unset xtics
set ytics ("" -1 1, "" 0, "" 1 1)
set xtics 10
unset border
set grid xtics ytics   # and make a grid of them
set format x ""
set format y ""
set key off

set xrange [-5:115]
set samples 12000

set terminal png size 1024,100 enhanced

set output "carrier.png"
plot sin(x*pi) with lines

set output "cw.png"
#   0-30 40-50 60-90 100-110
plot sin(x*pi)*((x>0 && x<30)||(x>40 && x<50)||(x>60 && x<90)||(x>100 && x<110)) with lines

set output "psk-bad.png"
#   0-30 40-50 60-90 100-110
plot sin(x*pi)*(-1+2*((x>0 && x<30)||(x>40 && x<50)||(x>60 && x<90)||(x>100 && x<110))) with lines

set output "psk-good.png"
#   0-30 40-50 60-90 100-110
dits(x)=cos((x-5)*pi/10)
plot sin(x*pi)*( \
     dits(x)*(x< 5) \
   +       1*(x> 5 && x<25) \
   + dits(x)*(x>25 && x<65) \
   +       1*(x>65 && x<85) \
   + dits(x)*(x>85)) with lines