Versatile and accurate method of group-delay measurement

Instruments at present available for measuring group delay are either highly complex (and hence expensive) or offer a limited range of operation and reduced accuracy. This limitation is due to the use of a fixed modulating frequency, which, it is argued here, is an unnecessary restriction. A simple (and hence inexpensive) arrangement is proposed and described, which is capable of measuring group delay over a wide frequency range (100Hz¿2MHz) with high accuracy (up to 1 ¿s) using a modulating frequency which is adjustable from 10 Hz to 1 kHz.