Digital device and method for filtering, decimation and transposition into distributed baseband and corresponding digital modulator
US6487221B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Oct 5, 1998 |
| Grant date | Nov 26, 2002 |
| Priority date | — |
| Expiry date | Oct 5, 2018 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03D7/161
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
The invention relates to apparatus for filtering, decimating and transposing into baseband, the apparatus being of the entirely digital type, and serving both to extract and transpose into baseband one of the channels, referred to as the “channel of interest”, of a frequency multiplex of channels, and also to reduce the oversampling factor of said channel of interest, each channel being associated with a distinct carrier. The said apparatus comprising at least two stages in cascade (401 to 40L), each stage comprising filter means (42) and decimation means (43), said filter means being placed upstream from said decimation means and enabling a portion of the spectrum to be purged at locations where the decimation means produce aliasing. According to the invention, each stage (401 to 40L) also comprises transposition means (41) placed upstream from said filter means (42) and associated with a transposition frequency (ft,i) previously selected from a set of N possible distinct transposition frequencies so as to transpose the carrier (p0) associated with said channel of interest as close as possible to zero frequency.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.