Partial response QAM modem
US4123710A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Nov 30, 1977 |
| Grant date | Oct 31, 1978 |
| Priority date | — |
| Expiry date | Nov 30, 1997 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04L27/362
- WIPO fieldDigital communication
- WIPO sectorElectrical engineering
Abstract
A partial response QAM Modem is provided wherein a transmit signal is generated by modulating band limited, multilevel, partial response precoded data with inphase and quadrature carriers in inphase and quadrature phase channels, respectively, and summing the modulated outputs. The received signal is processed by a passband automatic complex equalizer. The equalized signal is delayed and then demodulated with recovered inphase and quadrature carriers to recover the inphase and quadrature phase baseband signals. The recovered baseband signals are sampled at appropriate instants to produce estimates of the transmitted symbols. These symbols are partial response decoded and processed by error correctors to improve the overall system performance. The error corrector outputs are decoded to convert the multilevel estimated data to binary data and the binary data of the two channels is summed to obtain estimates of the binary data transmitted.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.