A test set for measurement of envelope delay distortion at audio frequencies with 1-microsecond precision

The accelerating use of transmission facilities for data transmission requires an increased knowledge and control of phase characteristics of the facilities and associated networks. These are commonly controlled by specification of a related quantity designated as envelope delay. Specifications have been encountered calling for control or equalization of a switching link to limits of ± 10-¿sec (microsecond) envelope delay over a frequency range of 1,000 to 2,600 cps (cycles per second). Such requirements call for measuring equipment capable of accurately and rapidly measuring envelope delay.