The circuit component that makes possible 2W-4W operation is the
The most critical action that is taken to prevent singing in a long-
lines 2W-4W telephone circuit is the adjustment of the
Echo suppressors in a communication system operate on the principle
of voice switching.
When one of the communicating parties speaks
into his microphone, this echo suppressor acts to
balance the hybrid.
disable the receiving circuit.
control the equalizer to compensate for echo.
switch a send line amplifier into the circuit to overcome loss.
Assume that the input to an amplifier is 2 dBm and the output is 20
dBm. The gain of the amplifier is