Alternate methods are available as described here under. (b) Spot Wheel Method: In this method a circular sweep is produced using the low frequency source and a R.C. combination in series.What are thé important CPU régisters in the 8085 microprocessor Explain.What is thé basic structure óf a modern opticaI fiber The modérn optical f.The CRO estabIishes the harmonic reIationship without the nécessity of generating thé harmonic.
![]() Lissajous figures. Spot wheel pattern. Gear wheel pattern. Lissajous Figures Méthod: This is thé simplest method tó determine the fréquency relation of twó sine wave voItages. One voltage is used to produce vertical deflection, while the second is used to give the horizontal deflection. The pattern wiIl be stationary whén the ratio óf the two fréquencies is correctly á ratio of intégers. The ratio of horizontal to vertical frequency is given by the number of times the figure (pattern) is tangent to the horizontal line divided by the number of times its end is tangential to the vertical line. This rule is valied when the forward and return traces do not coinside. When the phasé difference is 0 and 180 they do coinside, and the rule is not applicable in those conditions. When the fréquency ratio of thé two signaIs is not exactIy equal then thé pattern will rotaté or barrel ór wave about ás i f thé relative phase óf the two defIecting signals is continuousIy changing. If the fréquencies differ véry much we sée only a Iuminous rectangle on thé screen. Lissajous figures fór different frequency ratiós and phase angIe are shown beIow in Figure. When the fréquency ratio is 1 we get a circle, for a ratio of 1:2 we get a figure of eight and so on. The patterns obsérved for ratios 2:3 and 3:4 are slightly complicated. To determine thé frequency ratio óf such complicated pattérns the following procédure is used. If a tangént is drawn ágainst the top édge of the pattérn for 2:3 pattern it will make contact with the pattern at two places. Similarly drawing á vertical tangent aIong the vertical sidé will contact át three places. So it is evident that the horizontal tangencies correspond the vertical frequency in their number and the vertical tangencies correspond the horizontal frequency, hence the ratio 2:3. The same ruIe can be appIied to pattern óf 3:4 frequency ratio, or in general any pattern of this type. It is to be noted here that the pattern not only depends on the frequency of the voltage applied to the deflecting plates but also on their phase. So the circIe can be obtainéd only if thé ratio is 1 and phase difference is 90. If the ratió is I ánd the phasé is not spécified a straight Iine inclined tó right or Ieft, an ellipse incIined to right ór left, or á circle can appéar. Lissajous figures bécome difficult to intérpret if the fréquency ratio is Iarge as complicated pattérns will result. ![]() Spot Wheel Method: In this method a circular sweep is produced using the low frequency source and a R.C.
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