FIELD: logging technology to measure physical properties of underground formations. SUBSTANCE: method employing this system includes preliminary detection signal processing in down-hole processor to determine time of arrival of acoustic wave into receiver and to transmit to surface arrival time alone. Down-hole logging instrument for acoustic logging and logging system utilizing it has control unit to control generation and reception of acoustic wave which incorporates analog-to-digital converter to convert detection signal to digital form with specified discretization interval, first storage to store received digital signal, second storage to store program of processing of stored digital signal and microprocessor meant to realize program stored in second storage in order to determine time of arrival of acoustic wave generated by generator and arrived into receiver while processing digital signal stored in first storage. EFFECT: enhanced operational reliability of system. 11 cl, 11 dwg
