Title: Modulation method and device for executing Nyquist folding frequency
Application Number: 02142817 Application Date: 2002.09.18
Publication Number: 1409525 Publication Date: 2003.04.09
Approval Pub. Date: Granted Pub. Date:
International Classifi-cation: H03C3/00;H04L27/12
Applicant(s) Name: Thomson Licensing Corp. Address:
Inventor(s) Name: D. L. Mcneily
Attorney & Agent: zou guangxin chen ji
Abstract:
    A method and apparatus for re-modulating an RF carrier modulated signal using a Nyquist folding frequency modulation technique. The method modulates a digitized RF carrier modulated signal with a digital sequence of {1, -1, 1, -1, . . . }, where the center frequency of the RF carrier modulated signal is at a first frequency and the sample rate of the modulating signal is at a second frequency. When the second frequency is four times the first frequency, the output of the digital modulation process is a spectrum-inverted copy of the source RF carrier modulated signal. For all other frequencies, the remodulated RF carrier modulated signal has a center frequency equal to the carrier frequency minus one-half the sample rate of the modulating signal. A spectrum inversion is then performed to recreate the spectrum of the source RF carrier modulated signal, which is now located at a different center frequency.
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