| 摘要 |
PURPOSE:To obtain a wide dynamic range and to reduce the distortion, by providing a signal amplifier and a logarithmic compressor to add a logarithmic compressor output signal at an adder, and providing a phase compensating means among input signals to the adder among the input terminals of the adder from the signal amplifier. CONSTITUTION:An echo signal having a wide dynamic range as an input signal SI is inputted to a logarithmic amplifier 20. Delay lines are used for the 1st-3rd delay elements 17-19 and 6dB of attenuation is made to take matching to the atenuation of the signal. Further, the amplification corresponding to the 1st amplifier 8-the 4th amplifier 11 is made. Moreover, the delay time of a delay element 19 is set so that the signal phase fed to the logarithmic compressor 15 and the signal phase fed to a logarithmic compressor 14 and obtained through the delay element 19 for the output of the amplifier 10 can be coincided. Similarly, the delay elements 17, 18 set a delay time so that the input and the signal phase of the logarithmic compressor 15 are coincided at the input of logarithmic compressors 12, 13. The outputs of the logarithmic compressors 12-15 thus obtained are added 16 and outputted. |
