Process for the demodulation of an amplitude modulated signal and demodulator performing this process
US4412181A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Mar 27, 1981 |
| Grant date | Oct 25, 1983 |
| Priority date | — |
| Expiry date | Mar 27, 2001 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N11/165
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A process for the demodulation of an amplitude modulated signal composed of two suppressed carriers, at a same frequency F and in phase quadrature, which are respectively modulated by two modulation signals, the modulated signal being preceded by a reference signal at frequency F, by PA1 sampling the reference signal and the modulated signal, according to a frequency m.F (m being an integer); PA1 determining a polar angle .psi..sub.t of a rotating vector representing the reference signal, at time t, by calculating: ##EQU1## where x(t) and x(t-(1/4F)) are the values of two successive samples of the reference signal; PA1 determining polar coordinates (.rho..sub.t, .theta..sub.t) of a rotating vector representing the modulated signal, at time t, by calculating: ##EQU2## where y(t) and y(t-(1/4F)) are values of two successive samples of the modulated signal, PA1 calculating .gamma.=.theta..sub.t -.omega..sub.t -.phi..sub.o, where .phi..sub.o is the phase displacement between the reference signal and one of the carriers, PA1 calculating .alpha.=.rho..sub.t.cos .gamma. EQU .beta.=.rho..sub.t.sin .gamma. and PA1 generating two signals whose instantaneous amplitudes are .alpha. and .lambda…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.