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Here are some more information for Ghz Parts:

Self-help Book for Wlan Installers/providers

WLAN (Wireless Local Area Network) means technology which allows to build wireless data networks with satisfactory parameters and quite large ranges of operation at a comparatively low cost. Additional advantage of this technology is short time needed for its implementation.

Potentiality of WLANs

* wireless access to local network in home, office, business etc.

* wireless access to the Net in public space, e.g. in airports, stations, cafes etc. (hot-spot)

* wireless point-to-point links (connecting LAN networks, telemetry, remote control, remote monitoring)

* wireless access to the Internet (both in cities and in the country)

* emergency communications link (duplication of wired network)

WLAN standards

I will describe some solutions compliant to the next three standards:

* 802.11a - in 5 GHz band: 5.150 - 5.350 GHz and 5.470 - 5.725 GHz, transfer rate up to 54 Mbps;

* 802.11b - in 2.4 GHz band: 2.4 - 2.483 GHz, transfer rate up to 11 Mbps;

* 802.11g - in 2.4 GHz band: 2.4 - 2.483 GHz, transfer rate up to 54 Mbps;

However, there are also used other standards:

* 802.11f - IAPP - Inter Access Point Protocol - for cooperation between access points;

* 802.11i - standard defining new security methods in wireless networks;

* 802.11n - standard for transmitting multimedia in homes using MIMO technology, up to 300 Mbps;

* 802.11e - standard defining QoS - support for high quality of services;

* 802.16 - WiMax standard for backbone networks of high capacity

Wireless network range

It should be realized that the range of a wireless network depends on many factors; we can have an influence on some of them and the rest is unknown. The range of wireless network depends on:

1. Factors related to used devices:

* output power (it has been decided by the manufacturer),

* cable attenuation (depends on the cable and its length),

* gain of antennas (given by the manufacturer),

* sensitivity of devices (given by the manufacturer).

2. External factors:

* attenuation between antennas (can be estimated basing on FSL model);

* interferences from other devices (can't be predicted - some additional margin of safety needs to be provided to compensate these interferences),

* influence of physical barriers (walls, floors, trees etc.)

So, if we want to know what would be the effective range of our network we have to gather the information mentioned above and carry out simple calculations showed in the further part of this self-help book.

Propagation of radio waves

Fresnel zone

Fresnel zone is one of the most important conceptions connected with propagation of electromagnetic waves, which is indispensable to assess parameters of wireless link. It is the area actively participating in transmission of radio signal energy. Shape of this area is an ellipse in longitudinal section, and circle in cross-section. Radius of this circle is a function of the ratio of distances between antennas - it has the maximum value in the middle of the link. The importance of first Fresnel zone comes from the fact that almost all energy of the signal is conveyed via this space.

The shape of Fresnel zone. R1 is the radius of the I zone.

[m]; where:

* dkm = d1km+d2km, is the distance between masts in km

* d1km - distance from the first antenna in km

* d2km - distance from the second antenna in km

Wrongly made installation. The installer didn't secure mutual visibility of antennas. The radio link does not work.

Another example of wrongly made installation. Presence of barriers in the first Fresnel zone causes that radio link still doesn't work properly.

... it is only the begining... full version of this text you can find on DIPOL library web site (free of charge, no login needed).

About the Author

Text by IT and network specialist. All rights are reserved.

i bought new computer parts but dont know what to do with memory?

Hello people, i have just purchased a motherboard (gigabye G31M-ES2L) a processor (intel pentium inside 2.5 GHz dual core) and 2 ram sticks (each 2 gb). i want to replace my old computer parts with these new ones that i have bought. but the thing is, is that i dont know if my memory from my old compiuter will get deleted. Do i have to somehow save everything before replacing my old motherboard, processor, and ram?
thanks people

I'm not sure what you mean by, "if my memory... will get deleted." If you mean RAM, it always gets deleted b/c it's volatile.

You may mean your hard drive with all your info. If you plan on using the same hard drive on a *different* motherboard, you need to deinstall the old motherboard drivers and install the new ones and reactivate your copy of Windows (If you are running Windows).

This guide was helpful to me and it will be for you: http://www.extremetech.com/article2/0,2845,2343687,00.asp

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