Adaptive multiple sub-band common mode RFI suppression.

Abstract

Currently, the presence of significant RE noise on twisted pair loops prevents mass deployment of high-speed Digital Subscriber Loop (DSL) technology. DSL technology generally uses bandwidth within the frequency spectrum range of 10 kHz up to 10 MHz. Unfortunately this same spectrum is presently allocated for private, governmental and public radio communications. As well, due to limited cable balance, twisted pair copper cables are highly susceptible to ingress from noise sources present within the DSL frequency bandwidth. This thesis presents a new architecture to reduce radio frequency interference (RFI) noise at the receiver by exploiting the transmission characteristics of twisted pair wire. A novel technique is proposed in this thesis to reduce common-mode noise coupled into the differential mode signal of a twisted pair cable, by adding an identical but inverted version of the common mode signal component. The resulting signal is the differential mode signal without the common mode RFI noise. Simulations using Matlab shows that this technique can reduce RFI by as much as 38.7 dB.