Title:
AUDIO SIGNAL DETECTOR
Document Type and Number:
Japanese Patent JPS63241318
Kind Code:
A
Abstract:
PURPOSE:To prevent an error that a sonic wave having a similar frequency component is judged to be an audio signal, by judging the stationariness of a specific frequency component from signal intensity and a continuous time length. CONSTITUTION:A sonic wave containing audio signal and traffic noise is converted to an electric signal 1a by an acousto-electric converter 1 to be inputted to band-pass filters 3A, 3B. Signals 3a, 3b obtained by extracting only preset frequency components from the electric signal 1a are outputted from said filters 3A, 3B and amplified by automatic gain controllers 2A, 2B to become signals S1, S2 which are, in turn, compared with reference voltages E1, E2 by voltage comparators 9A, 9B. The pulse train continuous times of the output signals U1, U2 of the voltage comparators 9A, 9B are measured by time measuring devices 10A, 10B and, when the signals U1, U2 continue for a predetermined time or more, output signals W1, W2 become '1'. A judge device 70 judges that an audio signal is inputted.
Inventors:
JINNAI NORIHIRO
Application Number:
JP7429087A
Publication Date:
October 06, 1988
Filing Date:
March 30, 1987
Export Citation:
Assignee:
MITSUBISHI ELECTRIC CORP
International Classes:
G01H3/08; A61F11/04; (IPC1-7): A61F11/04; G01H3/08
Attorney, Agent or Firm:
Soga Doteru