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[I470]Introduction To Computer Systems

by David Evans, Dav

The GPS system is global navigation system introduced by the US military. The system provide navigation and positioning information anywhere on the face of the Earth. The GPS system also provides a highly accurate and precise time and frequency signal ideal for computer timing applications. The GPS system is a orbiting constellation of 24 satellites, each broadcasting time and position information around the globe.

This article describes how the GPS system can be used to provide an accurate time and frequency reference for NTP servers and computer network time synchronisation.

GPS timing information is continuously broadcast by each GPS satellite. GPS time is not affected by leap seconds. GPS time is currently exacly fourteen seconds ahead of Universal Coordinated Time (UTC). However, offset information is available to readily convert GPS time to UTC time, which is used in NTP server and computer time server systems.

Each GPS satellite transmits information as very low-power radio frequency transmission. Two frequencies are used, one for civilian use coded L1, and one for military use coded L2. The civilian L1 frequency is the most widely used and is transmitted at 1575 MHz. The broadcast GPS signal can easily penetrate less dense material such as plastic, but cannot penetrate higher density materials such as brick.

An antenna is utilised to boost the GPS signal and pass the signal along a coax cable. Ideally, a GPS antenna needs to have as good a view of the sky as possible to receive from as many satellites as possible. Ideally, it should be located outdoors on a rooftop with a good 360-degree un-obscured view of the sky.

GPS antennas are very sensitive to cable types and distances. The coax type and antenna gain determines the cable length that can be utilised by a GPS antenna. Higher quality coax cable generally have much lower attenuation figures and hence provide much longer cable runs between the receiver and antenna. Typically, a low-quality coax can run to 20-30m, while a high quality coax can be used in excess of 100m cable runs. To increase these distances still further, a GPS amplifier can be used to amplify and boost the received GPS signal.

GPS timing systems also utilise a GPS receiver in order to decode the received GPS transmission and convert it to a computer readable format. The GPS receiver processes the transmitted GPS positioning information and provides a readable serial transmission as output. GPS NTP servers and computer time servers may also utilise a precise pulse per second output generated by the GPS receiver to provide ultra-precise timing. The pulse per second timing pulse on most receivers is accurate to within a few milliseconds of UTC.

To summarise, the GPS system is ideal for synchronising NTP server and computer time servers. Accuracies of a few hundred nanoseconds can be reasonably achieved with low-cost GPS receiving equipment.

Spyware programs are destructive software that can easily proliferate on the Internet. These spyware are usually attached to downloads, email attachments, and those popups that keep appearing while you are surfing the web. They seem to be harmless, but once they infiltrate your system, the damage that they can potentially cause is monstrous.

Just imagine an intruder entering your home when you're gone. There is no money or jewelry in the house because you keep them in a safe in the bank. But the intruder goes around the house and gathers all the keys you have, and takes note of all your access codes, bank accounts, and other pertinent information that you keep in a tiny notebook in your office desk. While the crook did not steal your appliances, what he got was something better...all the information he needs to render you bankrupt.

This scenario is similar to what happens when spyware enters your system. The malware heads straight to your system registry. There, some changes in registry take place. The spyware registry changes, although seemingly trivial, are all that's needed for the spyware program to cripple your system.

Once the changes are completed by the spyware in the registry, all the information stored in your computer are susceptible to being stolen or transferred to a remote terminal, where unscrupulous individuals may use them for illicit purposes.

Usually, the people who are responsible for the registry changes in your system do have criminal intentions, which is why they propagate the spyware in the first place. But there are also less harmless kinds of spyware. These malware also cause some changes that can cause your system to constantly bog down.

Once the malicious software has made the malicious changes to your system, it guarantees that whenever the computer system is activated, the spyware is activated with it. Therefore all your data are in danger of being stolen anytime, and this can cause very serious trouble.

The spyware registry changes will stay in your system until you delete the spyware program from your system. An anti-spyware software will be able to do this easily for you. There are several of these anti-spyware programs available when you search the web. The software will then remove all registry changes done by the spyware, and restore your registry to its original settings.

Spywares can be avoided in the future by keeping your anti-spyware program updated at all times. Upgrades may be available from the manufacturer from time to time, so make sure you get all these upgrades. For more ino see http://www.pcdatarecoveryhelp.com/Data_Recovery_After_Formatting on recovery after formatting.

It is also important to be more discriminating in clicking links. A lot of spyware come from programs that you inadvertently download from the internet, in the form of email attachments or pop ups.

Be extra careful, and you can almost be certain that spyware registry changes will not happen to your system again. Free data recovery tools are just as good as anything that you would pay for except in one area.

Article Source : Microsoft Outlook Personal Folders

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Both David Evans & David Faulkner are contributors for EditorialToday. The above articles have been edited for relevancy and timeliness. All write-ups, reviews, tips and guides published by EditorialToday.com and its partners or affiliates are for informational purposes only. They should not be used for any legal or any other type of advice. We do not endorse any author, contributor, writer or article posted by our team.

David Evans has sinced written about articles on various topics from Computers and The Internet, Personal Desktop and Computers and The Internet. The author, Dave Evans, is an experienced technical author in the field of computer timing and NTP servers. Dave has written an number of articles in this field. Click here, if you would like additional information on GPS. David Evans's top article generates over 18100 views. to your Favourites.

David Faulkner has sinced written about articles on various topics from Recruitment, Diamonds and Dental Implants. . David Faulkner's top article generates over 201000 views. to your Favourites.