You don't need to do anything fancy to lose FM reception. As a result of multipath interference, I can frequently be sitting at a traffic light in my car and be getting perfect reception, but if I creep forward just a few feet, reception will be totally lost. My HDTV's reception (via a small indoor antenna) goes from perfect to terrible, on windy days, due to the fact that the demodulator cannot track the rapid variation in multipath caused by the swaying tree branches behind my house.
A "well engineered" FM demodulator is far from a linear LOS; a phase locked loop is used to, in effect, continuously retune a narrow bandpass filter, with a bandwidth much less than the overall signal bandwidth, to track the narrow "instantaneous bandwidth" of the FM carrier and thereby greatly reduce the effective receiver noise level - but only as long as the signal remains "above threshold".
"which indicates that some variable does exist which reacts across the classical spread wavefront of a modulated transmission" But that variable has nothing to do with any individual photon, anymore than the properties of water waves are innate properties of water molecules.
QM does not say that "photons (particles) exist everywhere all at once"; as Einstein et. al. suggested, only the absurd interpretations of QM say that. But such interpretations are no longer required; it has been demonstrated that classical objects, constructed to manifest only a single-bit of information, will reproduce all the seemingly weird behaviors that have so befuddled the physics world, for nearly a century.
In that context, it is important to realize that "information" as Shannon defined it, has little to do with "entropy" or even physics in general (most unfortunate that von Neumann persuaded him to name it "entropy"); it is a purely mathematical concept concerning the ability to perfectly reconstruct a continuous function from discrete samples. It is most unfortunate that the physics world has confused the two concepts. Shannon's concept, is key to understanding the "measurement problem".
It is easy to demonstrate that QM boils down to little more than the mathematical description of an energy detecting filterbank (a Fourier transform's power spectrum). When you send particles (quanta) with equal energy into the various channels of the detector, the ratio of total energy received in a channel, divided by the energy per quanta in the channel, enables one to infer the number of received quanta in each channel, thereby rendering the entire process as being simply equivalent to a histogram; that is the origin of the Born rule. No mysterious wavefunctions, wafting through the cosmos, are required to understand what is actually going on.