Complex sentence: Both systems consist of a heated silicon carbide block that radiates a large amount of infra-red energy, it is surrounded by a large cylindrical mechanical shutter, that modulates the infra-red output, producing a pulsing pattern.
Split into simpler sentences: Both systems consist of a heated silicon carbide block that radiates a large amount of infra-red energy. It is surrounded by a large cylindrical mechanical shutter that modulates the infra-red output, producing a pulsing pattern.