US 7,321,639 B2
Demodulator and address information extractor
Akira Yamamoto, Takatsuki (Japan)
Assigned to Matsushita Electric Industrial Co., Ltd., Osaka (Japan)
Appl. No. 10/513,149
PCT Filed Jan. 26, 2004, PCT No. PCT/JP2004/000635
§ 371(c)(1), (2), (4) Date Nov. 02, 2004,
PCT Pub. No. WO2004/079738, PCT Pub. Date Sep. 16, 2004.
Claims priority of application No. 2003-061429 (JP), filed on Mar. 07, 2003.
Prior Publication US 2005/0169404 A1, Aug. 04, 2005
Int. Cl. H03D 3/22 (2006.01)
U.S. Cl. 375—329  [369/44.13; 375/316] 12 Claims
OG exemplary drawing
 
1. A demodulator comprising:
carrier information extraction means for extracting carrier information from a BPSK modulated signal;
carrier generation means for generating a carrier based on the carrier information extracted by the carrier information extraction means;
analog-to-digital conversion means for converting the BPSK modulated signal to a digital value;
multiplication means for multiplying the carrier output from the carrier generation means by the BPSK modulated signal digitized by the analog-to-digital conversion means;
carrier period integration means for integrating a result of the multiplication performed by the multiplication means, with respect to a period of the carrier generated by the carrier generation means; and
discrimination means for binarizing a result of the integration performed by the carrier period integration means,
wherein at least one of the carrier information extraction means and the carrier generation means is composed of a digital circuit, and
the carrier generation means generates, as the carrier, a modified square wave, in which if the amplitude of the modified square wave is 1 during the period of time in which the phase thereof is from 0 to π/3, the amplitude becomes 2 during the period of time in which the phase is from π/3 to 2π/3, the amplitude becomes 1 during the period of time in which the phase is from 2π/3 to π, the amplitude becomes −1 during the period of time in which the phase is from π to 4π/3, the amplitude becomes −2 during the period of time in which the phase is from 4π/3 to 5π/3, and the amplitude becomes −1 during the period of time in which the phase is from 5π/3 to 2π.