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Altera_Forum
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11 years ago

Inphase (I) and Quadrature (Q) components of signals

Hi All, How to calculate the Inphase (I) and Quadrature (Q) components of signals, such as RF signals? I would like to shift the RF signals to a specific baseband frequency and then derive the ...
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Altera_Forum
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11 years ago

Hi Lee,

I/Q demodulation is simply a direct implementation of the Fourier frequency shift theorem, i.e., multiplication by a complex-valued exponential in the time-domain results in a frequency shift in the frequency-domain. The complex-valued exponential can be split into cos + j*sin (Euler's rule), and that is what you implement in hardware.

Take a look at these FPGA-DSP notes for more details ...

http://www.ovro.caltech.edu/~dwh/correlator/pdf/esc-104paper_hawkins.pdf

Cheers,

Dave