Method of, and demodulator for, digitally demodulating an SSB signal
US4803700A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jun 10, 1986 |
| Grant date | Feb 7, 1989 |
| Priority date | — |
| Expiry date | Jun 10, 2006 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03D1/24
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
An SSB signal demodulator comprising an analog bandpass filter for band-limiting such signal, an analog-to-digital converter 20 for digitizing the band-limited signal, and a pair of quadrature related decimating filters (28, 29) for deriving quadrature related decimated signals therefrom which are applied to a Hilbert transform pair (30, 31). The upper or lower sideband signal is obtained by taking the sum or difference of the outputs of the Hilbert transform pair, and the resulting digital signal is reconverted to an analog signal. By using a decimation factor which is an odd numbered integer greater than 1, the periodic transfer function of the demodulator has alternate passbands and stopbands. This relaxes the performance requirements of the analog filter and of the Hilbert transform pair, and greatly enhances the adjacent channel selectivity of the demodulator.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.