Meaning of output value?

May 18, 2004 2 Replies

Hello everybody,



For a school project I use the Xilinx Coregen FFT core. It does work, but what does the output mean? Is the Real output the amplitude and the Imaginary output the phase?



If anyone knows, please HELP!!!



thanks,



Sander Odekerken


This is an extremely basic question about complex math.

Real and Imaginary number pairs make up a cartesian coordinate pair. Think of the real part as the x-axis and the imaginary part as the y-axis.

Amplitude and phase values produce a polar coordinate location. Think of the amplitude as the distance from the (x,y)=(0,0) origin and the phase as the angle counter-clockwise from the x-axis.

The conversion from cartesian to polar comes from: amplitude^2 = x^2 + y^2 tan( phase ) = y/x

I hope your FPGA work doesn't get hampered too much by your limited engineering-math knowledge. Good luck with the project!

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