Amateur Radio Interference to VDSL2 is as old as the NBN

Mitigating Amateur Radio Interference to VDSL2 is a challenge most of us face unless you’re lucky enough to be area serviced by fibre. This document published in March 2022 by NBN Co finally explains the link between frequencies used by amateur radio operators – 80 and 40m, and the VDSL2 standard. It even speaks of notching these frequencies.

The introduction reads… This document is intended for technically-minded users or those providing technical support to users connected to the nbn™ network who are experiencing signal interference between their nbn™ service and amateur radio transmissions. It is assumed that the people referencing this document will have a reasonable understanding of electronics, wireless transmission and broadband transmission technology including digital subscriber line (DSL) and very high-speed DSL (VDSL).

The document is suitable for licensed cablers, telecommunications network technicians, operational support staff, network engineers and amateur radio operators. – Hey, that’s us!

The PDF can be downloaded from the NBNco website. You’ll also find plans for a simple 40m notch filter on this site.

The actual frequencies used by a VDSL2 service are not set in concrete but are selected by the node and modem in collaboration from the set of all possible tones between about 20KHz and 17MHz. The choice about which frequencies to use is based on, among other things, the one-off prevailing noise levels that the modem and node measure immediately prior to the modem and DSLAM achieving a synchronisation state or ‘coming into sync’.