Extra exam question E4D10

WhyA third-order intercept level of 40 dBm means a pair of 40 dBm input signals would theoretically generate a third-order intermodulation product with the same output amplitude as either input signal. A third-order intercept point of 40 dBm is a theoretical reference figure: it's the input level at which a pair of equal-strength input signals would, in theory, generate a third-order intermodulation product with the same output amplitude as either of the original signals themselves, a useful way to compare receivers even though real receivers never actually operate at that extreme input level, answer C. It doesn't describe an absolute threshold below which no distortion products form, isn't a headroom-above-noise-floor figure, and doesn't describe a fixed 40 dB gap above a 1 mW reference signal.