发明名称 CONTROL SIGNAL DISCRIMINATOR IN VOICE MULTIPLEX BROADCASTING RECEIVER
摘要 PURPOSE:To remove the influence slight displacement in the tuning frequency of the filter by using a filter generating change in the transmission phase characteristics at substantially intermediate frequency of both the modulated frequencies in order to detect the modulated frequency of the control signal. CONSTITUTION:The rectifying output voltage level of the control signal (b) is discriminated by the comparison switching circuit 21 to obtain the change-over signal (m). The amplitude detector 4 of output (c) is fed to the filter circuit 22 generating the change in transmission phase charactristics between 922 5Hz and 982, 5Hz, thereby the change over signal (n) for discriminating whether the modulated frequency is 922.5Hz or 982.5Hz. These two change-over signals (m), (n) are fed to the change-over switch circuit 13 to operate the desired control signal discrimination and when the level of the control signal does not reach the predetermined level, it is enforcibly monoral operated. Accordingly, if there is change slightly in the filter characteristics, both the modulated frequencies can be effectively discriminated.
申请公布号 JPS5550786(A) 申请公布日期 1980.04.12
申请号 JP19780123815 申请日期 1978.10.06
申请人 MITSUBISHI ELECTRIC CORP 发明人 YAZAWA NOBUHARU;KATOU KIKUO
分类号 H04N5/60 主分类号 H04N5/60
代理机构 代理人
主权项
地址