| 摘要 |
A method and device for measuring the slope of the envelope delay characteristic of a transmission channel and deriving the phase intercept value therefrom. A measurment signal having a frequency spectrum including three rays at frequencies fo, f1 and f2 is sent over the transmission channel. Frequency fo is the carrier frequency and frequencies f1 and f2 are defined as f1=fo-1/2T and f2=fo+1/2T, where 1/T is the signaling rate. At the output of the channel, the three components at frequencies fo, f1 and f2 are extracted from the received measurement signal, and the instantaneous phases psi o, psi 1 and psi 2 of these three components are then measured. The value of the slope S of the envelope delay characteristic is obtained in accordance with the relation <IMAGE> where phi o', phi 1' and phi 2' are the phases of the three rays at frequencies fo, f1 and f2 of the measurement signal sent over the channel. The value of the phase intercept phi i for a given sampling phase phi s is determined in accordance with the relation phi i= phi o-K S where phi i is the phase of the component at frequency fo received at the instant <IMAGE> K is a proportionality constant lying between 0 and 1, and S is the slope expressed in milliseconds.
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