You can automatically or manually synchronize your computer clock with one of the internet time servers using this utility. This is very useful as many computer clocks accumulate significant error over a period of just a few days and some have significant errors within a few hours. The Radio-Sky SNTP Clock Client can set your computer time to within a few milliseconds. This is a significant improvement over the clock tool available in version 1 editions of Radio-SkyPipe, which typically only was accurate to about 1 second.
Getting the Time
The Atomic Clock utility is available under the Tools item of the main menu. After starting try pressing the Get Time button. If you are on line and you do not have the timekeeping blocked by a firewall or router, you should soon see the yellow text field contain several lines of data similar to the picture above. You need not worry about what all of the fields mean. Most refer to the characteristics of the time server from which you are getting the time update and on the times that data was sent between your computer and the time server. The most important line is the last one, the Suggested Correction. Typically if this value is less than +/- 0.010 (one 1/100th) seconds, the timing is considered good. If you have a good internet connection and a fast computer you may be able to get the accuracy to perhaps +/-0.005 seconds.
Adjusting the Time
To adjust your computer system clock manually just press the Adjust Clock button. Again notice the suggested correction. If it is small then all is well, but occasionally you will get larger suggested correction. Adjust the Clock several times and you should see the Suggested Correction settle down to a small range of values. When the clock utility automatically adjusts the clock it also takes several readings and selects the optimal choice for correction. Select the Auto Adjust check box to make the utility automatically adjust your clock based on the time period you select from the drop-down list below the check box. Note it is not a good thing to update your clock more than necessary to keep you within the correction accuracy of the utility. If you correct more often than needed you are introducing a "jitter" in your system clock that itself produces errors in timing.
There are a large number of time servers run by universities, government institutions, and others spread around the world. It is even possible to run your own time server on your local area network. GPS disciplined clocks have made this an attractive proposition for some. By default your time server is NTP Pool but you can select from any of many servers on the drop-down list at the bottom of the utility window. Sometimes picking a server close to your location can lead to better accuracy. If you need to add a time server to the list you can do so manually by editing the SNTPtimeserverlist.txt file in your Radio-SkyPipe II directory. The format is simple, just the name of the server followed by a URL, for example:
time-a.nist.gov NIST Gaithersburg Maryland
time-b.nist.gov NIST Gaithersburg Maryland
time-a.timefreq.bldrdoc.gov NIST Boulder Colorado
time-b.timefreq.bldrdoc.gov NIST Boulder Colorado
Under the Options menu at the top of the clock utility you will find:
Number of Retrievals - This is the number of times the time server is queried each time the program wants to find out the time. The reason it is usually best to query the server several times is to remove errors that might arise in the process. You do not want to set this number too high as some time servers will "ban" a client that hits it too often. 5 seems to be a good number for internet retrievals but you might set it lower if you have a timer server on your LAN or if you experience frequent "glitch" adjustments that do not seem warranted.
Max Correction (ms) - During automatic adjustments, suggested corrections greater than this number of milliseconds will be ignored. This can prevent errors caused by glitches.
Min Correction (ms) - During automatic adjustments, suggested corrections less than this number of milliseconds will be ignored. This reduces jitter in the system time caused by making corrections that are not warranted, that is, corrections that are less than the inherent error of the utility and SNTP process.
Program Priority - Select the level of program priority given to the utility by Windows. Caution: setting the program to real time may stall your computer!
Log - Create a log of suggested corrections. This is a simple text file of the format HH:MM:SS (tab) Suggested Correction Value (CRLF). For example:
This file can be imported into Radio-SkyPipe II using the new Import Text utility. If the Radio-Sky SNTP Clock Client cannot retrieve the time then no item will be logged for that scheduled time retrieval.
View Log - Loads the log file into notepad.
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