The (normalised) transmission pattern of what was an ASCII '[' (binary 01011101) using rectangular bipolar non-return-to-zero signalling that has been sent through a bandlimited channel. This channel has filtered the rectangular pulse shape to an approximate sinc function resulting in an error in the received message, which is 01011111 (an ASCII '_'). The output decision is modelled as a simple integrate-and-dump circuit followed by a sampler synchronised to the bit periods; the resulting output is overlaid in blue.
Intended for use as one of a series of example images in the en:Intersymbol interference article on en. The other images include:

Image:ISI Initial Bipolar NRZ Signal.svg - The initial (rectangular) message
Image:ISI Bandlimited Pulse Shape.svg - The pulse shape resulting from the bandlimited channel
Image:ISI Multipath Corrupted Bipolar NRZ Signal.svg - The same message corrupted by multipath effects
Made using MATLAB, converted to SVG with this script, and final editing (adding the binary values along the top) done with a text editor. If you want the MATLAB code feel free to contact me.
Own work
Blair Bonnett