A null detected by listening for the minimum or the absence of an audible signal
Related Terms |
HARMONIC
1. A sinusoidal quantity having a frequency that is an integral multiple of the frequency of a periodic quantity to which it is related. 2. A signal having a frequency which is an integral multiple of the fundamental frequency.
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HOP
Travel of a radio wave to the ionosphere and back to earth. The number of hops a radio signal has experienced is usually designated by the expression one-hop, two-hop, multihop, etc
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HEAT LIGHTNING
A flash of light from an electric discharge, without thunder, believed to be the reflection by haze or clouds of a distant lash of lightning, too far away for the thunder to be audible
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HOMING
Navigation toward a point by following a signal from that point. Radiobeacons are commonly used for homing.
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INFRASONIC
Having a frequency below the audible range. Frequencies above the audible range are called ULTRASONIC.
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INTERNATIONAL CALL SIGN
An alpha-numeric symbol assigned in accordance with the provisions of the International Telecommunications Union to identify a radio station. The nationality or the radio station is identified by the first three characters; also referred to as call letters or signal letters.
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BEAT TO QUARTERS
Prepare for battle (beat = beat the drum to signal the need for battle preparation)
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INTERROGATING SIGNAL
The signal emitted by interrogator to trigger a transponder
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INOPERATIVE
Said of a sound signal or radionavigation aid out of service due to a malfunction
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FLAG HOIST
A number of signal flags strung together to convey a message.
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