bit reversed order

[jazziebrain]

Hello All!
I am fairly new to vhdl and I was wondering if anyone can help me
understand a few things about the Inverse fast fourier transform.
There is tons of information on the web but am still very confused.
Please excuse my slow learning.

Here is my scenerio:
I have two bit streams of I and Q samples (8 bits eachI have to
1.put in bit reversed order - I believe I have this down but I do not
understand how they relate to coordinates on a graph (for example
QPSK). How do you go from converting the I and Q samples from bit
reversed order to a graph.

I then must take the IFFT with the data from thathas been bit
reversed.Does this mean I take the coordinate values that are
represented by the scrambled data of the scrambled data?

Please bare with me. I have been researching this for quite some time
and still do not understand.

One last question, I am familiar with the IFFT equation but do not
understand how you represent the exponential value in vhdl?

Thanks in Advance for all your help.

 

[jazziebrain]

Never mind I figured it out. For those with the same question:

bit reversal just means you reverse the order,i.e., "001" change to
"100", "110" to "011",..etc.

and as for the exponential just use this simple equation:

e^(-2*pi*i*k/N) = cos(-2*pi*i*k/N)+jsin(-2*pi*i*k/N)

where N is N-point transform
k is sample #
just use trig basic functions to figure out the coordinates on the
unit circle.

I hope this helps others!