| 摘要 |
<p>1308877 Automatic equalizers STANDARD TELEPHONES & CABLES Ltd 23 Sept 1971 44392/71 Heading H4R In a variable equalizer, e.g. for compensating ambient temperature dependent changes in frequency response in a line transmission system, the input signal is fed to two parallel connected circuits each comprising a frequency dependent impedance and a transistor. The output signal is derived from an electrode of one of the transistors and a control signal is arranged to control the ratio of the resistances presented by the two transistors, to vary the current distribution between them and thus change the frequency response of the circuit. As shown the input signal I is applied to a transistor T3 whose collector is connected to the parallel circuits formed by transistors T1 and T2 and frequency dependent impedances Z1 and Z2. The output is taken from the collector of T2 and the impedances of the transistors T1 and T2 are differentially varied by varying the control voltages CV1 and CV2 applied to their bases. The control voltages can be derived by peak detection of the output signal 0 of the circuit. The frequency dependent networks can be formed by three parallel connected arms containing respectively a resistor, a resistor and a capacitor in series, and a capacitor.</p> |
