Patent ID: 6094211
Filing Date: 2000-07-25
Classification: H04N

Abstract:
A subscriber subsystem for use with a cable TV system, said cable TV system having a headend from which downstream signal emanates and to which an upstream signal is directed and a shared bidirectional subsystem connected to said headend and extending downstream therefrom to conduct both downstream and upstream signals, said downstream signal being in a first band and said upstream signal being in a lower second band wherein the lowest frequency of said first band is higher than the highest frequency of said second band, said subscriber subsystem connected to said shared bidirectional subsystem downstream from said headend to receive said downstream signal and to add a user initiated upstream signal to said shared bidirectional subsystem, said subscriber subsystem comprising:a drop cable connected to said shared bidirectional subsystem and extending downstream therefrom;an ingress noise blocker serially connected with said drop cable at a selected point there along, said ingress noise blocker having:a first high pass filter having a cut-off frequency that is lower than said lowest frequency of said first band and higher than said highest frequency of said second band to pass said downstream signal and block said upstream signal; anda bypass section connected in parallel across said first high pass filter, said bypass section including:a pair of low pass filters each having a cut-off frequency that is lower than said lowest frequency of said first band, higher than said highest frequency of said second band, and lower than said cut-off frequency of said first high pass filter to pass said upstream signal and to block the transmission of visible switching noise artifacts and said downstream signal; anda remotely operable attenuator serially connected intermediate said pair of low pass filters to pass upstream signals following receipt of a remote control signal; anda subscriber facility connected to a downstream end of said drop cable to receive said downstream signal therefrom, to generate and present said upstream signal to said drop cable, and to generate and apply said remote control signal to said drop cable to activate said remotely operable attenuator prior to presenting said upstream signal to said drop cable;wherein said remote control signal has a frequency that is lower than the lowest frequency of said second band, begins before said upstream signal is presented to said drop cable and lasts at least until said upstream signal terminates.