Use of cro for frequency measurement, Electrical Engineering

Q. Explain the use of CRO for frequency measurement.

 

Measurement of frequency: The frequency of the periodic signals is easily measured with a CRO. The frequency of a signal to be measured is compared with a known frequency. A sinusoidal voltage of unknown frequency (the frequency which is to be measured) is applied to the vertical plates. If the ratio of two frequencies (f and f) is an integer, a clearly defined and distinctive pattern appears on the screen. These patterns are known as Lissajous pattern.

Let us assume that two sinusoidal voltages applied to the vertical and horizontal plates of the CRO have equal frequency and same phase and let that voltages applied to the plates be given as voltage at vertical plate.

When the frequency of the two voltages is not equal then to obtain the Lissajous pattern is not simple. Lissajous pattern may be classified into two general categories, the closed and the open Lissajous patterns. A closed Lissajous pattern is continuous and has no break it has no free ends as shown in fig. The open patterns are simply steady traces and have free ends. 

The ratio of vertical to horizontal frequencies of closed Lissajous patterns can be obtained by counting the number of positive vertical peaks and dividing it by number of positive horizontal peaks and is given by the formulae.

Lissajous patterns are used for accurate measurement of frequency of a waveform. The signal or the waveform, whose frequency is to be measured, is applied to the vertical deflection plates the CRO, an accurately calibrated standard frequency source is used to supply voltage to the horizontal deflection plate with the internal sweep generator switched off.

 

Posted Date: 7/12/2012 6:22:22 AM | Location : United States







Related Discussions:- Use of cro for frequency measurement, Assignment Help, Ask Question on Use of cro for frequency measurement, Get Answer, Expert's Help, Use of cro for frequency measurement Discussions

Write discussion on Use of cro for frequency measurement
Your posts are moderated
Related Questions
Explain BOUND instructions in 8086 family with example and their effect on flag. BOUND: The BOUND instruction, that has two operands, compares a register along with two word

Compare with Register The contents  of the register  are compared with  the contents  of the accumulator  here  register  may be  any one  of the  A, B, C, D E, H, or L  reg

Name the three modes used by the DMA processor to transfer data? The three modes are:- a) Signal transfer mode (cycling stealing mode) b) Block transfer mode c) Demand

Illustrate the working of full wave rectifier using bridge rectifier. How is it different from centre tapped Rectifier ? Illustrate Avalanche and Zener breakdown. Draw & explain

1.       In ordinary photography, each part contains information of the original object separately and in case some part of the object is destroyed then the information of that par

Systemic Requirements: A robust GIS solution for a distribution utility comprises the subsequent: GIS application and database software should be OGC (Open Geospatial

Explain temperature dependence of electrical conductivity and resistivity in conductors. When the temperature is increased, there is a greater thermal motion in atoms that redu

Defective Metering and Meter Reading Errors Defective Metering Tampered, slow running, stalled, damaged meters are a cause of huge losses to the utility. The electromecha

Change in an organisation: Change might be perceived in two ways: Change as continuous and intrinsic to an organisation and change as discontinuous & extrinsic. A force

Tick of the property, which is different from the group (A) Ductility.                (B) Resistivity. (C) Tensile strength.   (D) Hardness. Ans: Tick of the pr