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Digital demodulator

  • US 6,813,321 B1
  • Filed: 07/21/2000
  • Issued: 11/02/2004
  • Est. Priority Date: 01/30/1998
  • Status: Expired due to Term
First Claim
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1. A digital demodulator of a receiver for digital broadcasting which receives and transmits digital modulated waves created by time-base-multiplexing waves modulated by a plurality of modulation systems, comprising:

  • known-pattern signal generating means for generating in synchronism with known-pattern signals in received digital modulated waves the same known-pattern signal as a known-pattern BPSK signal in the received digital modulated waves;

    carrier-reproducing phase error detecting means, which comprises a phase error table having one reference phase as a convergence point between two reference phases of signal point positions of BPSK demodulation baseband signals, for sending out a phase error output based on a phase error between the phase obtained from the signal point position of the demodulation baseband signals and the phase convergence point; and

    a carrier-reproducing loop filter which is controlled for enablement based on the known-pattern signals outputted from the known-pattern signal generating means and smoothes the phase error outputs during an enabling period, wherein carrier reproduction is implemented by controlling the frequency of a reproduced carrier so that, based on the output of the carrier-reproducing loop filter, the phase of said signal point position coincides with the phase convergence point.

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