| 摘要 |
PURPOSE:To send a voice signal as an optical signal with simple configuration by applying pulse width modulation to the voice signal at an optical frequency traced by an audible frequency, sending and receiving the pulse width modulation light, converting the light into an analog voice signal and demodulating the voice signal. CONSTITUTION:A voice signal inputted to a microphone 1 is converted into a rectangular pulse width modulation(PWM) pulse by a pulse width modulator 3 being a conversion means for a signal at an optical frequency band through an amplifier 2a. The PWM signal optical pulse subject to pulse width modulation is converted into an infrared ray light by an infrared ray light emission diode 4 being a transmission means through an amplifier 2b and sent in space. Then, the optical pulse sent through space is received by an infrared ray receiving element 5 being the light receiving means, demodulated into the original audible frequency voice signal by a low pass filter 6 being a demodulation means through an amplifier 2d and outputted as a voice via a speaker 7 or the like through an amplifier 2c. |
