It is well known that a pulsed signal emitted some distance from the earth will undergo dispersion due to the plasma (ionized hydrogen) between stars in our galaxy. Short (<100 ms) pulsed signals are presently a topic of great interest for many astronomers; SETI scientists imagine ET may signal in this way, millisecond pulsar observations suffer this dispersion, and everyone is interested in astronomical bodies that might emit short pulse radiation as from a collapsing black hole.
Meanwhile, the square kilometer array study group is thinking how they might build a pulse detector. Here is a memo describing the work:
Not long ago I posted a memo which gives an introduction that may be helpful: