Shifting the Sinc filter in the frequency domain

Started by runinrainy February 1, 2018
Hello,

The following example from dsprelated.com shows the design of Sinc filter
with the following parameters.

The link of the example as below;
https://www.dsprelated.com/freebooks/sasp/Example_1_Low_Pass_Filtering.html

With the Matlab command fftshift the frequency response of the filter is
centered at 0 frequency which is 256 the frequency bin.

My question is, how can I move the center of this filter from the
frequency bin 256 to the frequency bin 150?

% Signal parameters:
f = [ 440 880 1000 2000 ];      % frequencies
M = 256;                        % signal length
Fs = 5000;                      % sampling rate

 Filter parameters:
L = 257;    % filter length
fc = 600;   % cutoff frequency

% Design the filter using the window method:
hsupp = (-(L-1)/2:(L-1)/2);
hideal = (2*fc/Fs)*sinc(2*fc*hsupp/Fs);
h = hamming(L)' .* hideal; % h is our filter

% Choose the next power of 2 greater than L+M-1
Nfft = 2^(ceil(log2(L+M-1))); % or 2^nextpow2(L+M-1)


plot(abs(fftshift(fft(h,512))))

Thanks in advance!
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Posted through http://www.DSPRelated.com
On 02/01/2018 09:24 AM, runinrainy wrote:
> Hello, > > The following example from dsprelated.com shows the design of Sinc filter > with the following parameters. > > The link of the example as below; > https://www.dsprelated.com/freebooks/sasp/Example_1_Low_Pass_Filtering.html > > With the Matlab command fftshift the frequency response of the filter is > centered at 0 frequency which is 256 the frequency bin. > > My question is, how can I move the center of this filter from the > frequency bin 256 to the frequency bin 150? >
Translation in the frequency domain is multiplication by a sine wave (for real, symmetric around DC translation) or by a complex exponential (for complex, look Ma I've got twice as wide a datapath translation). -- Rob Gaddi, Highland Technology -- www.highlandtechnology.com Email address domain is currently out of order. See above to fix.