The aim of this experiment is to show how to trace the lissajous figures on the cathode ray oscilloscope using two function generators connected to. Lissajious pattern to find unknown frequency duration. If the two input waveforms f equal amplitude and 90 degree phase difference is applied to the cro then the lissajous patterns obtained will be a. Describe in detail the construction and working of analog type storage oscilloscope. This frequency measurement by lissajous method techniques used are simple and dependable, and measurement may be made at any frequency in the response range of the oscilloscope. As shown in the figure, cro probe mainly consists of three blocks. A and b represent amplitudes in the x and y directions, a and b are constants, and. Pdf discrete lissajous figures and applications researchgate. In order to generate a lissajous pattern a known reference frequency sine wave is applied to one of the deflection plates of the oscilloscope and the unknown sinusoidal signal to the other deflection plates a lissajous pattern.
Using a scope to display lissajous patterns electrical. Use of lissajous patterns to calculate phase shift lissajous patterns are obtained on the scope simultaneously by applying the two sinusoidal inputs to be compared at the vertical and horizontal. Energy, vibrating particles and other invisible forces pervade our physical universe. Lissajous figures are patterns generated by the junction of a pair of sinusoidal waves with axes that are perpendicular to one another. The result of these patterns help in analyzing signal parameters. Even light part particle, part wave has a fundamen.
Lissajous figures often appeared as props in science fiction movies made during the 1950s. Inspired by sound, the first lissajous patterns were made by reflecting a beam of light in mirrors attached to two tuning forks to make a dot of light that bounced around following a lissajous curve. Lissajous 3d can make many beautiful relaxing animations. Using xy displays lab wm312 introduction lissajous patterns.
Some more uses of cro or cathode ray oscilloscope can be made up by just seeing at the situations. The values of a and b have a particularly strong effect on the shape of the curve a determines the number of horizontally aligned lobes and b determines the number of. These lissajous patterns have two applications to analysis the signals. Lissajous curves can also be generated using an oscilloscope as illustrated.
These electrons, if left undisturbed, travel in a straightline. Lissajous had a figure for it, march 1957 popular electronics. Hence, apply the sinusoidal signal, which has standard known frequency to the horizontal deflection plates of cro. A variation is the display of signals in the frequency domain.
Measurement of phase difference between two signals using dual beam cro. Learn more about homework not originally tagged as homework, triangle wave, square wave, sawtooth, lissajous. Phase measurement using lissajous patterns xy mode. Oscilloscope fundamentals case school of engineering. The lissajous lab provides you with a virtual oscilloscope which you can use to generate these patterns. In the old days, whenever they showed an engineer working, there was usually an oscilloscope nearby with a pattern on the screen. Lissajous figures with triangular and square waves in m. Cro cathode ray oscilloscope working electronics club. Lissajous figures james emery 42008 contents 1curves 1 2 program 4 1curves let xta1 sin. Frequency measurements using lissajous figures lissajous pattern also helps to measure frequency.
Straight line tilted at 45 degree with respect to xaxis b. You can also make new ones using a random mix of the parameters of all the files in a folder this tends to produce nice patterns as it uses values of the. Lissajous figures or lissajous curves are produced in two dimensions when the x and y coordinates are given by two sine waves, which may have any amplitude, frequency and phase. Frequency measurement is very important in many applications of alternating current, especially in ac power systems designed to run efficiently at one frequency and one frequency only. Phase measurement using lissajous pattern electrical and electronics measurement gate academy. Lissajous patterns at the dawn of the technological revolution. A signal of known frequency was applied to the horizontal axis of an oscilloscope, and the signal to be measured was applied to the vertical axis. If the ratio of the first frequency to the second is a rational number. Measurement of the speed of sound in air medium using. The number of vertical peaks 5 in this case and horizontal peaks 2 indicate. Cathode ray oscilloscope cro the cro stands for a cathode ray oscilloscope.
One of the quickest methods of determining frequency is by using lissajous patterns produced on a screen. Lissajous 3d trace the curves using a ribbon, or a tube, and the dot can oscillate in three or more directions, which takes the patterns. To measure the phase difference of two sine waves their frequencies must be equal. Lissajous patterns of cro or cathode ray oscilloscope electrical4u. A much wider range of lissajous figures can be created by manually adjusting the amplitude, frequency, andor phase of one or both of the voltages via the designated sliders. The aim of this experiment is to show how to trace the lissajous figures on the cathode ray oscilloscope using two function generators connected to x and y plates of cro. Figure 3 shows the patterns obtained for 8 30 and 8 30, using the simple comparator cir cuit shown in figure 4. Phase measurement using lissajous pattern electrical and electronics measurement duration. Lissajous patterns at the dawn of the technological revolution the lissajous pattern or lissajous figure is named for the french mathematician jules antoine lissajous 1.
