Basic RF Fundamentals

RF Basics:

•Frequencies(Specific location in RF space):How often an RF wave cycles per sec
•Waves(Actual medium we manipulate to send Data) components includes: Wavelength, Amplitude, Phase(in/out).
•Radios(The radio do the job of transmitting and receiving data).
–Wavelength=360* movment of an RF wave
–Amplitude=powerleve of an RF frame
–Phase=The relationship between two signal based on when their alternate current       raising and falling.
–Frequency=Number of wavelength in Sec.

•Five RF Fundamental



2.4–>Lower Frequency (2.4 billion cycle/sec)

 Channel:5 Ghz

                            –5Ghz for wlan is divided into UNII band 1,2,3
                            –ISM band is now added in UNII band 3
                            –Channel 169 is a 20mhz only channel.
                            –Channel 144 is just got added, no not much devices are using that.

 RF Behaviour:

                                –Behavior of RF defers based on the surface it impacts with.
                                –Reflection ,Absorption,Scattering,Refraction,Diffraction.
                                –Reflection and Absorption converts the RF into heat.
                                –These RF behavioral changes are taken advantage in N and AC                   networks                                 because of MIMO technologies.

   RF Measurements:

                          –Inorder to connect at higher MCS rate the device needs to operate in higher                                QAM
                          –Device to operate at 64 and 254 QAM, it needs to get connected at high SNR

  RF Interference:

                            –When an external modulated or Un-modulated RF influences affect the                                        ability of the RF receiver is called RF interference
                            –Interference happens at the receiver
                            –Low duty cycle interference can be tolerated.
                            –High duty cycle interference can wreak havoc on the channel

  RF Analysis :

                       –We have different type of interference and the non Wifi interference are the                                ones which stays unknown mostly in our network.
                       –We have Tools which should be able to help you in finding out the wifi and                                   non wifi interference in you network.
 Tools for spectrum analysis and Site survey:
                                           AirMagnet Wi-Fi spectrum XT
                                           Ekahau Site Survey pro with planner
                                           metageek wispy DBX with channalyzer pro
                                           Metageek inSSIDer
                                           Xirrus WI-FI Inspector
Snap Shot Courtesy by CWNP

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