| 摘要 |
PROBLEM TO BE SOLVED: To suppress increase of quantization noises and to prevent deterioration of the error rate characteristic by providing a system to expand the amplitude of the digital signal which is converted with the reverse input/output characteristic nonlinear against a compressor. SOLUTION: The modulated wave of an IF band that is inputted from a terminal 1 is transmitted through a variable gain amplifier 11 and detected by a demodulator 12. Thus a base band analog signal is outputted and undergoes the limitation of amplitude via a compressor 13. Then the compressed signal undergoes the A/D conversion via an A/D converter 14. This converted digital signal is inputted to an expander 15 which attains the input/output characteristic inverse to that of the compressor 13. Thus the amplitude of the digital signal is expanded. An equalizer 16 inputs the expanded and restored base band digital signal to equalize the inter-code interference component and outputs an equalized signal through a terminal 2. A control circuit 18 detects the output signal of a multiplier or the reference value of a reference signal point and controls the gain of the amplifier 11 to set the output signal or the reference value at 0. |
