FIELD: magnetic recording and playback equipment. SUBSTANCE: two memory units convert information word from set of code words and store word, which direct current value is positive and negative. Signal which is read from memory unit by means of access unit is converted into respective format by means of converter from parallel code to serial code. Calculation circuit measures current from current code word by signal from converter and controls access unit for selection of respective word from set. Generator receives primary synchronization signal and outputs second synchronization signal and load pulse with frequency of primary synchronization signal divided by factor. Counter loads reference value and counts serial data in ascending or descending order. Detector checks equality or difference of read and reference values. Third memory unit stores previous input value if they are equal, and loads read value, if they differ. Comparator compares signal from third memory unit to reference signal and controls access unit. EFFECT: simplified measuring, independence from bit length. 5 cl, 29 dwg
