Oscilloscopes

Table of Contents


What is an Oscilloscope?

An oscilloscope is a test equipment device that is usually used to test or diagnose electrical circuits by graphically displaying how the voltage changes over time [1], although some are able to measure other properties such as current. Voltages, called signals, coming into the scope have their voltage levels represented on the vertical axis and time on the horizontal axis, and such a representation allows for the circuit's behaviour to be tested [1]. There are two main types of oscilloscopes: analog, and digital.



Oscilloscope Systems

  • The vertical system controls the vertical properties of the waveform such as the vertical scale and position, and can set other properties such as the bandwidth limit [1].
  • The horizontal system controls the horizontal properties of the waveform such as the horizontal scale and position, and can be used to find other properties such as the sample rate [1].
  • The trigger system helps stabilize waveforms and isolate a frame of the waveform [1].
  • The probe collects the data for the oscilloscope. The probe's ground clip is attached to the circuit's ground and the tip of the probe measures voltage [1].


Analog Oscilloscope

  • CRT oscilloscopes are common and are called Cathode Ray Oscilloscopes [2]
  • Waveform is shown in its original form [2]
  • Useful for applications where precision is not as important [2]
  • Since they are so old, they generally have less features than modern digital oscilloscopes
  • Generally lower in cost as analog oscilloscopes are not very common nowadays, and most that are sold are old and used
Analog Oscilloscope [2]

An image of an analog oscilloscope.


Digital Oscilloscope

  • Uses LCD display [1]
  • Converts the analog signal to a digital stream using an analog-to-digital convertor before displaying to the screen [2]
  • Useful for measuring high frequency signals [2]
  • Useful for complex waveforms [3]
  • More expensive than analog oscilloscopes [2]
  • Can automatically store measurements to export and analyze data [3]
  • Some forms include handheld, PC-based, and benchtop oscilloscopes [2]
Digital Oscilloscope [2]

An image of a digital oscilloscope.


Selecting an Oscilloscope

  • It is recommended that an oscilloscope with a bandwidth of at least five times higher than the input waveform is used [2]
  • For a digital oscilloscope, it is recommended that an oscilloscope with a sampling rate at least five times the maximum frequency is used [2]
  • For digital oscilloscopes, an 8 bit resolution is useful for low-end applications, whereas higher-end applications might require 12 or 16 bit resolutions [2]


Oscilloscope Applications

  • Can be used to analyze basic characteristics of circuits and other devices [4]
  • Can be used to analyze serial data such as USB [4]
  • Useful for analyzing and debugging signal jitter [4]
  • Can be used to perform time-domain reflectometry [4]


References

[1] Todd, "What is an Oscilloscope? Why is it important?," 30 January 2020. [Online]. Available: https://www.circuitspecialists.com/blog/what-is-an-oscilloscope/. [Accessed 13 April 2021].

[2] John, "Analog Oscilloscope vs Digital Oscilloscope," [Online]. Available: https://www.circuitstoday.com/analog-oscilloscope-vs-digital-oscilloscope. [Accessed 13 April 2021].

[3] Minis, "Differences Between Digital Oscilloscopes and Analog Oscilloscopes," 1 March 2020. [Online]. Available: https://compocket.com/blogs/news/differences-between-digital-oscilloscopes-and-online-oscilloscopes. [Accessed 13 April 2021].

[4] G. Leger, "Common Oscilloscope Applications," 22 April 2014. [Online]. Available: https://www.circuitspecialists.com/blog/oscilloscope-applications/. [Accessed 13 April 2021].

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