PURPOSE: To reduce the noise over a wide band by modulating the input signal through the modulator circuit comprising the free running multivibrator, giving the luminance modulation to the light emitting diode with the output of the modulator circuit and then transmitting the light through the optical system.
CONSTITUTION: The input signal obtained by converting the information signal from TV camera 1 or the TV wave from receiver 2 into the base band of the video received undergoes the pulse duration modulation (PWM) through modulator circuit 3 using the free running multivibrator. With this modulation signal, the luminance modulation is given to light emitting diode 4. The radiation light of diode 4 is changed into the parallel light through optical system 5 including the convex lens, the reflector and others to be then transmitted. This transmitted light is condensed by optical system 6 at a remote place to be converted into the electric signal through optical detector 7 such as the PIN diode, the APD and others. Then the input signal is reproduced at demodulator 8 to be displayed at picture receiver monitor 9. This signal process including the modulation and demodulation can be carried out in a digital way. Thus the deterioration can be reduced through the processes, and furthermore chrominance subcarrier can be transmitted without any disturbance since the carrier frequency is increased.
MORIFUJI MOTOYOSHI
TAKAHASHI AKIRA
INABA TATSUO
| JPS5246472A | 1977-04-13 | |||
| JP32008766A |
| US3258596A | 1966-06-28 |