FIELD: monitoring fiber-optic restricted-access data transfer systems using quantum noise method.
SUBSTANCE: proposed method includes generation of optical transmission signal incorporating dc optical radiation and data signal, transmission of optical signal over fiber-optic line, reception, detection, amplification, and separation of data signal and fixed level, and check-up for variations in inserted loss. Pending transmission check signal is introduced in optical signal and upon reception and detection it is separated and its amplitude is compared with threshold level found in advance from proposed formula. Attempt of reading information off fiber-optic transmission line is recognized by reduction of check signal amplitude relative to threshold level.
EFFECT: enhanced probability of detecting attempt of reading information off fiber-optic line; reduced malfunction probability.
1 cl, 2 dwg
