Patent ID: 8513952
Filing Date: 2013-08-20
Classification: G01R,H04L

Abstract:
1. A cable tester coupled to a cable having a cable length, comprising: a clock generator configured to generate a clock signal having a data symbol period; a clock divider configured to divide the data symbol period to generate a training signal having an adjustable clock period that is a multiple of the data symbol period; a signal generator, coupled to the cable, configured to inject a training signal that is synchronous with the clock signal into the cable; a receiver configured to sample a returned signal from the cable and adaptively filter the returned signal based on the training signal; and a controller, coupled to the clock generator, configured to determine the cable length based on a plurality of adaptive filter tap coefficients, the controller further configured to transform the adaptive filter tap coefficients to a frequency domain by a Fourier transform unit, determine a phase response based on the transformed adaptive filter tap coefficients, and determine a round-trip delay from a differentiation of the phase response with respect to a radian frequency.