A Measuring Complex for Automatic Evaluation of Nonlinear Distortions
E. M. Rudy · Telecommunications and Radio Engineering · 1997
In 1950 V.M. Wolf suggested (author certificate No. 90158TJSSR) a method for measuring nonlinear distortions in which frequency components in a narrow band are removed from the spectrum of the useful signal. At the receiving end the nonlinearity is estimated by the level of harmonics and combination frequencies detectable in the band containing no intelligence signal. The spectra of human speech and musical instruments are characterized by a pronounced line structure, i.e. the major portion of energy is concentrated within a narrow frequency band [1]. The line spectrum signals can be used for nonlinear distortion evaluation by comparing them at the input and output of a communication channel [2]. The possibility has been implemented in a device that automatically selects of all the incoming signals those with a highly suppressed (or absent) predetermined frequency band. Nonlinear distortions are estimated in terms of magnitudes of nonlinear products in a predetermined frequency band at the output of the communication channel (author certificate No. 1084997TJSSR). Different signals have different parts of their frequency spectra suppressed, thus nonlinear distortions can be estimated in different areas of the frequency band without distorting the signals transmitted through the communication channel.