Describe with suitable example; frequency measurement by Lissajous patterns on CRO.

Describe with suitable example; frequency measurement by Lissajous patterns on CRO. 
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Answer :

* Initially the unknown frequency signal is connected to vertical deflection plates of CRO. * Now switch of the internal sweep generator of the horizontal deflecting system. * A standard source of frequency is applied to the horizontal deflection plates. * The frequency of standard source is adjusted now until a circular or elliptical pattern appears on CRT screen. * When such pattern is observed on a screen, it indicates that two frequencies are equal. * Practically, it is not possible to adjust the standard frequency exactly equal to unknown frequency. Hence the standard frequency is adjusted to be a multiple or submultiple of unknown frequency.

Vertical input Frequency measurement by Lissajous patterns on CRO can be explain by following example: Assume horizontal input frequency is 10 kHz for following pattern

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