The patterns that appear at the cro screen on connecting both pairs of the deflection plates horizontal deflection plates and vertical deflection. This frequency measurement by lissajous method techniques used are simple and dependable, and measurement may be made at any frequency in. Lissajous figure can be displayed by applying two a. Lissajous patterns are the plane curves traced by a point that executes two independent harmonic motions in perpendicular directions. Also we try to replace the dso by a labview software. The frequencies of the motion are in the ratio of two integers. We can tell that the lissajous pattern are formed by twofrequency that was given. This video uses online simulation software falstad circuit simulator for creating lissajous patterns. These devices are easy to build and can be adjusted to give a variety of patterns. Frequency and phase measurement ac metering circuits. As the frequency, amplitude and phase difference are altered, different patterns are seen on the screen of the cro. Using a scope to display lissajous patterns electrical. Trigonometryfor enthusiastslissajous figures wikibooks.
Lissajous figures are obtained with an oscilloscope when this is operated in xy mode. 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. In order to accurately examine the function of a variable one needs to graph the system of parametric equations below while keeping. You can change the curves to line segments to get a string figure type effect like this.
We can tell that oscilloscope can measure the phase and thefrequency reference 1. Prior to modern computer graphics, lissajous curves were typically generated using an oscilloscope as illustrated. Faculty of engineering chulalongkorn university cathode. They illustrate one of the earliest uses to which the cro was put. All the values which are obtained by cro or dso can be easily obtained by this effort. Electronic measurement or electronic instrumentation. 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.
Lissajous patterns are formed when two sine waves are applied simultaneously to the vertical and horizontal deflecting plates of a cro. When the phase shift is 45, the lissajous pattern is an ellipse whose centerline slopes upward from left to. 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. Phy2028 practical electronics ii information lissajous figures 1 lissajous figures 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. There are a lot of videos that show lissajous patterns on youtube. We have already discussed cathode ray oscilloscope or cro. Make lissajous patterns with diy sand pendulums or light.
The oscilloscope is a sensitive indicator for frequency and phase measurements. Each cycle object is independent with controls for frequency, phase and amplitude. Lissajous patterns lissajous figures or lissajous curve. Measurement of frequency by lissajous method the oscilloscope is a sensitive indicator for frequency and phase measurements. Feb 09, 2017 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.
A known frequency f h is applied to the horizontal input, and an unknown frequency f v is applied to the vertical input. Lissajous figures and cro setup to obtain lissajous figures. Shape of these lissajous pattern changes with changes of phase difference between signal and ration of frequencies applied to the. This pattern include directions for knee high version with calf shaping and shortened sock version. Aug 11, 2016 the same lissajous pattern is displayed when the phase shift is 360, illustrating that these two phase shifts are equivalent. This video takes a fairly detailed look at the basics of lissajous patterns on an oscilloscope. This is an article about lissajous curves lissajous curves sometimes also known as lissajous figures or bowditch curves, are pretty shapes first investigated by nathaniel bowditch in 1815, and later and in much more detail by jules antoine lissajou in 1857. Lissajous setup was similar to the apparatus which is used today to project laser lightshows 6, 7.
Sep 29, 2018 lissajous patterns lissajous figures or lissajous curve lissajous pattern on cro simulation this video explains the simulation of lissajous pattern. Geometrical and graphical representations analysis of. An oscilloscoope in the xy triggered mode displays lissajous patterns which can be used to determine the status of a transistor. Sep 21, 2014 experiments based on cro the wave shapes analysis, measurement of frequency and voltage values peak to peak and rms at different ac. The lissajous pattern or lissajous figure is named for the french mathematician jules antoine lissajous 1. Lissajous work in the nineteenth century centered around the study of vibrating objects and wave phenomena. Observe lissajous patterns for different combinations of r and c values. The cathoderay oscilloscope cro is a common laboratory instrument that provides accurate time and amplitude measurements of voltage signals over a wide. Labview, daq, lissajous pattern, dso, phase difference, function generator. One example 0 12 1 11 10 2 6 7 5 9 3 8 4 the diagram shown is identical to one of the figures you can obtain with the laser. Measurement of the speed of sound in air medium using.
