Symbol sign directed phase detector
US6430243B1 · kind B1 · utility
Assignees
Inventor
Key dates
| Filing date | Aug 31, 1998 |
| Grant date | Aug 6, 2002 |
| Priority date | — |
| Expiry date | Aug 31, 2018 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N11/24
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A phase detector that uses symbol sign information to aid the phase error detection process to determine a phase error of a complex signal such as a vestigial side band (VSB) signal. The phase detector comprises a subtractor having one input coupled to the I signal (i.e., an unquantized digital value that is sometimes referred to as a quasi-analog signal) and a second input coupled to the data output of a slicer (quantizer) representing the magnitude of a sample point within a symbol (i.e., a digital value representing one of M levels of the VSB signal). The unquantized signal is subtracted from the quantized I signal to produce a &Dgr;I signal. The I signal is also processed to determine the sign of the present symbol. A before-after symbol processor determines the sign values of a previous (before) symbol and a later (after) symbol and compares those signs to the sign of the present symbol. A change in signs from the before symbol to the after symbol will produce a substantial imaginary component in the phase error signal that can easily be tracked by the phase tracking loop. If the signs of the symbols (before-to-after) do not change, then the imaginary component of the phase er…
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