In electronics, a super heterodyne receiver (often shortened to superhet) uses frequency mixing to convert a received signal to a fixed intermediate frequency (IF) which can be more conveniently processed than the original radio carrier frequency. It was invented by US engineer Edwin Armstrong in 1918 during World War I. Virtually all modern radio receivers use the super heterodyne principle. At the cost of an extra frequency converter stage, the super heterodyne receiver provides superior selectivity and sensitivity compared with simpler designs.