If the ratio of the first frequency to the second is a rational number, thena closed curve will be observed on the cro. Experiments based on cro the wave shapes analysis, measurement of frequency and voltage values peak to peak and rms at different ac. To study the series and parallel lcr circuit and plot the resonance curve at the. 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 is produced on the scren according to the frequency ration between the two signal. Lissajous pattern trainer experiment setup electronics lab. The simplest lissajous patterns appear in the oscilloscope display when the frequencies of the signals are the same, i. The lissajous patterns for other frequency ratios can be similarly drawn. Originally published in twist collective, the two versions are quite different, with different charts and photography. Geometrical and graphical representations analysis of lissajous. Mar 10, 2019 lissajous patterns are derived in the old cathode ray tubes, by feeding one sine wave signal onto the x plates, and another onto the yplates. Lissajous figures are patterns generated by the junction of a pair of sinusoidal waves with axes that are perpendicular to one another. Lissajous figures by jed margolin in the old days, whenever they showed an engineer working, there was usually an oscilloscope nearby with a pattern on the screen. In this lesson ive discussed lissajous pattern and phase angle measurement using cro.
Geometrical and graphical representations analysis of lissajous figures in rotor dynamic system hisham a. Straight line tilted at 45 degree with respect to xaxis b. The beam in some versions traces out a lopsided figure8 pattern on its side. This page can be used as a playground or learning tool to see how changing basic parameters affects the generated images. To measure unknown frequency from lissajous figures using cro. The lissajous lab provides you with a virtual oscilloscope which you can use to generate these patterns. These lissajous patterns have two applications to analysis the signals. When both pairs of the deflection plates horizontal deflection plates and vertical deflection plates of cro cathode ray oscilloscope are connected to two sinusoidal voltages, the patterns appear at cro screen are called the lissajous pattern. When two sinusoidal signals of same frequency and magnitude are applied two both pairs of deflecting plates of cro, the lissajous pattern.
Frequency measurements using lissajous figures lissajous pattern also helps. A labview based simulation of lissajous pattern using daq card. Lissajous patterns of cro or cathode ray oscilloscope electrical4u. Some of these patterns are shown in the below figure. Shape of these lissajous pattern changes with changes of phase difference between signal and ration of frequencies applied to the deflection plates. Measurement of phase difference between two signals using dual beam cro. An important electrical quantity with no equivalent in dc circuits is frequency. The result of these patterns help in analyzing signal parameters. Faculty of engineering chulalongkorn university cathoderay oscilloscope cro objectives you will be able to use an oscilloscope to measure voltage, frequency and phase on a variety of displayed waveforms introduction the oscilloscope is the basic instrument for the study of all types of waveforms. To show how such a figure can be created, consider the diagram to represent a dualaxis amusement park ride. The pattern of crisscross lines is actually a lissajous figure. A purely mechanical application of a lissajous curve with a 1, b 2 is in the driving mechanism of the mars light type of oscillating beam lamps popular with railroads in the mid1900s. Lissajous art peter elsea 112608 2 figure 1 is a basic lissajous generator.
See more ideas about parametric equation, drawing machine and curves. Care is taken such that a very high volume is not used. Dec 12, 2012 discussion in this experiment we was exposed to another function of oscilloscope which are tomeasure frequency and to measure phase angle and also to display lissajous pattern. Lissajous figures displayed on an oscilloscope can be used to give a quick estimate of the relative. A labview based simulation of lissajous pattern using daq. Ph 2022 is meant to give you a toolkit for approaching numerical and computational problems like a physicist. Originally published in twist collective, the two versions are quite different, with different charts and photography the version includes 4 foot and 8 calf circumference sizes that can be combined for a customized fit. In the system of parametric equations, the variables affect the outcome of the lissajous figure in different ways. Describe in detail the construction and working of analog type storage oscilloscope. 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. The relationship between the two signals is shown by the type of display. Or it can be used to create and save your own lissajous artwork.
