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03/24/2011
Wireless Access Points and Garmin GPS (Global Positioning Satellite) BLOG#2
http://compnetworking.about.com/cs/wireless/g/bldef_ap.htm
Small businesses and home networks can use devices that are specifically pre-configured and dedicated to serve as wireless access points (also known as WAN'S or AP's). These access points have nodes that are configured and designed to act as a central receiver and transmitter of the wireless local area networks (LAN's) radio signals. The access points support communication via the wireless WI-FI standards.
It is true that some very small WLAN's can function via "ad-hoc" or peer-to-peer mode as access points to support the mode of infrastructure. It should be noted that the "ad-hoc' supporting infrastructure mode bridges wireless local area networks (that use no physical wires) with a wired local area network, therefore more clients are able to be served. Many newer access points can now support up to 255 clients whereas the first "base model" access points could only serve up to a 20 client maximum.
http://www8.garmin.com/aboutGPS/
GPS is a Global Positioning Satellite-based navigational system. The system ids free of charge, works worldwide and in any weather conditions.
A network of 24 satellites that have been placed in orbit by the US Department of Defense make up the GPS system. Originally GPS was intended only for military applications but it became available to civilians in the 1980's.
Two times per day the satellites preciselycircle the earth and constantly and consistently transmit information back to the receiver's units on the earth. The satellites travel at speeds of 7000 miles per hour at 12000 miles above our planet. It is the GPS recievers that calculate exact positions. The receivers compare what exact time a location transmision was received with the time the transmission was sent to configure a users exact positional location and display it almost instantly on the users unit electronic map. Once the GPS has calculated a user position it also has the capabilities of computing information such as speed, trip distance, the sun's location, distance to destination and more.
Global Positioning Satellite systems are extremely quick and accurate in determining location within an error for margin of 15 meters. The GPS system can pin-down a location even in tall buildings in suburban setting or in the thick of the woods in seemingly un-navigational locations. There are now newer GPS receivers with Wide Area Augmentation Systems (WAAS) with improved capability to determine accurate coordinates within 3 meters.
Interesting facts about the GPS System
- In 1978, the first GPS satellite was launched.
- In 1994, the first full constellation of 24 satellites was acheived.
- 10 years is the estimated lifespan of each satellite. They are continually being rebuilt and launched.
- The weight of a Global Positioning Satellite is about 2000 pounds and with the solar panels extended, the satellite measures approximately 17 feet across.
- The transmitter power is 50 watts or less.
Sources of error signals include, Ionosphere and troposphere delays- the satellite slows as it passes through the atmosphere. Signal multipath occurs when signals are reflected or deflected off of objects. Sometimes there are slight timing errors in different clocks such as atomic clocks meshing with the GPS satellite clocks. Also, intentional degradation of the GPS signals by the U.S. Department of Defense, called Selective Availability (S.A.) was used to protect the United States from military adversaries. S.A. was once a source of signal error to civilians. The U.S. government turned S.A. off in may 2000, which significantly improved signal accuracy.
03/23/2011
Hard Drives and maintaining the Hard drive Integrity (BLOG#1)
http://computer.howstuffworks.com/hard-disk.htm
http://computer.howstuffworks.com/hard-disk1.htm
http://hubpages.com/hub/maintaining-hd-integrity
Hard Disk Drives and Maintaining their Integrity:
Hard disk drives are present on most servers and desktop computers. Super computers and mainframes can be connected to hundreds of hard drives.
In the 1950's hard diskd were invented. A "Winchester" or "Fixed Disk" were the original terms used to describe what is now known as the Hard Disk.
A hard disk is a magnetic medium that is stored on a 'hard platter' . Alternatively, floppy disks and cassette tapes are magnetic mediums that are held in thin, plastic film cases. Yet both cassette tapes and hard disks are similiar as they both use magnetic recording and share the benefits of magnetic storage. Magnetic meduims can easily be rewritten or erased, yet still remember the "flux" pattern.
It is critical to maintan a hard disk drives integrity. One risks losing all of their information, files, homework, pictures and more by not keeping the HD integrity maintained and backed up. It should also be noted, that magnets should be kept away from your computer as a magnet can erase all of your data and can render disks to become inoperable.
When possible always use a surge protector and and frequently back up your data. In today's market, backing up your information can easily be done by using external hard drives, flash drives and DVD's. Back up all information that you can not replace or afford to lose.
It is also imperative to keep your computer free of adware, malware, spyware and viruses. Those specific problems can corrupt your hard drive, internet connection , change your data, share your data and most importantly cause data loss.
Do not ignore maintainance of your computers hard drive, keep it protected. The risk of disk failure and data loss are huge if the integrity of your computers hard drive is compromised.
