FADING SIMULATOR

摘要

A fading simulator for generating multipath-faded test signals which have attenuation notches of precisely controllable frequency position and attenuation depth from a modulated input signal of known bandwith. The input signal is fed to a splitter (10) that directs two in-phase components to a first path (14) and a second path (18). The input to each path is divided by a splitter (22) into in-phase and quadrature sub-signals (24 and 26) having a quadrature phase relationship, each sub-signal being fed to a respective inverting attenuator (28 and 32), the outputs of the attenuators then being combined in a combiner (36) and the combined output being passed through a variable delay line (16) to generate the output of the respective path. The outputs of each path are then combined in a combiner circuit (12) to generate the multipath-faded test signal. All four inverting attenuators are preferably substantially identical to one another so that the two paths have close to identical temperature-drift and other characteristics. The attenuators and delay lines are electronically controlled in tandem, preferably using a microprocessor and stored program, to generate precision, static or dynamic, attenuation notches desired.