Multiplexed data modem
US3943285A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | May 10, 1973 |
| Grant date | Mar 9, 1976 |
| Priority date | — |
| Expiry date | May 10, 1993 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04L27/2338
- WIPO fieldDigital communication
- WIPO sectorElectrical engineering
Abstract
A data modem that operates to permit the concurrent high speed transmission/reception of digital data over two independent data links or systems, is disclosed. Data bits concurrently applied to a transmitting modem from two independent data sources are interlaced to form a stream of data bits that are effectively grouped as data words to be differentially phase modulated. Modulated data may be transmitted over ordinary voice grade telephone lines to a distant receiver modem at effectively twice the bit rate of the individual data sources. Successive groups of six interlaced data bits are divided into two groups of three bits which are uniquely identified by having a selected phase angle added to or subtracted from the differential phase angle for alternate groups of three bits. The selectively added phase angle is detected at a receiving modem to identify the respective groups of three bits and thereby permit accurate distribution of demodulated data bits to the respective data utilization terminals corresponding to the two data sources.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.