Making a wave packet

Inspired by this webpage http://hyperphysics.phy-astr.gsu.edu/hbase/Waves/wpack.html I set out to make my own wave packet. If you scroll down to the section called Wave Packets from Discrete Waves you'll see an illustration of putting together sinusoidal waves of slightly differing frequency. A single sine wave has constant amplitude everywhere - the wave is not localised. The superposition of slightly differing frequencies concentrates it with a peak in one place. I made a spreadsheet of sinwt + sin1.1wt + sin1.2wt + ... +sin1.8wt and here's what I got:

It would have looked more like theirs if I'd gone negative on the x-axis but it's not bad at showing localisation.