Abstract: Ingress noise labeling tags are coupled into the signal path at various nodes of a cable network. The tags imprint a unique electric signature into a local ingress noise, making the noise identifiable at the headend of the network. In one embodiment, tags do not require external control signals to operate, the electrical response of the tags being determined by present and/or past magnitudes of the return path signal. Advantageously, such tags can be made entirely passive, not requiring a control signal or an external source of electrical power.