PC's keep time, even when the computer is turned off, using battery-backed real time clock (RTC) chips. The RTC chips are mass-produced low-cost components that generally do not have good time keeping properties and have a tendency to drift. This article discusses a number of ways to maintain accurate time on a PC. It also provides information on how to synchronise a PC's time with precise Internet and national time and frequency radio transmissions.
Computer systems time can drift anything from a few seconds a day to a few minutes each day. When processing transactions or performing time critical tasks across a number of computers, incorrect time can be a real headache.
The Internet found and solved this problem a number of years ago by developing the Network Time Protocol. NTP can be used to distribute accurate time from a highly precise time server to network time clients. Most modern operating systems have the ability to synchronise time with a NTP server. Generally, all that is required is the IP address or domain name of Stratum 1 or Stratum 2 NTP servers.
LINUX and UNIX operating systems can download the full NTP implementation from the NTP web site 'ntp.org'. NTP is freely available open source software available under the GNU public licence.
Microsoft Windows XP/2000/2003 and Vista operating systems have an integrated SNTP client. SNTP stands for Simple Network Time Protocol. Simple Network Time Protocol provides a sub-set of the Network Time Protocols algorithms. SNTP provides a simplified NTP algorithm with many of the complex routines to acheive high precision removed. Windows operating systems allow an IP address or domain name of a Internet or Intranet NTP server to be entered in the time properties tab. The SNTP client will then periodically contact the NTP server in order to update and synchronise system time.
A problem arises, however, if the computer does not have access to the Internet or is not networked. What is required is local access to an accurate time reference. Luckily, a number of precise freely available timing references are available to the public.
A number of national radio time references are transmitted free-to-air. These radio broadcasts are generally referred to by their 'call sign'. WWVB is the North-American time and frequency radio transmission, broadcast for Colorado in the States. DCF is the call-sign of the German radio time transmission, which is broadcast from Meinflingen near Frankfurt. The UK time transmitter is located at Anthorn, Cumbria, it's call sign is MSF. A number of other broadcasts are available in France, Canada, Switzerland and Japan. With the addition of a small RS232 serial or USB radio receiver, a PC can obtain continuous accurate time. The PC system time can then be synchronised to the received time and frequency radio source.
The problem with national radio time broadcasts is that they inherantly have a finite transmission range. Their transmissions are generally regional and limited to national boundaries. The Global Positioning System (GPS) provides a solution to this. The GPS system operates from a number of orbiting satellites. Each satellite has an on-board highly accurate synchronised atomic clock. GPS can provide highly precise timing information anywhere on the face of the planet. All that is required to receive the GPS transmissions is a low-cost GPS receiver and antenna. The GPS antenna needs to be shown a good clear view of the sky for correct operation. By connecting a PC to a serial or USB GPS receiver, accurate timing information is continuously available.
To summarise, a wide range of highly accurate computer timing references are freely available. Utilising the Internet, National time and frequency radio transmissions or the GPS system can ensure that a computers time remains locked to a precise time reference.
There are a lot of things that you will want to ask your potential hotel, but you will definitely want to ask about discounts that you could possible get. There are a various types of discounts and you will want to take some of the following information inconsideration when planning your next overnight trip. First you may want to search the internet and look for some really low rates. You will find that there are a number of sites online that offers travel arrangements at discount and you will want to go to these sites and see what type of discounts you could get. You will also want to plan your trip during the seasons when tourist is low. This means you don't want to plan your trip in middle of summer. You will need to take a possible fall or winter trip, but you could also take an very early spring trip. You definitely don't want to deal traveling with all those other people cramping themselves into the or wherever you are travelling. Plus security is at the worst during the summer. Also you will want to call the hotels that you are looking at and see what they are offering that makes them special or if they are willing to give you a discount. You may find that with the competition you could get a discount based on other hotel rates. You will also want to consider paying on credit card. Even though credit cards are seemed as an "evil", you may be able to get a discount just because you are paying with a credit card and you will also want to mention this when you call and talk to the hotel manager. You will also want to make sure that you try to be reasonable in the negotiations too. You may also want to drop a name if you have that option. Most people will only say someone else's name if they tend to stay a lot at that hotel. You will also want to check out some of the packages that the hotel will offer to you so that you can save yourself some money overall in the trip. If you are in the military or you are a veteran, you may be able to get discounts through the government or they may be offered through the hotel chain. Make sure that you think about asking about such a discount when you are looking to make a reservation. You will also want to make sure that you think about some of the extras in a hotel rate, because that doesn't include extra things like food and you may even find high taxes for hotels when you are traveling abroad.
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David Evans has sinced written about articles on various topics from Computers and The Internet, Personal Desktop and Computers and The Internet. David R. Evans is an experienced technical author whose field of expertise are NTP servers and computer timing systems. Click here for more information about Radio and GPS time servers and. David Evans's top article generates over 18100 views. to your Favourites.
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