Patent ID: 8325613
Filing Date: 2012-12-04
Classification: H04L

Abstract:
1. A testing device for determining a phase response in an upstream transmission path of a communication network, comprising: a coupler for sending and receiving broadband RF signals to and from the communication network; a cable modem circuit for generating an RF transmission signal to request an IP address from a remote cable modem termination system disposed at a headend of the communication network, and for receiving IP connection information from the cable modem termination system, including pre-equalization coefficient information relating to the transmission path between the testing device and the cable modem termination system, wherein the pre-equalization coefficient information is generated at the headend by the remote cable modem termination system; and a processing circuit connected to the cable modem circuit for receiving the pre-equalization coefficient information from the cable modem circuit, and for determining the phase response of the transmission path from the remotely obtained pre-equalization coefficient information, wherein the pre-equalization coefficient information includes adaptive equalizer coefficients, and wherein in operation, the processing circuit performs: a discrete Fourier transform of the adaptive equalizer coefficients; and an inversion operation of a result of the discrete Fourier transform, to determine the phase response of the upstream transmission path.