Can someone explain the procedure in FFT block? Does it perform the same

function as in Matlab? How can we relate this FFT block in gnuradio to

FFT function in matlab?

I have same question.

When I create in GRC a system to check as following:

Constant source(1)—> Vector to stream (1->64) ----> FFT(Reverse,64,

blackmanharris(64))—> throttle(32k) —> complex to mag^2 —> Number

sink ( or file sink and read back in octave)

The result I have is that : 242,38333770 and 63 values near to 0

But in Matlab, the result should be : 1 and 63 values is 0

Can anyone explain it for me?

Duc Toan N. wrote in post #1123456:

I have same question.

When I create in GRC a system to check as following:Constant source(1)—> Vector to stream (1->64) ----> FFT(Reverse,64,

blackmanharris(64))—> throttle(32k) —> complex to mag^2 —> Number

sink ( or file sink and read back in octave)The result I have is that : 242,38333770 and 63 values near to 0

But in Matlab, the result should be : 1 and 63 values is 0Can anyone explain it for me?

I read through the code inside the GNU Radio and the qa_fft.py which is

test file for fft operation, an I found that he FFT block is the same in

Matlab and IFFT is little bit different to Matlab as following:

FFT:

Data source --> gr.fft_vcc(FFT_size, True,[], False,1) —> Destination

is the same result in Matlab

IFFT:

Data souce --> gr.fft_vcc(FFT_size, False,[], False,1)—> Multiple

constant 1/32 —> the same result in Matlab

I hope it is useful.

Cheers,

Toan Nguyen