Method and apparatus compensating for effects of digital loss insertion in signal transmissions between modems
US5724393A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Feb 17, 1995 |
| Grant date | Mar 3, 1998 |
| Priority date | — |
| Expiry date | Feb 17, 2015 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04B14/048
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
The present invention provides a method and apparatus for minimizing quantization noise in signal transmissions between modems coupled together via a digital network resulting from the performance of digital loss insertion in .mu.-law encoded signal transmissions when the receiving modem is coupled to the digital network via an analog subscriber loop. In a preferred embodiment, the minimization of quantization noise is effected by providing in a digital modem means for .mu.-law encoding and decoding of signal transmissions, means for scaling the amplitude levels of signals generated by the first modem down by a predetermined reduction factor to obtain factored signals in addition to means for performing an inversion mapping comprising a scaling of the amplitude level of the factored, .mu.-law encoded signals up by a predetermined inversion factor to obtain a gain in the amplitude level of the factored signals corresponding to the predetermined loss inserted in the amplitude levels of the transmitted .mu.-law encoded signals. In accordance with an alternate embodiment, the minimization of quantization noise is effected independently of the transmitting modem through an inversion map…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.