| 摘要 |
PROBLEM TO BE SOLVED: To realize an automatic gain control, regardless of the response characteristic of an amplifier for gain control and to enable a high speed convergence. SOLUTION: A reception signal is added to an A/D converter 2A through an amplifier 1A for gain control. In an amplitude detector 3A, the size of the amplitude of the output signal of the A/D converter 2A is detected and whether the size of the amplitude is within a set range or not is detected by a comparator 4A. In the detection result of the comparator 4A, a count up is performed by a counter 5A till the size of the amplitude becomes within the set range. When the size of the amplitude becomes within the set range, the output value of the counter 5A is held in a hold circuit 6A. When the size of the amplitude becomes within the set range, a reference value is subtracted from the size of the detected amplitude by the amplitude detector 3 by a subtracter 7, the subtraction result is multiplied by a constant in a multiplier 8 A and the result is smoothened by an integrator 9A. In an adder 10 A, the output signals of the hold circuit 6 A and the integrator 9A are added and the signals are feedbacked as control signals to the amplifier 1A for gain control through a D/A converter 11A. |
