| US 7,469,022 B2 | ||
| Methods and apparatus for symmetrical phase-shift keying | ||
| Chin Lee, Xindian (Taiwan) | ||
| Assigned to Via Technologies, Inc., Taipei (Taiwan) | ||
| Filed on Nov. 23, 2004, as Appl. No. 10/996,676. | ||
| Prior Publication US 2006/0109933 A1, May 25, 2006 | ||
| Int. Cl. H04L 27/20 (2006.01) | ||
| U.S. Cl. 375—308 [375/329; 375/332; 375/302; 375/330; 375/324; 375/331; 375/316; 329/308; 329/304] | 22 Claims |
| 1. A symmetrical phase-shift keying (SPSK) method for data modulation, wherein each symbol in a transmission signal carries
n-bit information and is transmitted with one of 2n+1 directions, 2n directions among the 2n+1 directions regarded as default directions and the other 2n directions regarded as complementary directions, each default direction having a corresponding complementary direction with
a phase difference of π and representing the same n-bit information as the default direction, the SPSK method comprising:
retrieving one of the default direction corresponding to a current symbol of the transmission signal;
determining whether a phase difference between the retrieved default direction and a previous direction of a previous symbol
in the transmission signal is less than or equal to π/2;
transmitting the current symbol according to the retrieved default direction if the phase difference is less than or equal
to π/2; and
transmitting the current symbol according to a complementary direction that corresponds to the retrieved default direction
if the phase difference exceeds π/2.
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