Digital demodulator
US6639951B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | May 18, 2000 |
| Grant date | Oct 28, 2003 |
| Priority date | — |
| Expiry date | May 18, 2020 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04L2027/0095
- WIPO fieldDigital communication
- WIPO sectorElectrical engineering
Abstract
A digital demodulator that eliminates the need for an absolute phase circuit is provided. In a digital demodulator for a digital broadcasting receiver that receives digital time-division multiplexed signals of different types of modulation, the demodulated baseband signal is selectively inverted by an inverter (7) according to an inversion command signal “0” or “1” that is output from an inversion decision circuit (6) depending on a BPSK signal of a known pattern. A phase error detector (8) for carrier reproduction determines the phase error voltage based on the phase difference between the absolute phase and the phase of the signal point of the demodulated baseband signal output from the inverter (7). The phase error voltage is passed through a carrier filter (9), including a low-pass filter, to control the carrier frequency so that carrier reproduction can be carried out with the phase at the signal point being coincident with the point of phase convergence.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.