| 摘要 |
FIELD: safety systems.SUBSTANCE: invention relates to detection of prohibited objects and identification of their carriers in stream of people, alternately crossing curved metal detector opening. Summary: probing signal is emitted in form of short pulses sequence with high porosity. Receiving reflected signal by two pairs of receiving coils installed at height hand hin left and right arched postsrespectively. From output signals of S(t)and S(t) of first and second S(t) receiving coils and output signals S(t)and S(t) of third and fourth receiving coils gradiometric signal S(t)=S(t)-S(t) is formed. Arched signal S(t)=S(t)-S(t) is formed. Frequency filtration and time selection of arched signal S(t) are performed, followed by extraction of instantaneous values of its amplitude A(t). Floating threshold P(t) is formed by averaging A(t) on interval (t-T;t), where T is time allocated for monitoring of one face in flow. Forbidden object carrier is determined as person crossing arched opening at moment A(t) of threshold P(t) exceeding.EFFECT: high noise immunity of arch-pulse metal detectors relative to external interference generated by remote radio-frequency sources.1 cl, 3 dwg |
