IFFT on padded vector with zeros

2013 2 21
2 个回答
4 次查看（30 天）

0 个投票

hello,
I have a vector that padded with zeros and I want to perform IFFT on this vector, as follows: [ 1 2 3 4 0 0 0 . . . 0 0 4 3 2 1] In that case, do I need to multiply IFFT with scaling factor?
Thanks,

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回答（2 个）

Matt J
Matt J 2013-2-21
编辑：Matt J 2013-2-21

0 个投票

You might have to scale by a length-dependent factor, depending on what it is you're trying to preserve. For example, if you want to satisfy Parseval's theorem, you have to scale by sqrt(length(x)),
>> x1=[ 1 2 3 4 4 3 2 1];
>> x2=[ 1 2 3 4 0 0 0 0 4 3 2 1];
>>
>> y1=ifft(x1)*sqrt(length(x1));
>> y2=ifft(x2)*sqrt(length(x2));
>> [norm(x1), norm(y1)] %Parseval satisfied
ans =
7.7460 7.7460
>> [norm(x2), norm(y2)] %Parseval satisfied
ans =
7.7460 7.7460
Michael Adelman
Michael Adelman 2013-2-22

0 个投票

I want to pad this vector with zeros before IFFT for OFDM transmission. In that case what scaling factor should be?

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