What a marvelous range of answers this topic has produced. Perhaps it is the blind men and the elephant, again. Here are some of my blind observations:
1. Experience logging industrial process values taught me that it is most important that time be monotonically increasing. How would you plan to handle daylight savings time? Leap seconds? Is there a time when the device is certain to be idle? If so, you do not have an international business. What are the consequences of not having steadily increasing time, in your application? 2. There have been some wild guesses about the telco time error rate and direction of change. I have an AT&T Caller ID device which shows time of day and corrects it every time a call is received. This implies that the telco has a pretty good idea of the time of day, as well as frequency. Also have an AT&T 7720 cordless answering machine which is not set but gains 10-15 seconds per day. YATS32 tells me my computer gains 5.3 seconds per day. What we need is the expected drift rate of the telco device and the tolerance you have for absolute drift. I reset my answering machine every 3-6 months. I can always calibrate the difference by pressing the Clock button and hearing its current time. 3. We do not know exactly how the telco device time can be set, or if time can be read from the device. 4. If you elect an elegant solution (if one exists) who will pay for it? I assume this is a business application and not a hobby that we are talking about. Does this shed any light on the problem? Or are we blind men wearing coarse gloves. Regards, Bill Hawkins _______________________________________________ time-nuts mailing list [email protected] https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
