Lab 1 - Test and Measurement
- jpw0048
- Sep 11, 2016
- 2 min read
The purpose of Lab 1 was to introduce us to radio lab and familiarize us with the lab test equipment that will be used throughout the semester. We generated and measured sine waves and AM signals.
In lab lecture we were introduced to our TA's and went over what is expected of us this semester. We were introduced to the basic components and operation of an AM radio, as well as the process of AM signal transmission.
Firstly, we used the 3311A function generator to generate a simple sine wave and viewed it on the TDS2022 oscilloscope. To get amalgamated to the equipment, I played around with some of the function generator features such as auto-set, acquire, and cursors. I also learned how to adjust the generator to obtain a given frequency. I generated a 10kHz sine wave with a 1V amplitude with the 3311A and displayed it on the TDS2022 as shown below. Measuring the output voltage of the function generator with a DMM, I got a reading of 0.66 V:
Figure 1: 10kHz, 1V sinusoid
Figure 2: Function Generator Output Voltage
Next, I produced an AM signal using the 2022 scope and the 4040 function generator. With internal modulation we are limited to a 1 kHz signal, so I used to 3311 as an external modulation source supplying the 4040 function generator.
Figure 3: AM signal with 50% modulation
In order to look at the AM signal in more detail, I used the FFT feature of the oscilloscope. Following instructions in the lab manual, I adjusted the function generator and scope, recording the spectrum information for 50% and 100% modulation. Results show that only the dB level of the sidebands changed with percent modulation. A screenshot of the tables from the lab manual showing spectrum results and voltage amplitudes is given below.
Figure 4: Spectrum Information for 50% and 100% modulation
I am used to using the digital scope in the digitron lab, so the scope was somewhat confusing at first. Taking some extra time to play with the settings and features of the scope and function generator was helpful.
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