Compression/decompression for preservation of high fidelity speech quality at low bandwidth
US5822370A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Apr 16, 1996 |
| Grant date | Oct 13, 1998 |
| Priority date | — |
| Expiry date | Apr 16, 2016 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG10L25/51
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
The input signal is filtered by bandpass filters having different passbands. These filtered signals are input to power detectors that average the power present in each band. A comparator compares each power level signal to a predetermined power threshold to determine if information is present in any of the bands. If information is present in the upper bands, the information is transformed by a discrete wavelet transform and is thresholded and then shifted to the lower bands. The process by which the shifting operation was accomplished is stored in a code book band. An inverse wavelet transform generates the compressed signal by transforming the signals from the wavelet domain to the time domain. If the signal was compressed, the code book signal is transmitted with the compressed signal to a receiving unit for decompression. If the signal was not compressed, the code book signal and the original input signal is transmitted to the receiving unit. The receiving unit receives the transmitted signal and reconstructs the original input from the transmitted signal, either directly or by re-spreading and transforming the compressed signal from the transmitted signal responsive to the code…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.