aural null

aural null

[′ȯr·əl ′nəl]
(navigation)
A signal generated by the operator of a direction finder by the back-and-forth rotation of a loop antenna or the goniometer of an Adcock or other directional antenna system; the position of the rotating mechanism at which the null (minimum signal) is determined to be located indicates the azimuth or bearing of the radio station from which the emission is known to have originated.