circuit 31 of the first volume 101 closes for a certain time period equal to the memory time length of the volume when the gate 101 opens the gate to the next volume 32 closes instantaneously whereafter the next time period of the analogue signal is input to the volume 32 this operation is repeated sequentially for the series of volumes thus an analogue signal of a time length equal to the sum of the time lengths of the individual volumes is stored in this circuit system fig4 is a block diagram of another embodiment of this invention this embodiment allows for comparison of two worm signals a signal stored in one volume is compared with another signal in another volume this enables a judgment as to whether the two signals are identical similar or different a signal to be tested is stored in a volume 105 which is of the type shown in fig1 via gate circuit 35 this stored worm signal is constantly read out from an output terminal 55 a file data signal is stored in a second volume 106 the output of the second volume is derived from an arbitrary position of the delay element by a switch 42 connected to an output terminal 56 the outputs of the two volumes are connected to the two inputs of a differential amplifier 120 if the output of the differential amplifier is zero the two signals are identical if it is a dc value the two have similar wave.