(as it may apply to amateur radio operators)
This page became larger than I expected, so here is an index to its sections.
Amateur Radio operators have a large need to keep their clocks synchronized. The reason for this is for the proper logging of communication sessions (QSO's as they are called). For contesting, it is important that your log reflects the same time as the party you QSO'd with.
Many old timer's may rely on WWVB and WWVH's running in the HF spectrum from 2.5mhz to 20mhz. These services are fine if you have time to wait for the chimes and are only setting a standard clock or watch. Likewise for the old time communications, the accuracy was allowable.
Communications have changed. The ever present computer now assists in many different aspects of communication, especially logging! Computers however have the least accurate clocks. Computers that are left on for extended periods usually have the worst accuracy of all. Either way, almost all computer's need some form of synchronization more often than most watches or clocks to maintain the same kind of accuracy.
Many forms of electronic and digital time synchronization techniques are available now. There is WWV operating on 60khz but usually requires a fair receiver/decoder to make use of it. The National Institute of Standards and Technology (NIST) maintains dial-in accessible clocks for computer use as does many other branches of the US national government and other governments.
Recently the internet has changed almost all aspects of communication. As with all other communications though, time synchronization is still ever important with the internet. With all that the internet has brought us, it also includes access to the largest interconnected time synchronization network one could ever imagine. Why not keep all clocks attached to the internet in synch with each other?
If you are reading this you likely have a computer attached to the internet in some way. If its not yours, theres some chance that it is already synchronized with a time server somewhere on the internet. If it is yours, is it being synchronized? Synchronization for Unix based or Windows based PC's is not as difficult as one would think. Many different time client software exist, most freely available on the internet.
The internet's most widely used time synchronization system has recently become Simple Network Time Protocol (SNTP). Its an easy entry level time synchronization system with enough accuracy and resolution for general purpose use. SNTP Time Clients, as the software are called, talk to either a SNTP server or a more complicated Network Time Protocol (NTP) server. Either way, they quickly get the time from the server, correct it for network delays, and either report the error or reset the clock to the corrected time. The best clients offer the most options and run in the background keeping the clock synchronized at regular intervals, requiring no more intervention.
Windows XP includes a somewhat limited time client and time server, even in the Home Edition. However, features are quite limited and it operates in quite a quirky manner. I'd recommend disabling it and installing a more complete time client or time server. To fully disable it you must go to the Services manager and disable the W32TIME or Windows Time service.
Below is some references to some clients:
Automachron by One Guy Coding is probably by far the best SNTP time synchronization client for the money (free). The program operates in many of the popular modes from unattended operating to reporting. Its small and compact. It offers taskbar icon, automatic startup, run once, limits and even broadcast support. It does not support "on demand" dial-up access, but does support dial-up connections by quietly waiting for a dial-up connection to be made by other applications. It also supports LAN environments very well.
AboutTime from Paul Lutus (available from the Arachnoid website) is a reasonable SNTP time client. Paul Lutus happens to be an amateur radio operator (KE7ZZ) and writes a lot of different applications and publications. AboutTime is capable of taskbar icons, automatic dial-up, multiple servers, and run once behavoir. The one bonus of AboutTime, it can also be a server!
I'll add more information later, but its from a company called Mount Hay Technology in Australia (www.haytech.com.au). It is shareware however. The server is capable of broadcasting NTP (BNTP) messages. It also does a very good job of filling all the NTP fields.
Now you have a time synchronization client. You probably need a server name for it to use. There are tens of thousands of servers around the world. There are two problems. One, they are not all open for use by just anyone. Two, some are not ideal for use from just any location.
In the NTP and SNTP server arena, there are levels, called stratums. Each stratum reflects a reduction in accuracy. The bottom stratums are the most reliable and accurate and are usually ran by very official body's, such as the NIST. These levels are therefore reserved for others who are in need of a very accurate and reliable server and are therefore usually closed to the general public. It is recommended that the general public use the open bottom level servers very infrequently.
The servers most people should use are stratum 3 or higher. Stratum 3 and 4 servers are often run by local service providers and institutions. Therefore, levels 3 and 4 are usually closer and more numerous. However, just because a server seems local physically, it may be very far away net wise. For the record, here is a link to a list of stratum 2 servers that only require notification to use. They can get a person started in the world of more accurate time.
For closer stratum 3 or 4 servers, check with your internet service provider (ISP). Often it can be found with a little experimentation. Try things like ntp.ISP.COM (or NET) or ntp1.ISP.COM (or NET) or time.ISP.COM (or NET). If you are in my local area, you can try using my server at 12.108.210.94 only if you are a Heartland Inet customer. Requests to 12.108.210.94 will only work reliably for other 12.108.21x.xxx addresses. A server that Midlands Net (Westel Systems) customers can try is ntp1.netins.net. That server is actually a part of the Iowa Network Services group located near Des Moines, IA.
If only a few people served the time and everyone else was to use those servers, the servers would be severely overwhelmed by the traffic. People and institutions with sub-networks (such as home and business LANs) should then desire to serve their own time. By doing so they insure that their own sub-networks have uninterrupted access to time synchronization services.
There are many things to think about with providing a time server. The more clients the server feeds, the more reliable and accurate the server should be. Therefore running a server, one must consider the number of clients he will serve, the source for his own time synchronization, and the hardware that will count the time between synchronizations, in addition to the over all importance of reliable and accurate time.
With all that in mind, an ISP has a very wide line of things to consider. A home user with a small network on the other hand only needs all his machines synchronized together. Unfortunately, the choices in time synchronization software are very limited. For Unix type systems, there are a few packages one can compile and install. Installation is not necessarily easy either. For Windows users, there are far too few decent choices. I am personally using a registered version of Mount Hay Technology's Time Server client/server. I set it to broadcast to the LAN every 150 seconds and to update from my service provider every 17 minutes..
[To Be Completed]