function Detect(cutoff, file)

if(nargin < 1)
    cutoff = int(size(A,1)/2);
end

f = 1; %0.995; 
in = 1:72; 
filter1000 = sin(1000*f*(in)*3.14159*2/1000);
filter316 = sin(316*f*(in)*3.14159*2/1000);
filter100 = sin(100*f*(in)*3.14159*2/1000);

for rowrange = 1:2
    cutoff1 = cutoff;
    cutoff2 = min(cutoff1+40000, size(A,1));
    if(rowrange == 1)
	    rows = [1:cutoff1]; 
    elseif(rowrange == 2)
	    rows = [cutoff1+1:cutoff2];
    end
	columns = [4:10];
	
	for i = columns
        b(:,i) = A(rows,i);
        b1000(:,i) = conv(b(:,i), filter1000); 
        b316(:,i) = conv(b(:,i), filter316); 
        b100(:,i) = conv(b(:,i), filter100); 
	end;
	
	figure; 
	col = length(columns);
	for(i = columns)
        subplot(3,col,i-columns(1)+1); plot(b1000(:,i), '.');
        subplot(3,col,i-columns(1)+1+col); plot(b316(:,i), '.');
        subplot(3,col,i-columns(1)+1+2*col); plot(b100(:,i), '.');
	end;
	
	clear b;
	clear b1000;
	clear b316;
	clear b100; 
end