| 摘要 |
<p>RCA 76373/76373A In a signal expander, the envelope of an input signal to be expanded is detected and applied as a control signal to the gain control input of a variable gain device which expands the input signal. The control signal is applied to the variable gain device via an adaptive filter having improved ripple reduction and transient performance characteristics to minimize audibility of gain changes. The adaptive filter includes a low pass filter for producing a smoothed control signal essentially free of ripple and an analog gate for coupling the greater of the smoothed signal or a further signal to the variable gain device, the further signal being equal to the detector output signal less a constant. Compression of an input signal is provided applying the input signal to the non-inverting input terminal of an amplifier and coupling the (compressed) output signal of the amplifier to its inverting input terminal via the expander.</p> |
