  Electromagnetic remote sensing technologies such as radar can be mislead by
targets that generate spoof pulses. Typically, a would-be spoofer must make
measurements to characterize a received pulse in order to design a convincing
spoof pulse. The precision of such measurements are ultimately limited by
quantum noise. Here we introduce a model of electromagnetic spoofing that
includes effects of practical importance that were neglected in prior
theoretical studies. In particular, the model includes thermal background noise
and digital quantization noise, as well as loss in transmission, propagation,
and reception. We derive the optimal probability of detecting a spoofer allowed
by quantum physics. We show that heterodyne reception and thresholding closely
approaches this optimal performance. Finally, we show that a high degree of
certainty in spoof detection can be reached by Bayesian inference from a
sequence of received pulses. Together these results suggest that a practically
realizable receiver could plausibly detect a radar spoofer by observing errors
in the spoof pulses due to quantum noise.
