A D/U ratio is measured for desired and undesired signals in a wireless video transmission system at a shared channel frequency based on a received signal at a geographic location in proximity to regions within respective service areas for the desired and undesired signals. A video tuner demodulates the received signal to generate a baseband video signal. A leveling circuit normalizes the baseband signal. A video processor identifies horizontal sync pulses within the baseband signal, generates a sampled signal comprising the horizontal sync pulses, and removes components of the desired signal from the sampled signal to generate an undesired signal component. A D/U analyzer determines a Fourier transform having a plurality of bins in response to the undesired signal component, identifies at least one of the bins having a spectral peak corresponding to an undesired signal, and calculates the D/U ratio in response to a magnitude of the identified peak.