Cathode Ray Oscilloscope CRO

Cathode Ray Oscilloscope CRO

1. CATHODE RAY OSCILLOSCOPE

2. TOPICS COVERED Introduction to CRO Block diagram of CRO Detailed description of CRT Multi –Input Oscilloscope Lissajous Patterns Types of Oscilloscope and it’s application

3. HOW A CRO LOOKS LIKE

4. INTRODUCTION TO CRO Versatile electronic instrument giving visual display of signals Used for measurement of frequency , amplitude, phase etc. Also used in determining the nature and characteristics of various components. Has a high bandwidth range thus making it a sensitive and accurate device. Easier to use as the internal routine act as a guide to the user.

5. BASIC DIAGRAM

6. ANOTHER SCOOP….

7. WORKING OF A CRO

8. Cathode ray tube The main parts of Cathode Ray Tube are : Electron Gun Assembly Focusing Anodes Deflection Plates Assembly Screen for CRT

9. Electron Gun

10. Anodes

11. Deflection Plates

12. Fluorescent Screen

13. Multi-Input Oscilloscope Oscilloscope can have multiple input and display facilities.

14. The most common one is of - TWO INPUTS . Although FOUR and EIGHT inputs are available for special applications

15. There are primary two types of multi-input oscilloscope :- Single Beam Oscilloscope Dual Beam Oscilloscope Both of them can be converted into a further Number of traces .

16. Dual Trace Oscilloscopes

17. In this oscilloscope two separate vertical input channels are used. There are two common operating modes for the Electronic Switch , called Alternate and Chop which can be selected from the instrument’s front panel. Dual Trace Oscilloscopes

18. BLOCK DIAGRAM

19. Dual Beam Oscilloscope The Dual Beam Oscilloscope has two separate electron beams , and therefore two completely separate vertical channels .

20. There are two methods used for generating the two electron beams within the CRT. The first method is :- Double gun tube Split Beam

21. Multiple input CRO works in following two modes alternate mode chopped mode

22. Alternate mode In alternate mode the an electronic switch alternates between sig A & B.

23. Waveform in alternate mode

24. Chopped mode In the chopped mode the switch free runs at very high frequency.

25. Waveform of Chopped Mode

26. Pattern When two sinusoidal voltage signals of equal frequency having some phase difference are applied to the deflection plates of CRO, a straight line or an ellipse appears on the screen these figures are called Lissajous figures or Lissajous curves or pattern.

27. Some examples of lissajous figures……..

28. With the help of lissajous figures we can measure……. Frequency Phase

29. Frequency Measurement Fx / Fy = Hp/ Vp Fx = Unknown frequency Fy = K nown frequency Hp = Points on horizontal tangencies Vp = Points on vertical tangencies

30. Phase Measurement sin Ф = c/b

31. Digital Storage Oscilloscope

32. BLOCK DIAGRAM OF DSO

33. Advantage Of DSO Stores waveform for infinite time Digitize waveform can be processed in any way Writing speed is more Processing of signal is easy

34. Analog Storage Oscilloscope

35. Trace storage is an extra feature They used direct-view storage CRTs The storage is accomplished using the principle of  secondary emission Briefings

36. Data can be stored to infinite time Image quality is good Writing speed is high Processing of signal is easy Data can be stored for finite time Image quality is not poor Writing speed is poor Processing of signal is difficult Difference between ASO & DSO DSO ASO

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