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Method to increase performance of secondary data in a hierarchical modulation scheme

  • US 7,230,998 B2
  • Filed: 05/18/2004
  • Issued: 06/12/2007
  • Est. Priority Date: 11/26/2003
  • Status: Active Grant
First Claim
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1. In a digital data transmission system including a transmitter for transmitting transmit signals, a receiver comprising:

  • a receiving unit including satellite signal detection means for detecting a first transmit signal transmitted from a first communication satellite and a second transmit signal transmitted from a second communication satellite, the first transmit signal produced when the transmitter modulates a primary data stream with a secondary data stream on a first carrier wave associated with the first communication satellite and the second transmit signal produced when the transmitter modulates the primary and secondary data streams on a second carrier wave associated with the second communication satellite, said receiving unit further including a terrestrial signal detection means for detecting a third transmit signal transmitted from a terrestrial repeater, the third transmit signal produced when the terrestrial repeater receives at least one of the first and the second transmit signals and modulates the primary data stream with the secondary data stream on a third carrier wave associated with the terrestrial repeater; and

    at least one demodulator coupled to said receiving unit and configured to demodulate at least one of the first and the second transmit signals,wherein the terrestrial signal detection means include an antenna in communication with a tuner unit for receiving the third transmit signal, wherein the third transmit signal is produced when the primary and the secondary data are re-encoded on the third carrier wave using an OFDM modulation scheme, the OFDM modulation scheme dividing the third carrier wave into multiple sub-carrier waves each having one of a M-PSK, D-MPSK and pi/4 D-MPSK modulation scheme.

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