!! Interesting Mathematics

'''Decibels (dBm) and milli-Watts (mW) Relationship:'''
	dBm = 10 log (mW)

'''Typical loss per connector at 2.4Ghz:'''
	0.25 - 0.5 dBm

'''Antenna Gain:'''
	Gain(dBi) = 10 log (n * ( (4*PI)/lambda^2 ) * A)
	Where,	A = Area of antenna
		n = ?

'''Approximate Antenna Gain (Yagi and Omni antennas):'''
	Gain(dBi) = 10 log (#elements)


'''Wave Length:'''
	lambda(mm) = 300 / freq(Ghz)
	(eg for 2.4Ghz, lambda = 123mm)

'''Wave Length (in Coax):'''
	lambda(mm) = 300 / velocity(%) / freq(Ghz)
	(eg LMR400 has velocity factor of 0.85, lambda = 123 * 0.85 = 104.5mm)
	Note: For brass tubing (4/16") use a velocity factor of 0.95

'''Path Loss, Attenuation Due to Air (signal loss in air):'''
	Loss (dB) = 10 log ( ( (4*PI*d) / lambda ) ^ 2 )
	Where,	d = distance (in meters)
		lambda = wave length (in meters)
or for 2.4Ghz use
	Loss (dB) = 40 + 20 log (d)
	Note: Fade margin, usually an additional loss of 10dB is added to take into account things like frensal zones, multipath and other real world stuff


'''EIRP (Effective Isotropic Radiated Power) Calculating:'''
(Transmitter Gain:)
	EIRP(dB) = Card Output(dBm) + Antenna Gain(dBi)
		- Cable Loss(dBm) - Connector Losses(dBm)
	Note: EIRP for 2.4 to 2.462Ghz ISM band must be <= 4W

'''Receiver Gain:'''
	Gr = Antenna Gain(dBi) - Connector Losses(dBm) - Cable Loss(dBm)

'''Link Budget:'''
	Link Budget = Path Loss + Rx Sensitivity + Gt + Gr
	Adjusted Link Budget = Link Budget - 10dB (ie fade margin)
	Note: Use -ve of Rx Sensitivity (ie value is positive, --84 => 84)

'''Over-the-Air Data Rate:'''
	RF Data Rate = (Dpl + Dao + Dro) * (1 + rt) / time
	Where,  Dpl = payload data in bits
		Dao = application overhead in bits/payload transmission
		Dro = radio data overhead in bits
		rt = retry percentage

'''Receive Sensitivity (just read data sheet):'''
	Rx Sensitivity = Thermal Noise Floor + System Noise + 10 log (SymbolRate) + SNR


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See also: PowerAndGainToDecibels