Curious about Wi-Fi

• curious about the Wi-Fi

Many of us have become accustomed to the wireless network as if it is always enveloped the world and allows you to log into the Internet, with only a small communication device (tablet, netbook, smart phone). However, Wi-Fi appeared not so long ago, and although it greatly simplifies the life of modern man, there are some facts that many do not know ...

Wi-Fi was first introduced in Hawaii. ALOHAnet was innovative computer network system developed by the University of Hawaii. It provided the first public demonstration of wireless packet data. This happened in 1971. It was only after 20 years of NCR Corporation and AT & T invented WaveLAN technology, considered a true precursor to Wi-Fi. Then, in 1997, the first version of the IEEE 802.11 wireless protocol has been released.

And back in 1991, the company At & t has released the first device market for wireless data transmission at radio frequency 2.4Ghz. Then this standard wore WaveLan name. He could provide data transmission at speeds of 1 to 2 megabits per second.

In 1997, the world saw the first 802.11. This essentially was the same WaveLan from At & t. A proud name of WI-FI has already received the following specifications - 802.11b. This standard allows data transfer with the speed up to 11 megabits per second.

In 1999, the brand consulting firm Interbrand took the promotion of Wi-Fi technology. It has developed a Wi-Fi logo, which is a variation on the Yin and Yang (alluding to the compatibility of all the products that are certified to work with Wi-Fi).

Contrary to popular belief, Wi-Fi is not formed from the phrase Wireless Fidelity ( "wireless money"). This misconception has appeared because of the early advertising slogan "wireless standard quality". In fact, the name of the Wi-Fi does not mean anything.

In addition, according to the standards of Wi-Fi Alliance (a trade association formed in 1999 to protect the brand) to spell the term with two capital beeches and a hyphen - Wi-Fi. Other writing (WiFi, Wifi, wifi) Alliance does not approve.

Wi-Fi uses radio waves. As you remember from school physics course, radio waves - is a form of electromagnetic radiation. It includes gamma rays, visible light, radio waves, and so on. D.

wireless adapter in your computer or tablet translates data into a radio signal and transmits it using an antenna. Then, the radio waves are received wireless router. He turns them into packets and forwards to the Internet via a wired connection. Information from the web arrives in the reverse order. However, this general description of the process. In Wi-Fi there are a few notable differences from other wireless technologies.

For example: Wi-Fi operates at frequencies 2, 4 GHz or 5 GHz Wi-Fi is much higher than the frequency of mobile communication, however technology allows to transfer large amounts of data. However, all forms of wireless communication represent a compromise between energy consumption, range and bandwidth. So for the sake of high data rates have to sacrifice other options: for example, Wi-Fi consumes a lot of energy and has a limited range.

, you can transfer data faster Wi-Fi, than on the wire! At the moment it is considered the fastest 802.11ac standard. It is capable of transmitting at speeds up to 1.3 Gb / s, which is much faster than a normal telephone wires.

Speed ​​of 1.3 Gb / s for wireless networks - is not the limit. Now it has an active development of a new generation standard - 802.11AD. Its capacity should be at least 7 Gb / s. It is achieved by working in the range of 60 GHz. It is a pity that such a high-frequency band has poor penetrating power and range.

What is the maximum operating range Wi-Fi? Most dial-up connection that is able to establish between the two devices operating at 802.11, is 382 km. This record set Ermanno Petrozemoli.

To do this, it took him a little bit drained series Intel hardware and configure the 2 directional antennas at each other in such a way that they got into a zone of direct visibility. Ermanno managed to squeeze 3 Mbit / s, and for the equipment he has spent only 60 dollars!

Wi-Fi can operate even at a distance of 420 km. And it's true! With the help of Wi-Fi Swedish Space Agency was able to transmit data to a space probe, located at an altitude of 400 km. However itself for transmitting equipment differs from the standard - used 6 watt amplifiers. And, of course, on the signal path there was no physical obstacles.

For a conventional router ranges are much smaller and are determined by a number of factors. Signal strength may depend on the antenna reflection and refraction, and transmitter power. Usually considered a range of 30 meters, but in some cases the signal is lost already in the next room. Why so?

The culprit may be a physical obstacle. Radio waves pass through most obstacles, but they can be absorbed by the materials, electrically conductive. Water conducts electricity, so our body can interfere with Wi-Fi. But do not worry, the radio waves do not cause damage at the cellular level.

Another possible reason - it is interference. Because Wi-Fi uses radio waves (and there are a lot of sources, including the space), they can be superimposed on each other and attenuate the signal. Actually microwave ovens operate at a frequency of 2, 4 GHz, potentially interfering signal Wi-Fi (especially if it has a range of 2, 4 GHz).

Do Wi-Fi radiation is harmful? Such questions often were heard after the people learned that microwave ovens operate on the same with the WI-FI frequency - 2.4GHz.

If a little deeper into the subject matter, it is clear that the WI-Fi signal is completely harmless. Its average thickness of 100 milliwatts, while the household microwave oven operates with a power of 800 watts. Wi Fi completely harmless, because its power is simply not enough to hurt you.

Use public Wi-Fi networks are not secure. Such networks are often used by hackers to collect information. Daily intercepted about 1 terabyte of data. A "leaked" an annual 370 million accounts in the public access. All thanks to the carelessness of users to public networks.

With the help of special software can intercept the traffic between you and the server, and then to attack "man in the middle", pretending to be one of the parties. Thus easily emptied the bank account of the victim. Besides it is possible to intercept passwords or cookie-files with your saved session and without any problems to log into your "kontaktik" or "instagramchik". public networks, avoid to protect themselves. And if we really itch, then use a secure connection over SSL, or use a certified VPN.

Wireless network has been seen as a woman! And not just any girl, associated with science and actress who became famous because of the shooting in the nude. It is similar today are nothing new, and in the 30-40 years of such an act caused a surge in the society (of course, most of the condemned young actress Hedy Lamarr).

Moreover, many considered it frivolous and far away, but it was this girl came up with a system that manages the torpedoes from a distance - it is this development became the basis for today's Wi-Fi.