Third order intermodulation vs signal levelConventional
receivers suffer from third order intermodulation (IM3) at high
signal levels. Inside any device that is not perfectly linear
currents of the second harmonics of strong signals will
circulate. These second order products will mix with other
signals to produce third order interference at frequencies
2F1-F2 2F2-F1 When testing receivers one makes the amplitude of
F1 and F2 equal and then the third order intermodulation product
typically follows the amplitude to power three. This means that
IM3 is reduced by 30 dB when the test signals are reduced by 10
dB and that the IM3 products disappear completely when the test
signals are reduced one third of the way between total breakdown
and the noise floor. Analog receivers have an intermodulation-
free dynamic range. For more details, look here: Intermodulation
in analog receivers Digital receivers behave differently. There
are two distinctly different mechanisms that generate
interference at the same frequency wh