Whistling Meteor

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Whistling Meteor

</dt>
Name applied to a radio meteor when a detection system is used in which the presence of the meteor is indicated by a rapidly changing audiofrequency radio signal. </dd>
The maximum reflection of a radio signal from a radio meteor occurs when the ion column is perpendicular to the line from the column to the transmitter-receiver. During the approach of the meteor to this position, the Doppler effect causes a change in the frequency of the reflected signal. When the reflected signal frequency is then combined with the transmitter frequency, the difference between the transmitted and reflected frequencies produces an audiofrequency beat. The audiofrequency beat, when amplified and fed to a loudspeaker, allows the meteors to be heard as a high-pitched whistle which rapidly falls to zero frequency as the meteor trail becomes normal to the line of sight. [[/a>|/a> ]]

References

This article is based on NASA's Dictionary of Technical Terms for Aerospace Use