Any introductory tutorial will immediately introduce the decibel (dB) as the lingua franca of link analysis. Decibels are used because signal power can span many orders of magnitude; adding and subtracting logarithms is far easier than multiplying and dividing large numbers. The fundamental link budget equation is:
Noise Power (dBm) = 5 dB + (-174 dBm/Hz) + 10log10(20e6) = -121 dBm Tutorial on Basic Link Budget Analysis.pdf
: Miscellaneous losses (cables, connectors, atmospheric fade) Key Components of the Link Budget 1. Transmit Side: EIRP Tutorial on Basic Link Budget Analysis.pdf