Voice compressor circuit for transmitter modulator - has delay circuit and attenuator controlled by series connected attenuator and detector circuit

摘要

The circuit has an input coupled through a low pass filter (2) and amplifier (3) to a delay circuit (5) such as type Reticon SAD 1024, a variable attenuator (4), a further amplifier (12), and low pass filter (13) and then to the circuit output. The first amplifier output is also coupled to a series connection of a second variable attenuator (6), amplifier (10) and detector (9) whose output is connected to the control inputs of the two attentuators. The time constant of the detection circuit is equal to the delay time of the delay circuit. This avoids the response inertia normally present in such compressor circuits due to the detector delay. The device can be associated with a speech/noise discriminator, commanding the output signal cut-out of the compressor during periods of inactivity to avoid the rise of noise during long pauses.