As we indicated at the beginning of this second, a signal
can be transmitted from one point of space to another by means of
a displacement of the maximum, since this maximum is distinguished
from other maxima.
A disturbance of this kind concentrated in space is called a 
wave packet.
Image
The propagation of a signal of arbitrary shape
a wave packet needs not necessarily have the form shown in the
figure above.
By choosing a relationship for focus other than that in the
equation, the shape of get can be changed.


