Intermittent stream
An intermittent stream is a stream of spaceships which is based on a periodic stream, but which can contain holes where some of the spaceships are not present. There is a base period for the intermittent stream such that if a spaceship arrives at a specific location, then it always does so at a generation which is a multiple of the base period. For example, the output from a period 30 glider gun where every third glider is deleted is an intermittent stream. A pseudo-random glider generator can produce a complicated intermittent stream with no obvious pattern.
Intermittent streams can be used to transmit signals, where holes in the stream can also convey information. For example, the stream can be processed by an inverter having the same period.