NON-INTERFERING METHOD FOR MEASURING PROPAGATION DELAY OVER TELECOMMUNICATIONS NETWORK AND APPARATUS FOR ACCOMPLISHING SAME

摘要

ABSTRACT OF THE DISCLOSUREMethods and apparatus for measuring propagation delayover a line without interfering with data communications overthe line are disclosed. A known signal is sent and loopedback over a secondary channel, and the loop time is measured.Because the known signal is sent at a non-interferingfrequency at the edge of the passband, the loop time minusfixed delay times of the communicating means does not providea true measure of propagation delay. Rather, the envelopedelay distortion must be determined and also subtracted fromthe loop time. The envelope delay distortion is determinedas a function of the utilized non-interfering frequency andthe line length, the latter of which may be estimated fromthe loop time.