Analysis of Captured Random Data Signals to Measure Linear and Nonlinear Distortions

摘要

A method to capture random data signals at an end point in a broadband network and process them via digital signal processing (DSP) techniques to determine both linear distortions and nonlinear distortions. In a distribution network, such as a tree and branch cable network, the location of the impairment addition can be identified by determining location of terminals have a distortion and locations of terminals that do not have a distortion. Linear distortions may be determined by an autocorrelation of the captured signal with itself. Nonlinear distortions may be determined by processing measured energy in a vacant band with manufactured energy in the vacant band. If a vacant band is not available, one can be created by demodulating a signal occupying the band, and subtracting the demodulated signal from the measured signal plus interference in a band, leaving only the interference.

主权项

1. A method for determining the presence of nonlinear distortion in a signal transmitted from a source and received at a site comprising:
capturing first samples of the signal received at the site, said first samples having a bandwidth; making a measured signal from energy measured in a vacant bandwidth within the bandwidth of said first samples; removing from said first samples energy in said vacant bandwidth to create second samples; nonlinearly distorting said second samples; creating a manufactured signal using energy in said vacant bandwidth in said second samples; processing said measured signal and said manufactured signal to measure nonlinear distortion in the signal received at the site.