| 摘要 |
<p>The invention concerns an entirely digital device for filtering, decimation and transposition into baseband for extracting and transposing in baseband one of the channels, called useful channel, of a channel frequency division multiplex and for reducing the oversampling factor of said useful channel, each channel being associated with a different carrier. This device comprises at least two rippling stages (401 to 40L), each stage comprising filtering means (42) and decimation means (43), said filtering means being located upstream of said decimation means for cleaning part of the spectrum in the places where the decimation means produce spectrum aliasing. The invention is characterised in that each stage (401 to 40L) further comprises transposing means, located upstream of said filtering means (42) and associated with a transposition frequency (ft,i), previously selected among a set of N possible different frequencies, so as to transpose nearest to the zero frequency of the carrier (p0) associated with said useful channel.</p> |
