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March 5, 2009
This is a picture of the Heterodyne Instrument for the Far Infrared's (HIFI) focal plane unit.

HIFI is a very high-resolution heterodyne spectrometer. The heterodyne detection principle involves translating the frequency range of the signal observed by the telescope to a lower frequency where it is easier to perform the required measurements.

This is done by mixing the incoming signal with a very stable monochromatic signal, generated by a local oscillator, and extracting the difference frequency for further processing. HIFI observes in seven bands covering 480 to 1910 gigaHertz.

The scientific observations from HIFI will among other objectives help astronomers understand the interrelation between stars and the interstellar medium.

It was developed by a consortium led by SRON Netherlands Institute for Space Science.

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