| 摘要 |
<p>System for connecting a plurality of digital subscribers to a data network, comprising a local part connected, by an optical fiber link, to a remote part. Said local part comprises a plurality of DSLAM line cards with xDSL over fiber transceiver that, in turn, comprise a plurality of xDSL lines comprising a modified analog front end which comprises an digital-analogue converter to transform a transmitted digital downstream signal into an analogue downstream signal; an oscillator which fixes an oscillation frequency for the xDSL line; a mixer, directly connected to the output to convert the analog downstream signal into the oscillation frequency; and a band pass filter centered at the oscillation frequency which filters the converted analog downstream signal. And in upstream direction: a band pass filter centered at the oscillation frequency which filters an analogue upstream signal; an oscillator which fixes an oscillation frequency for the xDSL line; a mixer, directly connected to the output of the band pass filter to convert the analogue downstream signal into the original frequency; a low pass filter to avoid aliasing; an analogue front end which comprises an analogue-digital converter to transform the converted analogue upstream signal into a digital upstream signal.</p> |
