| 摘要 |
A METHOD AND APPARTUS (102) FOR RE-MODULATING AN RF CARRIER MODULATED SIGNAL USING A NYQUIST FOLDING FREQUENCY OF THE 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. 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 HE SAMPLE RATE OF THE MODULATING SIGNAL. A SPECTRUM INVERSION IS THEN PERFORMED TO RECREATE THE SPECTRUM OF THE SOURCE RF CARRIER MODULATED SIGNAL, WHIICH IS NOW LOCATED AT A DIFFERENT CENTER FREQUENCY. THE APPARATUS (102) COMPRISES A MODULATING SIGNAL SOURCE (112) AND A DIGITAL MODULATOR 108. A RESAMPLER 106 AND A SPECTRUM INVERTER 110 MAY BE USED AS NEEDED.(FIG 1)
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