| 摘要 |
PURPOSE:To detect the transmission state in a high speed, by detecting an error between a transmission signal and a discriminating value, applying a detection signal to an automatic variable gain amplifier keeping an output power to a con stant value, and observing the average output of an incoming signal in error depending on a gain control signal of the amplifier. CONSTITUTION:An error signal detecting an error between a reception signal an its discriminating value at error detectors 6'', 6''' is applied to automatic variable gain amplifiers 7, 7'. The amplifiers 7, 7' consist of a variable gain amplifier 70, a detection circuit 71 obtaining the absolute value of the output, subtractor 72 comparing the detected output with a voltage of a battery 73, and a low pass filter 74 smoothing the output. An output 701 of the filter 74 becomes a signal controlling the gain. Since the signal of the output 701 is increased in response to the increase in the error signal, the reception state can be monitored by observing the signal. Thus, the transmission state can be detected in a high speed without requiring complicated circuits. |
