| 摘要 |
PURPOSE:To optimize the quantization level of an A/D converter by controlling the input amplitude level of the A/D converter according to the C/N ratio of a reception signal. CONSTITUTION:Power amplification 9 is performed and branching is performed for the reception signal for which a frequency conversion 10 is performed after via an AGC amplifier part 11. Subsequently, the both signals are multiplied by the local sine wave signal that a 90 deg. phase rotation is performed for the signal generated in a local sine wave signal oscillator 14 in a 90 deg. phase device 15 an the local sine wave signal for which the phase rotation is not performed in multipliers 12 and 13, the signals pass through LPF 16 and 17 and orthogonal base band signals are generated. Next, reception power is obtained by a detection part 18 by using these both signals. An AGC control part 24 calculates a C/N ratio by using signal power and reception power, outputs a control signal to the amplifier part 11 adjusting the input amplitude of A/D converters 19 and 20 according to the obtained C/N ratio, controls the A/D input amplitude to an optimum value and realizes the best error ratio characteristic. |
