Method and apparatus for transmitting data over limited bandwidth channels
US4403331A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | May 1, 1981 |
| Grant date | Sep 6, 1983 |
| Priority date | — |
| Expiry date | May 1, 2001 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04L27/3411
- WIPO fieldDigital communication
- WIPO sectorElectrical engineering
Abstract
A method of developing waveforms having the energy therein concentrated within a limited bandwidth and modems for generating, transmitting, and receiving digital data utilizing such waveforms as carriers. A set of mutually orthogonal basis signals are selected to maximize their energies within the channel, each is binary coded and stored in the modem. A set of optimized coefficients is stored and utilized to weight each basis function in a coding arrangement to define bytes of digital data. The coded and weighted basis functions for each successive byte are summed to form a composite signal and transmitted over the channel as an analog waveform. Stored basis signals at the receiving end are correlated with the received waveform to thereby extract the coefficients which are decoded to reproduce the transmitted bytes. Both coding gain and reduction of intersymbol interference is achieved.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.