See coherent differential phase-shift keying.

Synonym non-return-to-zero mark.

A network, or circuit, that produces an output waveform that is the time derivative of the input waveform.
Note: Differentiating networks are used in signal processing, such as for producing short timing pulses from square waves.

The deviation of an electromagnetic wavefront from the path predicted by geometric optics when the wavefront interacts with, i.e., is restricted by, a physical object such as an opening (aperture) or an edge.
Note: Diffraction is usually most noticeable for openings of the order of a wavelength. However, diffraction may still be important for apertures many orders of magnitude larger… (Read More →)

An array of fine, parallel, equally spaced grooves ("rulings") on a reflecting or transparent substrate, which grooves result in diffractive and mutual interference effects that concentrate reflected or transmitted electromagnetic energy in discrete directions, called "orders," or "spectral orders."
Note 1: The groove dimensions and spacings are on the order of the wavelength in question. In the optical regime, in… (Read More →)

1. In optics, pertaining to a light beam in which the far-field beam divergence is equal to that predicted by diffraction theory.
2. In focusing optics, pertaining to a light beam in which the impulse response or resolution limit is equal to that predicted by diffraction theory. [After 2196]

In radio propagation, a region that is in the geometric shadow of an electromagnetic source, but into which propagation nonetheless takes place by virtue of the knife-edge effect described in Hygens' principle. [JSB]

Differentiated Services

Reflection from a rough or irregular surface which does not maintain the integrity of the incident wavefront.

Knowledgeable individuals at the forefront of Internet development and implementation. [Bahorsky]
Note: Derived from the word "literati. "