The pattern of crisscross lines is actually a lissajous figure. The block diagram of cro probe is shown in below figure. Lissajous patterns of cro or cathode ray oscilloscope. Introduction lissajous figures displayed on an oscilloscope can be used to give a quick estimate of the relative phase of two signals at the same frequency.
In 1879, willan crooks demonstrated that the cathode rays can be deflected in a vacuum tube type by using a magnet. Coaxial cable simply connects the probe head and termination circuit. We can tell that oscilloscope can measure the phase and thefrequency reference 1. Lissajous figures article about lissajous figures by the. A labview based simulation of lissajous pattern using daq card. C signal to obtain the sinusoidal pattern and after that we do the same thing for another one. Oscilloscope fundamentals introduction nature moves in the form of a sine wave, be it an ocean wave, earthquake, sonic boom, explosion, sound through air, or the natural frequency of a body in motion. Two phaseshifted sinusoid inputs are applied to the oscilloscope in xy mode and the phase relationship between the. Cro is a very versatile instrument in laboratory for measurement of voltage, current, frequency and phase angle of any electrical quantity. Lissajous pattern trainer experiment setup electronics lab.
Cro, function generator, digital voltmeter, connecting wires. Phase measurement using lissajous pattern electrical and. Lissajous figures displayed on an oscilloscope can be used to give a quick estimate of the relative. Geometrical and graphical representations analysis of. To study the series and parallel lcr circuit and plot the resonance curve at the constant frequency.
Which makes these lissajous patterns very useful to analysis the signals applied to deflection plated of cro. Let us compute the period of this curve, assuming that. In our other articles i will try to cover this lissajous pattern in more detail. In the application of cro this lissajous pattern plays a very important role. Lissajous curves can also be generated using an oscilloscope. If the file has been modified from its original state, some details such as the timestamp may not fully reflect those of the original file. Frequency and phase measurement ac metering circuits. Lissajous pattern theory lissajous figure or lissajous pattern is the quickest way to calculate frequency and phase difference. They areproduced in an oscilloscope by connecting one signal to the vertical trace and the other tothe horizontal trace. The alternative way of using oscilloscope to measure frequency. It is a device which is used for showing the signals on the screen. Using similar approach we can easily obtain the lissajous patterns for,, and as shown in fig. Here is a sampling of lissajous figures for two sinewave signals of equal frequency, shown as they would appear on the face ofan oscilloscope an ac voltagemeasuring instrument using a crt as.
Circuit diagram an oscilloscope is a measuring device used commonly for. Shape of these lissajous pattern changes with changes of phase difference between signal and ration of frequencies applied to the deflection plates traces of cro. This file contains additional information such as exif metadata which may have been added by the digital camera, scanner, or software program used to create or digitize it. In most oscilloscopes that have this capability, the frequency domain is accessed by pressing a button labeled math. Lissajous work in the nineteenth century centered around the study of vibrating objects and wave phenomena. Pdf oscilloscope and its applications researchgate. Measurements using lissajous figures tutorialspoint. Those are probe head, coaxial cable and termination circuit. The resulting pattern was a function of the ies 8, 9. Storage oscilloscopes, capable of high persistence phosphors, have many applications. The merits of the proposed scheme in comparison with a measurement based on the conventional lissajous pattern are the following.
This feature applies magnetism to any of the lissajous patterns, so transforming it you can also add an initial velocity to the pattern. Lissajous figures are obtained with an oscilloscope when this is. Lissajous figures and cro setup to obtain lissajous figures. The most common use of an oscilloscope is to display one or more signals in the time domain. The user interface above allows you to modify each of these five parameters and see how the graph is affected. By howard burgess centuryold light pattern now serves as electronic yardstick men are traditionally attracted by figures with curves. An important electrical quantity with no equivalent in dc circuits is frequency. A certain frenchman named lissajous, who lived around 1855, was no exception.
The applet also allows you to apply a signal to modulate the hue of the trace, so you can create colorful designs. Frequency measurement by lissajous method basic circuit. This is a support page to the multimedia chapter interference and consonance in the volume waves and sound, which introduces interactions between sine waves. Theoretical approach the scheme of the acoustic interferometer is. Two obtain lissajous figure we need two function generator and a cro. Shape of these lissajous pattern changes with changes of phase difference between signal and ration of frequencies applied to the deflection. Named after jules antoine lissajous, a lissajous curve. An octopus circuit can be used to demonstrate the waveform images on an oscilloscope. Cro setup to obtain lissajous figures figure1 depicts lissajous figure obtained on cro using. Lecroy corporation using xy displays page 2 of 5 the user can select which waveform is connected to the vertical axis and which is associated with the horizontal axis. Phase measurements using lissajous figures lissajous figures are sometimes used for the measurement of phase. Connect the output of phase shift network to the vertical input as shown in figure. For a ratio of 1, the figure is an ellipse, with special cases including circles a b. From the shape of lissajous pattern displayed on cro screen, one can determine information about relative phases of signals and frequency ratio of signals too.