Abstract: A system for measuring the attenuation on a transmission path for a random signal in which the propagation time of said signal is between a lower limit T1 and an upper limit T2, the system comprising:a first maximum value indicator circuit with immediate response and a holding time not less than T2, to which the signal at the input end of said path is applied;a second maximum value indicator circuit with immediate response and a holding time not less than T2-T1, to which the signal at the output end of said path is applied;a detector which detects that the output of said first indicator has been maintained constant during a time interval not less than T2, connected to receive the output signal from said first indicator and determining times at which the indicator output signals are recognized; anda processor connected to receive the indicator output signals, controlled by said detector and generating a measurement signal which is a function of the instantaneous value of the ratio of the indicator output signa