Carrier suppression modulating circuit |
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| 申请号 | JP9603879 | 申请日 | 1979-07-30 | 公开(公告)号 | JPS5620309A | 公开(公告)日 | 1981-02-25 |
| 申请人 | Nec Corp; | 发明人 | ONODERA TAKEO; | ||||
| 摘要 | PURPOSE:To make it possible to minimize automatically the leakage of a carrier by constricting the heater resistance value of the indirectly-heated thermistor of a leakage adjusting circuit to a resistance value when a leakage carrier shows its minimum value. CONSTITUTION:While a carrier is supplied to input 11, a signal wave is supplied to input 12 and their outputs are supplied to modulating circuit 21. The output of circuit 21, after having a carrier leakage component selected by BPF22, is sent to and amplified by amplifier 23 up to a required level and then phase-compared to a carrier from input 11 by phase detector 24. Output Ec of detector 24 has a DC component compared to reference voltage Er by comparison amplifier 25, whose amplified output P is applied to the heater of the indirectly-heated thermistor of carrier leakage adjusting circuit 26, bringing its resistance under control. Here, the resistance value of the thermistor is constricted to a resistance value when the leakage carrier shows its minimum value, so that the carrier leakage can be minimized automatically. | ||||||
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| 说明书全文 | |||||||
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