Interpolation filter and method for switching between integer and fractional interpolation rates
US6275836A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jun 12, 1998 |
| Grant date | Aug 14, 2001 |
| Priority date | — |
| Expiry date | Jun 12, 2018 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03H17/0685
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
A voice or data transmission system and specifically an interpolation filter used within the transmission system is provided for producing either fractional or integer interpolation ratios. The digital signal resulting from the interpolation filter has a relatively high signal to noise ratio whenever fractional interpolation is needed. The interpolation filter includes multiple stages coupled in series, and an integer interpolation branch switched in parallel with a fractional interpolation branch. A controller determines whether the integer or fractional interpolation ratio is needed based on maintaining a fixed oversampling data rate from the interpolation filter given a changing incoming sampling rate. If the incoming sampling rate should require fractional interpolation, then a branch implementing fractional interpolation ratio is used in lieu of the integer interpolation ratio. A comb filter is preferably introduced within the fractional interpolation branch to attenuate imaging tones within the baseband of interest. An interpolation rate change switch used by the comb filter beneficially moves the imaging tones further away from the baseband so that minimum imaging noise is i…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.