Digital signal processor modem
US4620294A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Sep 9, 1983 |
| Grant date | Oct 28, 1986 |
| Priority date | — |
| Expiry date | Sep 9, 2003 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04L1/0003
- WIPO fieldDigital communication
- WIPO sectorElectrical engineering
Abstract
A dual speed, full duplex modem for transmitting and receiving data on a dialed-access telephone line includes a signal processor for storing samples corresponding to a sinusoidal waveform, for selecting samples at intervals determined by the mode in which the modem is operating to synthesize a signal for modulating by data for transmission, and for autocorrelating a received signal at a frequency determined by the mode in which the modem is operating to recover data from the received signal. The signal processor includes configuring input ports, and a microcomputer receives instructions related to the mode in which the modem is to operate to output a mode-configuring word to the configuring inputs. Conversion from the signal processor's digital output to the analog signal to the line and from the line's analog signal to the signal processor's digital input take place through two time-division multiplexed coder-decoders. The stored sinusoid is mu-law compressed. The modem can dual tone, multiple frequency dial. The DTMF pair requires a different amplitude from the amplitude of the synthesized signal for modulating by data for transmission. A power series expansion of the required a…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.