Patent ID: 7617517

Claim:
A cable modem comprising: a Central Processing Unit (CPU) adapted to output a control signal to perform different high-pass filtering depending on frequency bands of upstream signals transmitted to a Hybrid Fiber Coaxial (HFC) network, with the control signal depending on a frequency band for upstream transmission that the Cable Modem Termination System (CMTS) has transmitted; the CPU inputting upstream signals to a multiplex High-Pass Filter; the multiplex High-Pass Filter (HPF) adapted to filter the inputted upstream signals through different paths based on their respective frequency bands, wherein the multiplex HPF includes a first HPF and a second HPF, the first HPF adapted to pass a frequency of at least 10 MHz to high-pass filter upstream signals having a frequency between 10 MHz and 20 MHz and the second HPF adapted to pass a frequency of at least 20 MHz to high-pass filter upstream signals having a frequency of at least 20 MHz; and a High-Pass Filter (HPF) selection unit adapted to select one of the first and the second HPFs included in the multiplex HPF in accordance with the control signal to pass the upstream signals through the different paths wherein the HPF selection unit is adapted to bypass the upstream signals so that upstream signals having a frequency between 5 MHz and 10 MHz are not filtered.