what is
GPS
by admin on Jun.17, 2009, under device, mobile, mp3players, what is
The Global Positioning System (GPS) is a global navigation satellite system (GNSS) developed by the United States Department of Defense and managed by the United States Air Force 50th Space Wing , It made up of a network of 24 satellites It is the only fully functional GNSS in the world, can be used freely by anyone, anywhere, and is often used by civilians for navigation purposes.

GPS satellites circle the earth twice a day in a very precise orbit and transmit signal information to earth. GPS receivers take this information and use triangulation to calculate the user’s exact location. Essentially, the GPS receiver compares the time a signal was transmitted by a satellite with the time it was received. The time difference tells the GPS receiver how far away the satellite is. Now, with distance measurements from a few more satellites, the receiver can determine the user’s position and display it on the unit’s electronic map.

A GPS receiver must be locked on to the signal of at least three satellites to calculate a 2D position (latitude and longitude) and track movement. With four or more satellites in view, the receiver can determine the user’s 3D position (latitude, longitude and altitude). Once the user’s position has been determined, the GPS unit can calculate other information, such as speed, bearing, track, trip distance, distance to destination, sunrise and sunset time and more.
Putting GPS to work
GPS technology has matured into a resource that goes far beyond its original design goals. These days scientists, sportsmen, farmers, soldiers, pilots, surveyors, hikers, delivery drivers, sailors, dispatchers, lumberjacks, fire-fighters, and people from many other walks of life are using GPS in ways that make their work more productive, safer, and sometimes even easier.
Examples of real-world applications of GPS fall into five broad categories :
- Location – determining a basic position
- Navigation – getting from one location to another
- Tracking – monitoring the movement of people and things
- Mapping – creating maps of the world
- Timing - bringing precise timing to the world
IP Number
by admin on Jun.15, 2009, under what is
IP is an address of a computer or other network device on a network using IP ” TCP/IP ” , ex : “140.23.10.23″ . These addresses are similar to addresses used on houses and help data reach its appropriate destination on a network.
To make it easier for us humans to remember, IP addresses are normally expressed in decimal format as a “dotted decimal number” like the one above. But computers communicate in binary form. Look at the same IP address in binary:
11011000.00011011.00111101.10001001
The 32-bit IP address is grouped eight bits at a time, separated by dots, and represented in decimal format (known as dotted decimal notation). Each bit in the octet has a binary weight (128, 64, 32, 16, 8, 4, 2, 1). The minimum value for an octet is 0, and the maximum value for an octet is 255.

The Internet Assigned Numbers Authority (IANA) manages the IP address space allocations globally. IANA works in cooperation with five Regional Internet Registries (RIRs) to allocate IP address blocks to Local Internet Registries (Internet service providers) and other entities.
When you send or receive data (for example, an e-mail note or a Web page), the message gets divided into little chunks called packets. Each of these packets contains both the sender’s Internet address and the receiver’s address. Any packet is sent first to a gateway computer that understands a small part of the Internet. The gateway computer reads the destination address and forwards the packet to an adjacent gateway that in turn reads the destination address and so forth across the Internet until one gateway recognizes the packet as belonging to a computer within its immediate neighborhood or domain. That gateway then forwards the packet directly to the computer whose address is specified.
Because a message is divided into a number of packets, each packet can, if necessary, be sent by a different route across the Internet. Packets can arrive in a different order than the order they were sent in. The Internet Protocol just delivers them. It’s up to another protocol, the Transmission Control Protocol (TCP) to put them back in the right order.
Ferrite bead
by admin on Feb.24, 2009, under Computer, hardware, what is
‘Ferrites’ are a class of chemical compounds with the formula AB2O4, where A and B represent various metal cations, usually including iron. These ceramic materials are used in applications ranging from magnetic components in microelectronics.

You normally see these “bumps” on the mouse, keyboard and monitor cables. You can also find them on power supply wires when a device (like a printer or scanner) uses an external transformer.
These “bumps” are called ferrite beads or sometimes ferrite chokes put to reduce EMI (electromagnetic interference) and RFI (radio-frequency interference).
It is a passive electric component used to suppress high frequency noise in electronic circuits. Ferrite beads employ the mechanism of high dissipation of high frequency currents in a ferrite to build high frequency noise suppression devices. Ferrite beads may also be called ferrite cores, ferrite rings, ferrite EMI filters.
These cables act as nice, long antennae for the signals they carry. They broadcast the signals quite efficiently. The signals they broadcast can interfere with radios and TVs. The cables can also receive signals and transmit them into the case, where they cause problems.
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