Patent ID: 6724177
Filing Date: 2004-04-20
Classification: G01R

Abstract:
A method of obtaining a measurement signal from a communications signal, the method comprising:applying a comparatively low-rate periodic modulation pattern to a carrier signal to form an input signal; using a communications signal amplifier to amplify the input signal, thereby producing a communications signal exhibiting distortion due to impairments of the communication signal amplifier; down-converting the communications signal to produce a comparatively low-rate intermediate-frequency signal; and conditioning the intermediate-frequency signal to produce a measurement signal representing the communications signal, including amplifying the intermediate-frequency signal using a video amplifier, the measurement signal exhibiting distortion due to impairments of the video amplifier; wherein the measurement signal occupies a frequency bandwidth centered about a center frequency that is many times the frequency bandwidth, and distortion due to impairments of the communication signal amplifier is spectrally separated from distortion due to impairments of the video amplifier.