Method for transmitting an audio signal with an improved signal to noise ratio
US5179623A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Mar 26, 1990 |
| Grant date | Jan 12, 1993 |
| Priority date | — |
| Expiry date | Mar 26, 2010 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04B1/665
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
A method of transmitting an audio signal wherein the audio signal is partitioned into successive (in time) blocks by means of time windows, the signal parts contained in the blocks are converted to short-time frequency spectrums by transformation, subsequently the short-time frequency spectrums are coded on the basis of psycho-acoustical masking laws and are transmitted. The received coded signals are decoded, the short-time frequency spectrum signals are brought back into the time domain through re-transformation, and finally the blocks present in the time domain are assembled. Moreover, the blocks are partitioned into sub-blocks and, in case of signal level changes from one block to the other which exceed a predetermined value, the signal parts in the sub-blocks are subjected to a compression prior to transformation and to a complementary expansion after the re-transformation. To improve the signal-to-noise ratio, the signal is amplified and/or attenuated in the sub-blocks during the compression dependent on the average signal powers in the respective sub-blocks.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.