Patent ID: 8624654

Claim:
An automatic step variable attenuator comprising: a step variable attenuator attenuating a received signal of an electric wave signal in an attenuation amount corresponding to a control signal in a step-like style; a detector disposed in parallel with the step variable attenuator for input of the received signal of the electric wave signal, and converting an electric power of the received signal thus inputted into an intensity signal representing an intensity of the received signal; and a comparator portion generating the control signal corresponding to a result of comparison for differences between the intensity signal obtained from the detector and plural threshold values, and outputting the control signal thus generated to the step variable attenuator, wherein the comparator portion includes plural comparators comparing thresholds whose values are different from one another in the step-like style, and the intensity signal with one another, and carries out a comparing operation in such a way that an output signal is inverted from the comparator comparing a lowest threshold for comparison start, and the intensity signal with each other, and the lowest threshold of the comparator whose output signal is inverted is switched over to a threshold lower than the threshold which is used in first comparison.