# Meaning of output value?

Discussion in 'VHDL' started by Sander Odekerken, May 18, 2004.

1. ### Sander OdekerkenGuest

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?

thanks,

Sander Odekerken

Sander Odekerken, May 18, 2004

2. ### SymonGuest

Symon, May 18, 2004

3. ### John_HGuest

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!

"Sander Odekerken" <> wrote in message
news:c8ddio\$drv\$1.nb.home.nl...
> 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?
>
>
> thanks,
>
> Sander Odekerken
>
>

John_H, May 18, 2004