| 摘要 |
1,023,742. Automatic frequency control systems. STANDARD TELEPHONES & CABLES Ltd. Dec. 6, 1963 [Dec. 8, 1962], No. 48257/63. Heading H3A. A frequency control voltage is applied over an amplifier to the junction of two series capacitor diodes equally back - biased by a constant voltage from a Zener diode 7 so that the capacities vary in opposite and equal direction but are unaffected by supply voltage variations. A switch 16 connects alternately diode 8 or 7 to a local oscillator circuit and is changed over whenever a frequency range switch alters the local oscillator frequency between values above and below an incoming received frequency. Alternatively the frequency controlled oscillator may be part of a transmitter receiver. The diodes 8, 9 may be in series with resistors 10, 11. |
