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Unformatted text preview: HACETTEPE UNIVERSITY DEPARTMENT OF ELECTRICAL & ELECTRONICS ENGINEERING ELE 271 MEASUREMENT LABORATORY EXPERIMENT #6 OSCILLOSCOPE MEASUREMENTS Object : To perform amplitude, frequency, and phase measurements using a calibrated cathode ray oscilloscope and to make use of Lissajous figures for phase and frequency measurements. 1. THEORY : 1.1 Measurement of Voltage Using CRO : A voltage can be measured by noting the Y deflection produced by the voltage; using this deflection in conjunction with the Ygain setting, the voltage can be calculated as follows : V = ( no. of boxes in cm. ) x ( selected Volts/cm scale ) 1.2 Measurement of Current and Resistance Using a CRO : Using the general method, a correctly calibrated CRO can be used in conjunction with a known value of resistance R to determine the current I flowing through the resistor. 1.3 Measurement of Frequency Using a CRO : A simple method of determining the frequency of a signal is to estimate its periodic time from the trace on the screen of a CRT. However this method has limited accuracy, and should only be used where other methods are not available. To calculate the frequency of the observed signal, one has to measure the period, i.e. the time taken for 1 complete cycle, using the calibrated sweep scale. The period could be calculated by T = ( no. of squares in cm) x ( selected Time/cm scale ) Once the period T is known, the frequency is given by f (Hz)= 1/T(sec) 1.4. Measurement of Phase : 27 The calibrated time scales can be used to calculate the phase shift between two sinusoidal signals of the same frequency. If a dual trace or beam CRO is available to display the two signals simultaneously ( one of the signals is used for synchronization), both of the signals will appear in proper time perspective and the amount of time difference between the waveforms can be measured.and the amount of time difference between the waveforms can be measured....
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This note was uploaded on 05/25/2011 for the course ELECTRONIC 271 taught by Professor Ugurbaysal during the Spring '11 term at Hacettepe Üniversitesi.
 Spring '11
 UgurBaysal
 Electronics Engineering, Frequency

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