set term postscript eps enh "Times-BoldItalic"
set size 0.5,0.5
set xzeroaxis lt -1
set xrange [0:2000]
set yrange [0:1]
set xlabel "Frequency"  0,0.5 font "Helvetica,16"
set ylabel "Amplitude" 0.45,0 font "Helvetica,16" 
set xtics  0, 1000, 2000
set mxtics 10
set ytics -1,1.0,1   
set key off    
#set title "graph-2" font "Helvetica,16"
set bmargin 3
set lmargin 6
set rmargin 2
set tmargin 2
set output "plotoutput.ps" 
plot "spectrum.dat" with lines linewidth 1