Modulator utilizing high and low frequency carriers
US4481490A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jun 7, 1982 |
| Grant date | Nov 6, 1984 |
| Priority date | — |
| Expiry date | Jun 7, 2002 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03D7/14
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
To minimize carrier leak in the modulation of voice frequencies to the desired line frequency for a carrier system, a first balanced modulator is operated at a low frequency where low carrier-leak modulators may be constructed and a second balanced modulator, directly coupled to the first, is employed. The modulation frequency of said second modulator is very high compared to that of said low-frequency modulator. The sideband obtained from the second modulation stage is remote from said high-frequency carrier and a band-pass filter selects the desired sideband and substantially eliminates the high-frequency carrier and the other sideband. Thus, only a low amplitude of carrier leak is present which may cause interference with other channels.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.