Telecommunications – Receiver or analog modulated signal frequency converter – Frequency modifying or conversion
Patent
1996-07-18
1998-05-05
Au, Amelia
Telecommunications
Receiver or analog modulated signal frequency converter
Frequency modifying or conversion
455317, H04B 126
Patent
active
057490511
ABSTRACT:
A homodyne radio receiving apparatus is provided for mitigating fixed or variable DC offsets produced by residual second order intermodulation terms due to unwanted signals. The homodyne radio receiving apparatus includes an antenna, an antenna by-pass filter, an RF amplifier and a quadrature downconverter. The quadrature downconverter for the complex base band is centered around a desired reception frequency so that the complex baseband signals lie around zero frequency. A supplementary total power detector is provided to measure the total received power through the antenna by-pass filter so that the unwanted terms caused by second order intermodulation are compensated. The compensation is achieved by feeding instantaneous power measurements to a signal processing unit along with the complex baseband signals. The signal processing unit then determines a complex compensation coefficient by correlating the power signal with the complex baseband signals. The complex compensation coefficient is then employed to subtract a weighted amount of the power signal from the complex baseband signals in order to cancel the unwanted second order intermodulation distortion terms.
REFERENCES:
patent: 5241702 (1993-08-01), Dent
patent: 5530929 (1996-06-01), Lindqvist et al.
patent: 5614904 (1997-03-01), Dent
Au Amelia
Ericsson Inc.
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