| 摘要 |
<p>An RFI canceller, for use in a subscriber line system using multi-carrier modulation, measures an RFI disturbance in carriers falling within a band of frequencies causing the RFI. The RFI ingress into carriers outside the band of frequencies is estimated, and an error correcting signal derived from the estimation of the RFI ingress is subtracted form a received signal. The subscriber line system may be a VDSL system and said multi-carrier modulation may be DMT. The RFI canceller includes: a demodulator for demodulating an incoming data stream to provide a first parallel data stream; a parallel to serial convertor for converting the first parallel data stream to a first serial data stream; a digital to analogue convertor for converting said first serial data stream to a first analogue signal; an analogue RFI canceller circuit for combining the analogue signal with an analogue error correcting signal, to produce a second analogue signal; an analogue to a digital convertor for converting the second analogue signal to a second serial data signal; a serial to parallel convertor for converting said second serial data stream to a second parallel data stream; a modulator for modulating the second parallel data stream onto a multiplicity of carriers; and a digital RFI canceller for performing the operations outlined in the first paragraph of this abstract.</p> |
