
84 ◾ Lionel R. Watkins
3.3.1 Heisenberg Principle
e foregoing discussion about the rms bandwidth of a function leads
naturally to an important principle in signal processing oen called the
Heisenberg uncertainty because it bears a resemblance to its quantum
mechanical equivalent. In essence, this principle states that we cannot
simultaneously have arbitrarily accurate information about the time and
frequency content of a signal. is follows naturally from the proper-
ties of the Fourier transform and from the fact that time and frequency
are conjugate variables. Suppose, for example, that we have some func-
tion f(t) that is reasonab