Lab 1
- John Ragland
- Sep 7, 2017
- 2 min read
Test and Measurements
Simple Sine Waves
The main goal of this lab is to practice using the lab equipment that will be used throughout the semester.
In the first exercise, I used the 3311A function generator to created a 10 kHz sine wave with amplitude 1 V. This wave was viewed on the oscilloscope. Different things were measured on the oscilliscope such as a moving average, the peak to peak value, and the measured frequency of the signal. A DMM was used to measure the AC voltage of the signal. The measured value was 0.73 V. This makes sense because this is the RMS value of a 1 V amplitude sine wave. These measurements were then repeated using BK Precision 4040 function generator. Figure 1 shows the oscilliscope when reading the signal from the BK Precision 4040 function generator.
Figure 1: Signal from Precision 4040 function generator
Amplitude Modulation
In this section the BK Precision 4040 function generator was used to create an amplitude modulated signal. At first internal modulation was used. This is limited to encoding a 1 kHz signal.
To create a signal that has a different encoded signal than 1 kHz, I used the external modulation option on the 4040 function generator and the 3311A function generator as the external source. Figure 2 shows the resulting signal that was generated with this technique.
Figure 2: AM Signal Generated with Precision 4040 Modulation with External Signal
Next, an FFT was used with the scope to look at the frequency spectrum of the AM signal. The expected result should be a large peak at the carrier frequency and two smaller peaks offset from the carrier frequency by the information frequency. Figure 3 shows the this FFT result.
Figure 3: FFT of AM Signal
Tables 1 and 2 were then created using data from ~50% modulation and ~100% modulation signals.
Conclusion
In this lab the functionality of the tools that will be used this semester were learned. I learned about basic use and operation of the oscilloscope, how to generate function and AM signals, and how to compute the FFT of a signal within the Oscilloscope.
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