GB1115064A - Procedure for measuring group delay-time - Google Patents

Abstract

1, 115, 064. Group delay measurement. TAVKOZLESI KUTATO INTEZET. May 20, 1965 [May 20, 1964], No.21470/65. Heading G1U. In an arrangement for measuring group delay time, a varied frequency is transmitted through the network under test and at the receiver is passed into two channels in one of which it is delayed. The outputs from the two channels are compared in phase, and since the delay has the effect of giving one output a frequency shift relative to the other at any given instant (since the frequency of the input to the system is continuously changing) this phase difference represents the group delay at each instant. Signals from a fixed frequency generator 1 and a wobbulator 2 are mixed at 3 and passed to the network X under test. The output from X is converted to an I. F. frequency at 5 by mixing with a signal from a generator 6 varied in accordance with the wobbulater 2. The I. F. signal is passed to a buffer circuit 7 which passes it directly to a phase difference measuring circuit 8 and also to a delay 9 whose output provides the other input to the circuit 8. The output from the phase difference circuit 8 passes via a channel switch 9 to be displayed on an oscillograph 14 which is calibrated by frequency markers derived through a channel 4. Calibration of the system is achieved through a separate phase adjusting, measuring and delay system 10, 11, 12.