function e = plotfft(in,sampleRate);
%
% This function computes the FFT of an input and plots it on a easy to read plot.  The function also
% provides hamming squared windowing on the input data to reduce spectral splatter at the edges of the 
% block of input data.
%
% Kreeger Research LLC
% Copyright (c) 2009
%
MIN_dB = -120;  % minimum of 120 db below 0dB;
win = hanning(length(in))';
%win = hamming(length(in))'; 
winsq = win.*win;
bb = in.*winsq;
c = fft(bb);

if nargin < 2
  sampleRate = 1.0;
end

l = floor(length(in)/2)+1;
idx = [[l+1:length(in)] [1:l]];
c = c(idx);
%normalize
d = 10*log10(c.*conj(c));
e = d - max(d);

% trim to MIN
x = find(e < MIN_dB);  %trim to MIN_db 
e(x) = MIN_dB;

if(mod(length(in),2)==0)
  t = (1:length(in))/length(in) - 0.5; % works for even input lengths
else
  t = linspace(-0.5,0.5,length(in));; % works for odd input lengths
end
plot(t*sampleRate,e);
grid on;
xlabel('fs');
ylabel('dB');

title(['Normalized Frequency Plot (peak= ' int2str(max(d)) 'dB)'])