A return path system includes inserting RF packets between regular upstream data packets, where the data packets are generated by communication devices such as a computer or internet telephone. In one embodiment, the nanoparticle is a \u201csurfactant-free\u201d nanoparticle in which the surfactant moiety is covalently attached to the backbone of the polymer. Smoothed versions of the estimated attributes are calculated in accordance with a predetermined set of criteria are calculated. The detecting signal output terminal is connected to the bus switch and a trigger pin of the master device.