Editing Group delay and phase delay (section)

==True time delay==
A transmitting apparatus is said to have ''true time delay'' (TTD) if the time delay is independent of the [[frequency]] of the electrical signal.<ref name="TrueTimeDelay"/><ref name="Smith"/> TTD allows for a wide instantaneous signal [[Bandwidth (signal processing)|bandwidth]] with virtually no signal distortion such as pulse broadening during pulsed operation.

TTD is an important characteristic of lossless and low-loss, dispersion free, [[transmission lines]]. {{Slink|Telegrapher's equations|Lossless transmission}} reveals that signals propagate through them at a speed of <math>1 / \sqrt{LC}</math> for a distributed inductance {{Mvar|L}} and capacitance {{Mvar|C}}. Hence, any signal's propagation delay through the line simply equals the length of the line divided by this speed.