Archive for January, 2010
About GPS
Global Positioning System
The Global Positioning System (GPS) is the only fully functional Global Navigation Satellite System (GNSS). Utilizing a constellation of at least 24 medium Earth orbit satellites that transmit precise microwave signals, the system enables a GPS receiver to determine its location, speed/direction, and time.
Developed by the United States Department of Defense, it is officially named NAVSTAR GPS (Contrary to popular belief, NAVSTAR is not an acronym, but simply a name given by Mr. John Walsh, a key decision maker when it came to the budget for the GPS program[1]). The satellite constellation is managed by the United States Air Force 50th Space Wing. The cost of maintaining the system is approximately US$750 million per year,[2] including the replacement of aging satellites, and research and development. Despite these costs, GPS is free for civilian use as a public good.
GPS has become a widely used aid to navigation worldwide, and a useful tool for map-making, land surveying, commerce, and scientific uses. GPS also provides a precise time reference used in many applications including scientific study of earthquakes, and synchronization of telecommunications networks.
Simplified method of operation
A GPS receiver calculates its position by measuring the distance between itself and three or more GPS satellites. Measuring the time delay between transmission and reception of each GPS microwave signal gives the distance to each satellite, since the signal travels at a known speed – the speed of light. These signals also carry information about the satellites’ location and general system health (known as almanac and ephemeris data). By determining the position of, and distance to, at least three satellites, the receiver can compute its position using trilateration.[3] Receivers typically do not have perfectly accurate clocks and therefore track one or more additional satellites, using their atomic clocks to correct the receiver’s own clock error.
How to Trace Hackers
Ever wondered how hackers function and what you can do to find someone that is hacking into your system. Read through the following article for some answers.
If you want to know how to trace hackers then you will find some answers in the following paragraphs. The first thing that they need, to be able to get into your system is your IP address. One way that can get your IP address is from the header information from emails that you send. Included in header information is the IP address of where the email is being sent from and once they have this they can access you.
Since there are now two kinds of IP addresses, the static and dynamic, hackers are generally able to access people with static IP addresses or using DSL lines. So if you are operating with dynamic IP addresses hackers are of little concern to you.
One way of how to trace hackers is to use a tool referred to as the NETSTAT tool. Using this tool you will be able to see who is connected to you. On your PC go to start, click programs, choose MSDOS prompt and then type in “netstat -a”. There must be a between the last t and the a’. The screen will then display a list of active connections. It will show a local address, that is the address of your PC and the ones that they say foreign address are the ones that are connected to you.
There are various NETSTAT commands that will help you understand the workings of your network better. If you want to know how to trace hackers, I recommend that you learn as many of these commands as you can. Once you know them, then you are set.
Facts to Consider Before Purchasing an Unlocked Cell Phone
One of the most asked questions we receive at Search4cellphonedeals.com is can I use any unlocked cell phone for my carrier? The short answer is, no you cannot. There are several things to consider before you run out and buy an unlocked cell phone.
First let’s look at what an unlocked cell phone is. Some cell phones are designed to use a Subscriber Identification Module card or SIM card for short. A SIM card is a microchip that stores subscriber data. The SIM card is issued by a carrier and provides cell service by activating any phone into which it is inserted. A locked cell phone, however, will only recognize a SIM card from a particular carrier. If the cell phone is unlocked, it will recognize a SIM card from any carrier. The “lock” is a software setting that keeps the cell phone “loyal” to one carrier. This is done by the major carriers to ensure you don’t get a FREE cell phone under a two-year contract and then not pay on the contract and use that cell phone with another provider. It is in this way that the cell phone providers can justify giving individuals a FREE cell phone that would have otherwise cost the consumer money.