ABSTRACT
Least interesting of these shivers are the ones with a perfectly steady frequency, no variation to them at all. The next-to-least interesting are the frequency-modulated kind, now faster now slower depending on information put in at the other end, wherever that might be. Then you have the irregular waveforms that change both in frequency and in amplitude. They have to be Fourier-analyzed into their harmonics, which is a little tougher. There is often coding involved, certain subfrequencies, certain power-levels-you have to be pretty good to get the hang of these.
