heterodyne frequency meter

heterodyne frequency meter

[′hed·ə·rə‚dīn ′frē·kwən·sē ‚mēd·ər]
(electronics)
A frequency meter in which a known frequency, which may be adjustable or fixed, is heterodyned with an unknown frequency to produce a zero beat or an audio-frequency signal whose value is measured by other means. Also known as heterodyne wavemeter.