| 摘要 |
PURPOSE:To confirm the level of a receiving level with eyes by dividing the receiving level detected by a level detection circuit according to prescribed plural level standards, outputting a respective division signal, and indicating it by an electric lamp indication correspondingly to the respective division signal, when the carrier detection signal of a MODEM is outputted. CONSTITUTION:When the MODEM 1 receives the modulated input signal of an input terminal A, the carrier detection signal of a carrier detect terminal CD is turned on, and a control circuit 13 makes the output of a preamplifier 7 effective. The input signal of the input terminal A is amplified by the preamplifier 7, and the receiving level of it is detected by the level detection circuit consisting of a diode 4, a capacitor 5 and a resistor 6. Then, it is level-adjusted by an amplifier 8, converted into a digital signal by an A/D converter 9, and decoded by a decoder 10. When the receiving level at the input terminal A is comparatively high and of an adequate level, a green light emission diode D1 is lit. When the level is low, the red light emission diode D3 is lit. |
