The Heterodyne Instrument for the Far Infrared (HIFI) is a very high-resolution heterodyne spectrometer. It works by mixing the incoming signal with a stable monochromatic signal, generated by a local oscillator, and extracting the frequency difference for further processing in a spectrometer. HIFI will have seven separate local oscillators covering two bands from 480-1250 GHz and 1410 1910 GHz. The instrument was developed by a consortium led by SRON Netherlands Institute for Space Research.