In the old days, whenever they showed an engineer working, there was usually an oscilloscope nearby with a pattern on the screen. Discrete lissajous figures and applications article pdf available in ieee transactions on instrumentation and measurement 6312. A and b represent amplitudes in the x and y directions, a and b are constants, and. It is a very important oscilloscope used to analyse the waveform and measure them. Storage oscilloscopes, capable of high persistence phosphors, have many applications. Week 2 v20170314overview welcome to the rst assignment of the physics computation sequence. Aug 07, 2018 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. A pendulum that begins with two point of support can alter the periods of the pendulum as it moves on two perpendicular axis at the same time. Jules antoine lissajous 18221880 was a french physicist who. The lissajous pattern results,when sine waves are applied simultaneously to both pairs of deflection plates. Lissajous patterns at the dawn of the technological revolution. The resulting waveform due to xy arrangement of two periodic signals having different periods is known as lissajous pattern. When using an oscilloscope, we can plot one sinusoidal signal along the xaxis against another sinusoidal signal along the yaxis, the result is a lissajous figure.
Pdf discrete lissajous figures and applications researchgate. Lissajous figure, also called bowditch curve, pattern produced by the intersection of two sinusoidal curves the axes of which are at right angles to each other. Which makes these lissajous patterns very useful to analysis the signals applied to deflection plated of cro. Lissajous pattern may be constructed in the usual way and a 8 shaped pattern with two loops is obtained. If the two frequencies are unrelated, then therewill be only a patch of light observed because of the persistence of the oscilloscope screen. Hazy sea creature screen shot movie as animated gif. If the two waves do not start at the same instant we get different patterns for the same frequency ratio. Basics of lissajous patterns on an oscilloscope youtube. A lissajous curve, named after jules antoine lissajous is a graph of the following two parametric equations.
Lissajous figures article about lissajous figures by the. Lissajous patterns of cro or cathode ray oscilloscope. A lissajous pattern is produced on the screen when two sine wave voltages are applied simultaneously to both pairs of deflection plates of a cro. Various fixed geometric shapes and patterns can be produced on the oscilloscope screen by selecting the desired option from the choose a preset pulldown menu.
Frequency measurement by lissajous method basic circuit. Pdf calibrating the frequency of tuning forks by means. They modulate a laser beam along two perpendicular directions to. 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. Budgetpriced transistor testing and lissajous patterns.
One example 0 12 1 11 10 2 6 7 5 9 3 8 4 the diagram shown is identical to one of the figures you can obtain with the laser lissajous device. Lissajous figures are obtained with an oscilloscope when this is. The applet also allows you to apply a signal to modulate the hue of the trace, so you can create colorful designs. Some lowspeed waveforms are used so that the trace movement that draws the lissajous figures can be seen and understood. On the other hand, if the frequencies are commensurable, the figure is closed and strictly periodic. See frequency measurement, oscilloscope, phaseangle measurement. When this condition is met and when the phase shift is 0, the display consists of a straight line sloping upward from the left side of the screen to the right side. Aug 25, 2016 the simplest lissajous patterns appear in the oscilloscope display when the frequencies of the signals are the same, i. These tests take place using an octopus, which eliminates problems associated with testing components that are in a circuit board. Multivariate polynomial interpolation on lissajouschebyshev. Before the days of digital frequency meters and phaselocked loops, lissajous figures were used to. First studied by the american mathematician nathaniel bowditch in 1815, the curves were investigated independently by the french. Lissajous figures or patterns are named in honor of the french scientist who first obtained them geometrically and optically. Now here we will discuss how the measurement of waveform i.
Let us now assume two harmonic waves moving along two perpendicular directions given by 1. Let us compute the period of this curve, assuming that. Liassajou curves are described by the parametric equations below. Lissajous figures james emery 42008 contents 1curves 1 2 program 4 1curves let xta1 sin. When the phase shift is 90 or 270, and both signals are the same frequency, a perfect circle displays. Lissajous figures where a 1, b n n is a natural number and. Cro until a clear trace probably elliptical is obtained on the cro s screen.
161 1246 362 1549 1444 198 1555 911 1243 1654 376 455 247 851 413 1218 136 741 379 1553 169 209 1493 197 1246 801 198 348 1152 735 324 62 347 981 75 611 22 1013 1068 60 971 1101