heterodyne detector(het -ĕ-rŏ-dÿn) A system that analyzes the frequency spectrum of a signal at very high spectral resolution. Originally developed in the radio-frequency region, systems are now being built to allow far-infrared and submillimeter studies of astronomical objects. Basically, the radiation collected by a telescope is converted to a signal of lower frequency that can then be handled electronically. This is achieved by heterodyning, or merging, the signal with one from a local oscillator (see receiver). Once at the lower frequency the signal is much easier to process. It is analyzed in a spectrometer that further converts the signal from the time domain to the frequency domain and can in principle be analyzed at any resolution. The entire spectrum within the bandwidth is processed in parallel.
heterodyne detector[′hed·ə·rə‚dīn di′tek·tər]
A detector in which an unmodulated carrier frequency is combined with the signal of a local oscillator having a slightly different frequency, to provide an audio-frequency beat signal that can be heard with a loudspeaker or headphones; used chiefly for code reception.