Patent ID: 9647851
Date: 2017-05-09
CPC Classifications: H04L,H04N

Claim:
1. A network interface device for connecting subscriber equipment to a cable television (CATV) network over which downstream signals in a first frequency band from a headend of the CATV network are transmitted to the subscriber equipment and valid upstream signals in a second different frequency band are transmitted from the subscriber equipment to the headend, the network interface device having an upstream noise mitigation circuit which mitigates ingress noise into the CATV network in the second frequency band, comprising: an upstream filter which filters upstream signals before delivery to the CATV network, the upstream signals including a plurality of frequencies; a detector connected to the upstream filter wherein the detector determines a level of power corresponding to the upstream signals filtered by the upstream filter, and wherein the detector supplies a power signal proportionate to the power level of the upstream signals; a threshold circuit which establishes a threshold level of power which characterizes valid upstream signals, and which supplies a threshold signal related to the established threshold level of power; a comparator connected to the detector and the threshold circuit which compares each power signal to the threshold signal, and which asserts a trigger signal when one of the power signals exceeds the threshold signal; a switch connected to the upstream filter wherein the switch is configured to change from a normal position to an activated position, the normal position isolating and terminating the upstream signals from the upstream filter, and the activated position conducting the upstream signals from the upstream filter to the CATV network, wherein the conducted upstream signals include information; a control circuit configured to assert a control signal in response to the trigger signal, the control circuit comprising a timer receptive of the trigger signal and operative to assert a timing signal for a time period commencing upon the assertion of the trigger signal, wherein the detector, the threshold circuit and the comparator operate without demodulating the frequencies within the upstream signals; wherein the switch is changed to the activated position in response to the comparator's determination that power level of the upstream signals exceeds the power of the threshold signal for the duration of the time period, wherein the threshold circuit and the comparator operate instantaneously without demodulating, analyzing, comparing or isolating any of the frequencies within the upstream signals; and wherein the switch returns to the normal position after the information has been transmitted to the CATV network.