"I believe thatThe distinction between entity that doesn't exist, and a function that does, applies equally well to spectrum. (I outlined my argument regarding spectrum in Newton, Leibnitz and the (non?)existence of spectrum; for more detail, see my article De-situating spectrum: Rethinking radio policy using non-spatial metaphors.) To mash-up William James:consciousness,when once it has evaporated to this estate of pure diaphaneity, is on the point of disappearing altogether. It is the name of a nonentity, and has no right to a place among first principles. ... For twenty years past I have mistrustedconscousnessas an entity: for seven or eight years past I have suggested its non-existence to my students, and tried to give them its pragmatic equivalent in realities of experience. It seems to me that the hour is ripe for it to be openly and universally discarded.
"To deny plumply thatconsciousnessexists seems so absurd on the face of it — for undeniablythoughtsdo exist — that I fear some readers will follow me no farther. Let me then immediately explain that I mean only to deny that the word stands for an entity, but to insist most emphatically that it does stand for a function." (My italics.)
To deny plumply that "spectrum" exists seems so absurd on the face of it — for undeniably "signals" do exist — that I fear some readers will follow me no farther. Let me then immediately explain that I mean only to deny that the word stands for an entity, but to insist most emphatically that it does stand for a function.In other words, the proper subject of both psychology and wireless regulation is behavior and its results. This becomes all the more important as radios become more sophisticated.
A simple example: in the white space proceeding, the FCC specified different maximum transmit powers for different kinds of unlicensed radios, but required that they all avoid wireless microphones using the same detection sensitivity. This doesn't make engineering sense, since the radius of interference for weak radios is smaller, and they therefore do not need to detect microphones at the same range as strong radios. Their detection therefore doesn't have to be as sensitive. A more efficient alternative would be for the unlicensed radios to vary their detection sensitivity depending on their transmit power. The "usable spectrum" is therefore a function of the behavior of the radios concerned, and not just frequencies.
In a similar vein, the boundary between "spectrum licenses" is not really -- or not just -- a frequency, as it might at first sight appear. (Let's leave aside geographical boundaries.) There is no sharp edge, with a radio allowed to transmit any power it wishes "inside its spectrum", and none at all "outside". Instead, there's a gradation of decreasing power for increasing frequency difference. There isn't a boundary where one thing ends and another begins; rather, the boundary is a behavior. This underlines that spectrum, like consciousness for Henry James, isn't an entity, but rather a function.