Abstract
The purpose of this lab was to allow for an introduction to the waveform generator and the oscilloscope. The lab helped in attaining visual representations of sinusoidal and pulse waveforms. Generating and displaying theses waveforms on the oscilloscope helped with the understanding of how this equipment works and what happens to waves when you change their period or frequency. Working with the oscilloscope helped prove that there is a direct relationship between frequency and period, and that T (period) of the wave is indeed equal to 1 divided by the frequency (f) of the wave [T = 1/f]. This lab also aided in the understanding that these waveforms are being created by electrical fields, those of which we will be studying and creating throughout this course.

Methods/Procedure
System Under Test: Using the waveform generator and oscilloscope to test the effects on sinusoidal and pulse waveforms when there is a fluctuation or change in the wave’s type, period, frequency, offset, amplitude, duty cycle or modulation depth.

Equipment Needed:
AFG1000 Series/Function/Arbitrary Waveform Generator
TBS2000 Series Oscilloscope
BNC Cable

Test Procedure:
Lab Exercise #1: (see reference page for AFG1000 Series/Function/Arbitrary Waveform Generator)

1. Push the power button to turn on the instrument
2. Press the Mod button and push the bezel button to select the continuous mode
   3.Select the Sine waveform
   4.Use the front-panel bezel buttons on the instrument to select a waveform parameter
3. Select frequency as the parameter to be changed
4. Change the frequency value of the waveform generator to 100 kHz using the numeric keypad
5. Record the period of the sine waveform
6. Change the amplitude of the sine waveform to 5V peak-to-peak. Adjust the offset to zero
7. Adjust the offset to 2.5V. Describe the change in the waveform
8. Select the Pulse waveform
9. Using the general-purpose knob change the period to 100 µs use the Width/DutyCyc and adjust the duty cycle to 10%. Record the Frequency
10. Go back and select a 100 kHz sine waveform
11. Use the Mod button to select the modulation mode
12. Select AM (amplitude modulation)
13. Press Source and select Internal
14. Press Shape and select Sine
15. Select Depth of 100%
16. Press AM Frequency and select 10 kHz
17. Change the dept to 50%. Describe the change
18. Change modulation waveform by pressing Shape and selecting Ramp

Lab Exercise #2:

1. Switch on the waveform generator’s output 1 by pushing its ON/OFF button
2. Using the BNC cable connect waveform generator’s output to channel 1 of the scope
3. Select the Sine waveform on the waveform generator and set the frequency to 100 kHz. Use the default amplitude and offset
4. Display waveform on scope. Measure frequency, period and amplitude using the scope’s measurement process.
5. Change the waveform to a Pulse waveform with a frequency of 10 kHz and duty cycle of 10%
6. Display the waveform on the scope. Measure period and amplitude of the pulse waveform on the scope
7. Use the Mod button on the function generator to create a 100 kHz sine wave form AM modulated by sine wave of frequency 10 kHz. Select modulation depth of 100%
8. Display and record the waveform on the scope

Table 1: Test Matrix (Lab exercise #1)
Period Amplitude
(peak-to-peak) Frequency Sine/Pulse
wave Duty Cycle Offset
10 µs 5V 100 kHz Sine 5% 0V
100µs 5V 10 kHz Pulse 10% 2.5V

Experimental Results
In testing the waveforms of sinusoidal and pulse waves, the findings were such that even if the values are set by the user and constant, the period, amplitude and frequency measured have the possibility of varying even if just by a hundredth of a point. Another discovery from the wave forms was that upon the offset of the wave. When increasing the offset from 0 to 2.5 volts, the period, amplitude and frequency of the waves did not change, however its position on the Y axis did. The fluctuation in depth of the sinusoidal wave at 50% versus at 100% was all but a difference in amplitude. A depth of 50% had the sinusoidal wave fluctuating between 1.25V and 3.75V, giving the wave an amplitude of 2.5V. Whereas at 100% the wave fluctuated between 0V and 5V, giving the wave an amplitude of 5V. Changes in waveform modulation created changes in amplitude.

Table 2: Measured Readings (Lab exercise 2)
Period Amplitude
(peak-to-peak) Frequency Sine/Pulse
wave Duty Cycle Offset
~ 10.02µs
(measured) ~ 4.95V
(measured) ~ 99.72 kHz Sine 5% 2.5V
~ 100.1 µs
(measured) ~ 4.900 V
(measured) ~ 9.984 kHz Pulse 10% 0V
~ 10.03 µs
(measured) ~ 5.05V
(measured) ~ 100.2 kHz Sine 10% 0V

Figure 1. Sinusoidal waveform representing the third row of Table 2.

Figure 2. A pulse waveform representing the fourth row of Table 2.

Figure 3. A sinusoidal waveform representing step seven from testing procedures and row five in Table 2.

Discussion of Important Results
The values from Table 1 are the ideal or predicted values for the amplitude, period, frequency, duty cycle and offset for a sinusoidal and a pulse wave. These measurements were set and changed by using the numerical keypad of the waveform generator prior to using the BNC cable to connect the waveform generator to the oscilloscope. As you can see, the values measured from the oscilloscope, are the approximated recorded values listed in Table 2. The difference in measurement from the predicted measurement is only about a maximum of 0.10 µs for the wave period, 0.10 V for the wave amplitude, and 0.28 kHz for the frequency of the waves.

Conclusions and Connection with Theory
The oscilloscope gives much more accurate readings in terms of sinusoidal and pulse waveforms. When using the waveform generator, the measurements were the exact numerical values that had been entered on the keypad. The oscilloscope took those measurements and produced longer, more continuous waves. Where an oscilloscope’s function is to create a larger scope, this was not surprising, however very informational. Findings here were that the waveform generator does exactly that, forms waves, while the oscilloscope oscillates those waves and creates a large scope that allows in a more precise measurement of amplitude, frequency and period of the waves.

 
References

This is a reference image showing the schematic of the AFG1000 Front Panel used to obtain the waveforms throughout this laboratory experiment. Each description corresponds to the item number preceding it. The item numbers are also indicated and labeled on the schematic.
 

The oscilloscope was used to display waveforms and provide quantitative measurements of signal parameters.