Decoding device for performing amplitude-phase demodulation and viterbi decoding
US5568517A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | May 4, 1995 |
| Grant date | Oct 22, 1996 |
| Priority date | — |
| Expiry date | May 4, 2015 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04L27/38
- WIPO fieldDigital communication
- WIPO sectorElectrical engineering
Abstract
A modulator-demodulator (i.e., modem) permits a personal computer and the like to receive and transmit data in digital format across voice-oriented communications links such as telephone lines. A full-duplex-type modem employs a decoding device decoding the data which are subjected to convolution-encoding operation and amplitude-phase modulation. That data is subjected to amplitude-phase demodulation at first: and then, it is subjected to viterbi decoding by which an error correction is carried out. In the amplitude-phase demodulation, an amplitude-phase plane is employed and is divided into a plurality of areas in accordance with an arrangement of signal-placing points which is used by the amplitude-phase modulation. When receiving the data, a certain receiving point is defined. Then, one of the areas to which the receiving point belongs is determined; and its area information is produced. A plurality of candidate paths are determined by referring to the signal-placing points which are arranged around the area to which the receiving point belongs. A distance between the receiving point and each signal-placing point is computed with respect to each of the candidate paths, thus even…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.