Question

As the periodic signal display on a spectrum analysis as a signal vertical line.What would the signal look like on an oscilloscope

Answer 1

An oscilloscope's primary function is to provide a graph of a signal's voltage over time. This is useful for measuring such things as clock frequencies, duty cycles of pulse-width-modulated signals, propagation delay, or signal rise and fall times. It can also alert you to the presence of glitches in your logic or bouncing switches.

This tutorial is meant as a simple, interactive tutorial to get you to the point where you can use the basic features of an oscilloscope. More details are available in the manual. In particular, you should look at the "Application Examples" section and the "Front-Panel Menus and Controls" sub-section of the "Getting Started" section. But if you're reading this tutorial, that probably means you'd rather not read the manual, so let's get started.

Build a circuit to test and hook up the probes



An oscilloscope is for looking at the behavior of a circuit, so the first step is to build a circuit and hook up probes. You'll be building the circuit on the right. Some things to know:

Good values for the resistor and capacitor are 430K Ohm and 0.002uF, respectively

On the function generator cable, the red clip is the generated signal, and the black clip is ground

If your function generator has multiple outputs, use channel 1

The oscilloscope probes have a clip coming off the side, this should always be connected to ground

The tip of the oscilloscope should be connected to the signal you want to look at. If you would rather use a pin tip instead of the hook tip, you can pull the hook tip sheath off. Do not unscrew the tip or attempt to unscrew the sheath!

Power on the Function Generator

The function generators in the lab are Tektronix AFG310 and AFG320 function generators. The AFG310 has a single signal output, and the AFG320 has two. We'll only be using one of the outputs, so either one is fine. They look like the ones in this picture taken from Tektronix's website: 

At this point, you can power on your function generator. It should come up in a reset state, so simply follow the following steps to make it produce a 1kHz square wave that goes from +1 to -1 volts:

Hit the "FUNC" button to select a function

Hit the up arrow so that the function type is "SQUA"

Hit Enter

Hit the "FREQ" button to select the frequency

Hit 1

Hit "kHz/ms/mV"

Hit Enter

Hit the Channel 1 button

At this point, the function generator should be producing the desired square wave out its channel 1 output.

The Basic Oscilloscope Controls

The oscillocopes we have are Tektronix TDS3032 and TDS3034B oscilloscopes. The TDS3032 has two input channels; the rightmost bnc plug is for an external trigger that we won't be using in this tutorial. The TDS3034B has 4 input channels. They both have very similar controls that can be grouped into 6 basic groups:

VERTICAL - Controls the vertical alignment of the traces as well as which traces are shown, their scale, which one is the selected one, etc. Note that only the currently selected trace will be affected by the controls in this group.

HORIZONTAL - Controls the time scale and position. Note that all traces are affected simultaneously by these controls.

TRIGGER - Controls the triggering. This is useful for horizontally aligning a repeating signal with itself.

ACQUIRE - Controls the method of aquiring samples. It also has the autoset button that will cause the oscilloscope to autmatically choose settings for all the other controls that it thinks will best display the current waveforms. This is a very useful button, but I have found it chooses good values about 80% of the time.

Miscellaneous - This section is the unlabled set of controls that is at the top of the control panel. The controls in this section are mostly high level functions that are not specific to a given waveform. It is in this section that you find the "General Purpose Knob" referred to later.

Selector buttons along the right and bottom of the screen (not shown in picutre) - These are used to select from menus that appear on the bottom and right of the screen, just like you would do with an ATM machine at the bank.



Resetting the default settings

The oscilloscopes remember their last state before they were turned off, so you'll want to reset it to the factory defaults before continuing. The following steps will reset the oscilloscope to the default state:

Hit the "Save/Recall" button

Select "Recall Factory Setup" from the items at the bottom of the screen

Select "OK Confirm Factory Init" from the items at the right of the screen

Hit the "Menu Off" button

At this point, you should see a yellow square wave in the middle of the screen. This is the signal coming in on channel 1.

Displaying Traces

You've also got a signal coming in on channel 2, so you'll want to make it display. Do this by hitting the "Ch 2" button. Now, channel 2 is also displayed, but it's aligned on top of the channel 1 data. Fix this by hitting the "Autoset" button. At this point, you should have a screen that looks something like this: