Multimode digital modem
US6055268A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jun 20, 1996 |
| Grant date | Apr 25, 2000 |
| Priority date | — |
| Expiry date | Jun 20, 2016 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY02D30/50
- WIPO fieldDigital communication
- WIPO sectorElectrical engineering
Abstract
A modem communication system with receiving and transmission paths includes a direct equalizer system having an adaptive filter (1532) in the transmission path to compensate for frequency distortion of the communication channel. The transmitter filter coefficients are adapted by a filter coefficient calculator (1528), under control of a data detector (1526) which detects incoming data in the receiving path. A switch (1534) is controlled by status of a transmit output data buffer to multiplex either the training sequence or output data into the transmission path. When the buffer is idle, the training sequence generator (1540) is linked to a digital-to-analog (D/A) converter (1536) and line driver (1538). The receiving path includes an isolation switch (1520), a receiver amplifier (1522) and a slicer (1524). The receiver correlates the received training sequence with a known training sequence and updates the equalizer filter coefficients using an adaptation algorithm, such as a least mean squared algorithm. A first embodiment utilizes a high speed digital programmable filter (1532). Another embodiment utilizes a data buffer (1533) which is periodically filled with data filtered by a …
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.