Using An Oscilloscope
What Is An Oscilloscope Used For?
What Is An Oscilloscope?
How Do You Use An Oscilloscope?
Displaying a Signal from a Function Generator

What is an oscilloscope used for?         The oscilloscope is the most powerful instrument in our arsenal of electronic instruments.  It is widely used for measurement of time-varying signals.  Any time you have a signal that varies with time - slowly or quickly - you can use an oscilloscope to measure it - to look at it, and to find any unexpected features in it.

        The features you see in a signal when you use an oscilloscope to look at a signal are features you cannot see otherwise.  In this lesson you will learn about oscilloscopes and you should keep this goal in mind as you proceed through the lesson.

Given a time varying signal that you need information about,
Be able to use an oscilloscope to portray the signal as a function of time.
Be able to measure signal parameters with an oscilloscope.

What does an oscilloscope look like?

        Note the following features of the oscillscope


How do you use an oscilloscope?
Showing a Simple Signal on the Scope

        To get familiar with the scope, you can show a sine signal on the scope.  We're going to ask that you show a signal with the following characteristics


What will the signal look like?

        The oscilloscope has an illuminated dot that moves across the screen.  With no signal, it would look like the following.

When a sinusoidal signal is applied, then the vertical position is proportional to the voltage at any instant.  If you applied a low frequency sine signal, you would get a track like the one below.

        If you have a sinusoidal signal that repeats every half millisecond - a frequency of 2kHz - you would get a picture like this one.  It would appear to be stationary on the oscilloscope screen, but it really isn't.  It's just that it repeats so frequently that you see it as a constant image.


Simulation

        In this simulation, a simulated function generator is connected to a simulated oscillscope.  Both are simplified versions of real instruments.  Note the following.

Notice the following in this simulation.


Clearly you cannot trigger an oscilloscope by hitting a button every time you want to observe a new trace on an oscilloscope.  Another alternative might be to let the oscilloscope free-run.  In other words, let the oscilloscope start another trace as soon as a trace is finished.  Here is a simulation of that situation.
Simulation - Free Running Oscillscope

        In this simulation, the signal trace begins anew as soon as it reaches the right hand side of the oscilloscope screen.

Notice the following about this situation.
Note the following about what happens when the sweep speed changes.

        In a real oscilloscope, the trigger signal can be generated when the signal value reaches some particular level - the trigger level.  In most cases you can set the trigger level to a voltage value of your choosing.



        Now that you have had a chance to experiment with the simulations above, it's time to define a few terms - and these are items you can control on most oscillscope.
Problems

P1   In this simulation, determine the sweep speed.  Note that the grid lines are all 1 cm apart.  (Your monitor setting might change the scale!  Assume that the grid lines are all 1 cm apart.)

Enter your answer in the box below, then click the button to submit your answer.  You will get a grade on a 0 (completely wrong) to 100 (perfectly accurate answer) scale.

Your grade is:

P2   What is the vertical sensitivity of the simulated oscillscope?
Enter your answer in the box below, then click the button to submit your answer.

Your grade is:


        Here is another kind of question.
Question

Q1   You have a signal that is somewhere in the neighborhood of 100 KHz.  That's a period of 10 msec. The oscilloscope screen is 10 cm wide.  What sweep setting would you use if you wanted to display a few cycles of your signal across the screen?



Lab Problem