WAVE DETECTOR FOR TELEVISION SOUND

摘要

PURPOSE:To prevent the deterioration of the aural signal with a simple constitution, by compounding the signal obtained by giving a -90 deg. phase shift and attenuation to the aural IF signal and the signal obtained by giving a +90 deg. phase shift and amplitude limit amplification to the aural signal and furthermore compounding this composite signal and the aural IF signal to cancel the phase modulating caused by the video carrier wave. CONSTITUTION:The TVIF signal delivered from a mixer is amplified by the amplifier 5 and then applied to the -90 deg. phase-shift attenuator 6 to deliver the T1' vector to the output of the attenuator 6. At the same time the IF signal is applied to the limiter amplifier 7 which gives a +90 deg. phase-shift amplification and amplitude limit to deliver the T1'' vector to the output of the amplifier 7. These T1' and T1'' vectors are added together at the adder 8 to deliver the T1''' vector from the adder 8. Furthermore the T1 vector of the IF signal given from the amplifier 5 is added with the T1''' vector given from the adder 8 at the adder 9 to deliver the signal V2. Thus the phase modulation due to the video carrier can be cancelled to prevent the deterioration of the aural signal.