Modulator demodulator for binary digitally encoded messages
US3980824A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Oct 29, 1974 |
| Grant date | Sep 14, 1976 |
| Priority date | — |
| Expiry date | Oct 29, 1994 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04L25/4904
- WIPO fieldDigital communication
- WIPO sectorElectrical engineering
Abstract
In a communications system utilizing binary messages, a modulator for differentially modulating the messages, i.e. a change in the differentially encoded data is produced for every "one" in the data stream and no change occurs for every "zero" in the data stream, the differentially encoded data is modulated by a square wave signal having a predetermined number of cycles per bit of information, and the output is passed through a band pass filter to remove a substantial portion of the upper side band, and the DC. In the demodulator the modulated, differentially encoded message is applied to one input of an exclusive OR and the same message is delayed one bit and applied to a second input of the exclusive OR to remove the modulation and differential encoding, after which the message is integrated and shaped to place the message in the original binary form.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.