FIELD: instruments, in particular, calibration of measuring channels for detection of their amplitude and phase characteristics. SUBSTANCE: dividend signal x(t) is divided by divisor signal y(t) in order to achieve quotient signal f(t) = x(t) / y(t) for time t1 which corresponds to middle point of half- wave of divisor signal y(t). Quotient signal f(t1) and its derivative f'(t1) are measured and amplitude ratio K is calculated using equation 
. EFFECT: increased speed, simplified design. 2 dwg
