Forward-backward channel interpolator
US6173011A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | May 28, 1998 |
| Grant date | Jan 9, 2001 |
| Priority date | — |
| Expiry date | May 28, 2018 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04L2025/0349
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
An interpolator having a linear phase response has a first stage implemented with an IIR filter to achieve the narrow transition bandwidth with relatively few filter coefficients. Zero-stuffing and filtering are used to achieve the interpolation. A forward-backward filtering methodology is then used to achieve a linear phase response for the IIR filter. The input sequence to be interpolated is zero stuffed and passed through the IIR filter a first time. Then the time order of the resulting sequence is reversed and then passed through the IIR filter a second time. After that, the resulting output sequence is reversed again. Guard blocks are added to both ends of the input sequence, and then a block of zeros is appended to the zero-stuffed guarded input sequence. The appended zero block causes the startup and ending transient effect of the IIR filter's step response to be equal at both ends, which tends to improve the accuracy of the interpolation. Subsequent zero-stuffing and filtering by FIR filter stages are used to further increase the interpolation. A linear interpolator may also be included after the FIR filter stages.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.