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COMPENSATION FOR SECOND ORDER INTERMODULATION IN A HOMODYNE RECEIVER
COMPENSATION FOR SECOND ORDER INTERMODULATION IN A HOMODYNE RECEIVER
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机译：均方接收机中二阶互调的补偿
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摘要
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.
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