Fading simulator

(57) -- the multiplex way which has an attenuation notch which can control a frequency position and/or attenuation depth from the abnormal-conditions input signal of the bandwidth of summary known -- weakening -- the fading simulator for generating a test signal. An input signal is given to the splitter (10) which sends out two ingredients of an inphase to the 1st signal way (14) and the 2nd signal way (18). The input to each signal way is divided into the rectangular sub signal (24, 26) which has a rectangular phase relation by an inphase by a splitter (22), Each sub signal is given to each reversal attenuator (28), the output of an attenuator is compounded with a synthetic vessel (36), and a synthetic signal passes a variable delay line (16), and generates the output of each signal way. The output of each signal way is compounded in a synthetic circuit (12) -- a multiplex way -- weakening -- a test signal is generated. As for all the four reversal attenuators, it is desirable that it is mutually the same substantially so that it may become whether the character of a temperature drift and others is near, and the same. Ways / two / signal Electronic control of an attenuator and the delay line is carried out in a column, and they generate the precise, static, or dynamic attenuation notch desired using the program preferably remembered to be a microprocessor.