Common mode choke

A cable distribution system with devices for attenuating noise propagating upstream from multiple subscriber sites toward a head end, the noise attenuating devices including a distributed cable modem filter and comprising:

• plural subscriber sites served by a cable distribution system node and plural nodes served by a cable distribution system head end;
• each subscriber site including an AC mains powered modem interconnected with the node via a coaxial cable and each node interconnected with the head end via an optical fiber;
• a modem transceiver receiving a broadcast signal originating from the cable distribution system and transmitting a signal to one of a television front end and a computer;
• within a modem housing a switching power supply receiving AC mains power via an EMI filter and digital electronics receiving a switching power supply output via an LC filter for filtering noise at a switching power supply frequency;
• and,
• external to the modem housing and integrated with the coaxial cable, a discrete component filter for filtering noise at harmonics of the switching power supply frequency, the noise carried by one or both of the coaxial shield and the coaxial center conductor;
• wherein the discrete component filters used with respective modems at subscriber sites protect the head end from switching power supply harmonic noise otherwise aggregated by the nodes and passed to the head end.