| 摘要 |
PURPOSE:To obtain a high-precision measurement even for an AGC-system digital transmission system by changing either one, at least, of the amplitude and the timing of a digital signal, which is given to an object to be measured, at the interval of a time sufficiently short for the control time constant of an AGC by the time shorter than the interval to eliminate the influence of the AGC. CONSTITUTION:The value of the amplitude of a signal shown in Fig. (A) is stored in a word pattern generator 21 by 8-bit information, and a code converter 23 converts this signal to a ternary digital signal to generate the signals having various amplitudes. This output is inputted to an object 14 to be measured through a transmission medium 12. The object 14 to be measured has a signal discriminating circuit. By this constitution, the transmission pulse amplitude is reduced or increased by the code converter 23 to observe the limit of the amplitude generating a pulse loss error or insertion error by an error detector 15 with respect to the measurement of the degree of a margin of discrimination in an amplitude axial direction. Since the operation of the transmission pulse amplitude is executed in such low frequency that AGC does not respond, it has no influence upon the operation of a normal AGC amplifying system. |
