Modulation and demodulation of plural channels using analog and digital components
US5444415A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Mar 1, 1994 |
| Grant date | Aug 22, 1995 |
| Priority date | — |
| Expiry date | Mar 1, 2014 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04L2027/0057
- WIPO fieldDigital communication
- WIPO sectorElectrical engineering
Abstract
In the modulation and demodulation of a plurality of frequency separated channels on a radio frequency carrier by digitally coded speech or data, the speech or data is modulated on a digitally generated sub-carrier by quadrature phase shift keying and after conversion to analogue form the modulated sub-carrier is mixed with an RF carrier of fixed frequency to produce the signal for transmission. Reception and demodulation of the transmitted signal are effected by the reverse processes. Frequency multiplication is effected after the digital to analogue conversion by producing analogue samples of very short duration and applying them to a suitable filter. Frequency division during the analogue to digital conversion is effected by sub-sampling.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.