Bandpass spectral shaping of data signals
US5953374A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Mar 3, 1997 |
| Grant date | Sep 14, 1999 |
| Priority date | — |
| Expiry date | Mar 3, 2017 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04L25/4927
- WIPO fieldDigital communication
- WIPO sectorElectrical engineering
Abstract
A process for transmitting data selects sample values that represent data symbols and then converts the sample values to voltage levels in a transmitted PAM signal. A receiver samples the PAM signal and identifies the data symbols from the sampled voltage levels. At least some of the data symbols have multiple alternative representations; and for a data symbol having multiple alternatives, a sample value is selected to reduce low and high frequency components in the PAM signal. Accordingly, the PAM signal carries less information at low and high frequencies and is less disturbed by transformers, low pass filters, and local loop impairment in the transmission channel. The process for selecting sample values determines a weighted average of the lowest and highest frequency components. The weighting of the average can be selected according to a measured frequency response of the channel during initialization.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.