JPS63129360U - - Google Patents

Description

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the present invention.
FIG. 2 is a block diagram of a conventional voice switch type hands-free terminal, FIG. 3 is a timing diagram of each part in FIG. 2, and FIG. 4 is a block diagram of each part in FIG. 1: Receiving terminal, 2, 7: Variable attenuator, 3: Receiving terminal, 4, 9: Signal detection circuit, 5: Comparison circuit, 6
: Transmission terminal, 8: Transmission terminal, 10: Delay circuit.

Claims (1)

[Scope of utility model registration request] a first variable attenuator that attenuates or does not attenuate the signal on the reception signal path and outputs it to the receiving end; and a second variable attenuator that attenuates or does not attenuate the transmission signal and outputs it to the transmission signal path. , a delay circuit that delays a received signal on a receiving signal path, a first signal detection circuit that detects an output signal of the delay circuit and outputs a signal according to its level, and an output signal of the second variable attenuator. A second signal detection circuit detects the signal and outputs a signal according to the level, and compares the output signals of the first and second signal detection circuits, and uses the comparison result to detect the first and second signals. A hands-free terminal comprising a comparison circuit that controls the amount of attenuation of a variable attenuator.