Abstract: 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 bandwidth. The input signal is fed to a splitter that directs two in-phase components to a first path and a second path. The input to each path is divided by a splitter into in-phase and quadrature sub-signals having a quadrature phase relationship, each sub-signal being fed to a respective inverting attenuator, the outputs of the attenuators then being combined in a combiner and the combined output being passed through a variable delay line to generate the output of the respective path. The outputs of each path are then combined in a combiner circuit 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.

Abstract: The present invention provides a method and apparatus for evaluating the performance of a signal-processing device during a test period when an input signal is applied to the signal-processing device and an output signal is generated by it. A select profile of the input (or output) signal quality is derived at intervals in which the output (or input) signal lies within some predetermined range. The derived profile may be normalized with respect to the quality of the input (or output) signal throughout the test period. The profile is indicative of device performance of the device being tested. The method may be implemented in either hardware or software.