| 摘要 |
An FM-FM audio multiplex unit for television broadcasting systems comprising a multivibrator type frequency modulator having a multivibrator for producing sub channel signals frequency modulated by audio sub channel signals, means for producing signals having double the frequency of horizontal synchronizing signals and an automatic phase controller for controlling the carrier frequency of the sub channel signals, the phase controller including a reference signal oscillator, first and second mixers for mixing the carrier signals in the sub channel signals and the signals having double the frequency of horizontal synchronizing signals with reference signals to obtain signals having high frequencies, first and second divider sections for dividing the frequencies of output signals from the first and second mixers to obtain signals having low frequencies and a phase detector for comparing the phases of output signals from the first and second dividers each other thereby making small the frequency variation of the horizontal synchronizing signals and the sub carrier signals, and resulting in causing the carrier signals of the sub channel signals to be synchronized with those having double the frequency of the horizontal synchronizing signals.
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