| 摘要 |
Disclosed is a circuit for automatic dynamic compression and/or expansion. The circuit has an adjusting member for varying the propogation constant in a useful signal path and a further similar adjusting member for varying the propogation constant in a branch path which serves for deriving a control voltage which is applied to the control inputs of the adjusting members in the useful signal path and in the branch path. Further the circuit has a lowpass circuit which is connected to the adjusting member located in the useful signal path. The circuit can be changed over to a different compander characteristic when the adjusting member located in the useful signal path is connected up as a controllable highpass. The limiting frequency is of the order of magnitude of the limiting frequency of the lowpass circuit. The highpass can be formed by a capacitor in series with the adjusting member in the useful signal path and the highpass function for low frequencies can be limited by a resistor in parallel with the adjusting member and the capacitor. The limiting frequency of the lowpass circuit is reduced by an additional capacitor in parallel with the capacitor already provided. In both operation modes, the same voltage generator is used for controlling the adjusting member in the useful signal path. |
