# Dictionary:Analytic signal

(an ∂l’ ∂d ik)

**1**. For a signal such as *f*(*t*), see *Hilbert transform*.

**2**. The analytic signal **A** of a potential field **F** is

where **i, j, k** are unit vectors in the *x, y, z* directions. The **analytic signal amplitude** (also called the **envelope**) is

If |*A*| is derived from a magnetic field, it peaks over contacts and its half-width at half maximum (measured perpendicular to strike) equals the depth of the contact. See also *analytic signal method*.

**3**. For the definition of *analytic,* in this sense, see *Analytic function*.