Patent ID: 7451472
Filing Date: 2008-11-11
Classification: H04N

Abstract:
1. A method for testing a non-symmetrical network comprising: providing said non-symmetrical network having a distribution point, a first direction of transmission operating at a first frequency, and a second direction of transmission operating at a second frequency, said first direction of transmission corresponding to a downstream direction of transmission operating at said first frequency that is a higher frequency than said second frequency, said second direction of transmission corresponding to an upstream direction of transmission operating at said second frequency that is a lower frequency than said first frequency, and said upstream direction of transmission having larger impairments than said downstream direction of transmission; connecting a test apparatus having a cable modem termination system (CTMS), an input to said non-symmetrical network, an output to said non-symmetrical network, at least one cable modem, a diplex filter, and an upconverter having an input and an output at said distribution point of said non-symmetrical network such that said test apparatus output is connected to said first direction of transmission that corresponds to said downstream direction of transmission through a combiner device, said test apparatus input is connected to said second direction of transmission that corresponds to said upstream direction of transmission through a splitter device, said cable modem connects to said CTMS and said upconverter input through said diplex filter, said CTMS connects at said input of said test apparatus to said upstream direction of transmission, and said upconverter output connects at said output of said test apparatus to said downstream direction of transmission; connecting a loopback device having an input and an output to said non-symmetrical network at a remote location from said distribution point such that said loopback device input is connected to said first direction of transmission operating at said first frequency and said loopback device output is connected to said second direction of transmission operating at said second frequency; creating a test signal in said test apparatus; transmitting said test signal from said test apparatus to said loopback device through said test apparatus output on said first direction of transmission operating at said first frequency; receiving said test signal on said first direction of transmission at said loopback device input at said first frequency; transforming said test signal from said first frequency operating at said higher frequency of said downstream direction of transmission to said second frequency operating at said lower frequency of said upstream direction of transmission in said loopback device operating as a downconverter device; transmitting said test signal from said loopback device output to said distribution point on said second direction of transmission operating at said second frequency; receiving said test signal on said second direction of transmission at said test apparatus input connected to said second direction of transmission and operating at said second frequency; and performing at least one analysis measurement test on said test signal.