OBJECTIVE CRITERIA FOR ESTIMATING THE QUALITY OF ANALOG SIGNAL TRANSMISSION OVER DIGITAL CHANNELS

The use of different methods of digital modulation in digital communic ations networks and the increase in the number of algorithms of the fu nctioning of codecs and speech-conversion devices has made it extremel y difficult to obtain a reliable estimate of the quality of the transm ission of analog signals over digital channels. The universality of to ne-frequency channels necessitates estimating them using a number of p artial criteria, which leads to an increase in the time taken to obtai n information on the suitability of a channel and complicates the meas uring apparatus. With the introduction of digital transmission systems , the dependence of such parameters of tone-frequency channels as the residual attenuation and its frequency characteristic mainly only on t he characteristics of the system used for the digital conversion of th e analog signals provides a basis for estimating channels using genera lized criteria usually employed to investigate the quality of codecs a nd speech-conversion devices. This approach means that the estimates o btained for the quality of analog channels of digital transmission sys tems are similar to criteria employed by subscribers to estimate commu nications quality.