Telecommunications – Receiver or analog modulated signal frequency converter – Frequency modifying or conversion
Patent
1997-07-18
2000-02-22
Hudspeth, David R.
Telecommunications
Receiver or analog modulated signal frequency converter
Frequency modifying or conversion
455339, 455 69, 455 70, 455131, H04J 1300
Patent
active
060290587
ABSTRACT:
A method and apparatus for passband communication using direct conversion avoids 1/f and DC-offset noises by shaping the spectrum of the signal so that it has little energy near zero frequency. After the receiver frequency down-converts the signal to baseband, it filters frequencies in the neighborhood of zero prior to demodulation. Since the spectrum of the signal was shaped by a coder prior to transmission so that it has little energy content near zero frequency, the filtering at the receiver eliminates 1/f and DC-offset noise without reducing significantly the energy of the desired information signal. After the noise has been filtered, the receiver demodulates and decodes the signal to recover the information signal. The coding can be based upon broadening of the amplitude range or the frequency range to create the required spectrum shaping.
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Meng Teresa H. Y.
Namgoong Won
Abebe Daniel
Hudspeth David R.
The Board of Trustee of the Leland Stanford Junior University
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