% calculate intermodulation products
 clear
 f0=120e6;
 B=3e6;
 flo=f0-B/2; fhi=f0+B/2;
 ftgt=1400;
 fclt=20500;
 f1=f0+ftgt;
 f2=f0+fclt;
  it=0;
  for m=-3:3
	  for n=-3:3
		  fmn=m*f1+n*f2;
 	  if fmn<=fhi & fmn>=flo, it=it+1; ff(it)=fmn; end
	  if fmn>=-fhi & fmn<=-flo, it=it+1; ff(it)=fmn; end
	  end
  end
  
