ClockWatch Works
The following is a summary of the steps ClockWatch performs when a time setting is made:
1. ClockWatch is started.
2. A time set is initiated by either:
User presses "Set Time" button
The alarm time set in the Once or Daily mode goes off.
The Auto mode calculation determines that the clock needs updating.
3. ClockWatch queries the timeserver specified by making a TCP/IP connection over the Internet or by dialing the timeserver directly..
4. The timeserver returns the exact standard time in NIST or Daytime format.
5. ClockWatch checks to see that the string returned is valid, if an NIST server it checks that the NIST server is healthy and that the time delay from the NIST is in a tolerable range, within 150 milliseconds.
6. ClockWatch converts standard time to local time and compares it to the internal system time on the computer.
7. If the time difference is within program thresholds the time adjustment is made. A summary of the setting is written to the log file (if enabled).
8. If the clocks are in sync or there was an error in communicating then the clock is not reset and the attempt is written to the log file.
9. Clock watch returns to the previous mode before the setting -- unless the mode was 'Once'.
The Role of the NIST
The National Institute of Standards and Technology (NIST, formerly the National Bureau of Standards) was established by an Act of Congress in 1901. Its role is "to assist industry in the development of technology ... needed to improve product quality, to modernize manufacturing processes, to ensure product reliability and to facilitate rapid commercialization of products based on new scientific discoveries."
As a non-regulatory agency of the U.S. Department of Commerce's Technology Administration, NIST's primary mission is to promote U.S. economic growth by working with industry to develop and apply technology, measurements, and standards.
The Time and Frequency Division is an operating unit of the Physics Laboratory of the National Institute of Standards and Technology (NIST). Located in Boulder, Colorado at the NIST Boulder Laboratories, the Time and Frequency Division:
Maintains the primary frequency standard for the United States.
Develops and operates standards of time and frequency.
Coordinates U. S. Time and Frequency standards with other world standards.
Provides time and frequency services for United States clientele.
Performs research in support of improved standards and services.
- Address:
National Institute of Standards and Technology
Time and Frequency Division
325 Broadway
Boulder, CO 80303
USA
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