Looking at some oscilloscopes

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In summary: There are a few key things to consider when selecting a dual trace oscilloscope. First, the bandwidth of the oscilloscope is important as it determines the frequencies it is capable of displaying. A 20 MHz oscilloscope will only display signals at or below 20 MHz, while a 100 MHz oscilloscope can display higher frequencies more accurately. Additionally, a higher bandwidth oscilloscope is generally better for displaying signals with higher frequencies, such as square waves. Overall, the 100 MHz oscilloscope would be considered better than the 20 MHz oscilloscope unless the signals being studied are all of very low frequency.
  • #1
physmurf
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Hi, I am looking at some oscilloscopes for a class I will be teaching. What should I look for when selecting a dual trace oscilloscope? What are the key differences between a 20MHz and a 100MHz oscilloscope? Is the 100 better than the 20?

Thanks!
 
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  • #2
Honestly, if you don't know what the difference is between a "20 MHz" and "100 MHz" oscilloscope, you probably don't even know how to use one, and therefore probably aren't really in a position to be purchasing them. Besides, I strongly doubt that anyone actually manufactures a 20 MHz oscilloscope anymore. (Agilent's crappiest model is 60 MHz.) Is this really just a homework problem? If so, please use the homework help forum; you don't need to "trick us" into helping you.

The numbers 20 and 100 MHz refer to the bandwidth of the oscilloscope. A 20 MHz oscilloscope is only capable of displaying signals with frequencies at or below 20 MHz. (The bandwidth is usually given at the -3 dB point, meaning that an oscilloscope with a bandwidth of 20 MHz will will actually attenuate a 20 MHz signal by 3 dB, or 50%. Signals with eve higher frequencies will be attenuated much more than 3 dB.)

Obviously, an oscilloscope with a higher bandwidth is better than one with a lower bandwidth, unless the signals you're interested in exploring are all of very low frequency.

Note that square waves and the like are composed of sinusoids of various frequencies added together, and a 20 MHz square wave will require at least 100 MHz bandwidth to be displayed reasonably accurately on the oscilloscope's screen.

- Warren
 
  • #3


When selecting a dual trace oscilloscope, there are a few key features to consider. First, you should look for a high bandwidth, preferably at least 100MHz, as this will allow for more accurate and detailed measurements. Additionally, it is important to consider the sample rate, which should be at least 2.5 times the bandwidth in order to accurately capture signals. Another important feature is the number of channels, as having more channels allows for the measurement of multiple signals simultaneously.

The key differences between a 20MHz and a 100MHz oscilloscope lie in their bandwidth and sample rate. A 100MHz oscilloscope will have a higher bandwidth and sample rate, meaning it can accurately measure higher frequency signals and capture more detail in the waveform. However, this does not necessarily mean that the 100MHz oscilloscope is better than the 20MHz. It ultimately depends on the specific needs and applications for the oscilloscope. For lower frequency signals, a 20MHz oscilloscope may be sufficient, while for more complex and high frequency signals, a 100MHz oscilloscope would be a better choice.

In summary, when selecting a dual trace oscilloscope, it is important to consider the bandwidth, sample rate, and number of channels. The key differences between a 20MHz and 100MHz oscilloscope lie in their ability to accurately measure higher frequency signals and capture more detail. Ultimately, the best choice will depend on the specific needs and applications for the oscilloscope.
 

1. What is an oscilloscope and how does it work?

An oscilloscope is a scientific instrument used to measure and display electrical signals over time. It works by displaying the voltage of an electrical signal on a graph, with time on the horizontal axis and voltage on the vertical axis. This allows scientists to visualize and analyze the characteristics of electrical signals.

2. What are the different types of oscilloscopes?

There are several types of oscilloscopes, including analog, digital, and mixed-signal. Analog oscilloscopes use cathode ray tubes (CRTs) to display the signal, while digital oscilloscopes use digital processors and LCD screens. Mixed-signal oscilloscopes combine the features of both analog and digital oscilloscopes.

3. What are the key features to consider when choosing an oscilloscope?

Some important features to consider when choosing an oscilloscope include bandwidth, sampling rate, number of channels, and memory depth. Bandwidth determines the range of frequencies that the oscilloscope can accurately measure, while sampling rate determines the number of data points that can be captured per second. The number of channels refers to the number of signals that can be measured simultaneously, and memory depth determines how much data can be stored for analysis.

4. How do oscilloscopes help in scientific research and experiments?

Oscilloscopes are essential tools for scientists as they allow for the visualization and measurement of electrical signals in experiments and research. They can help in analyzing the characteristics of signals, detecting abnormalities, and troubleshooting circuits. Oscilloscopes are also useful in a wide range of fields, including physics, engineering, and medicine.

5. Can oscilloscopes be used for more than just measuring electrical signals?

Yes, oscilloscopes have a variety of applications beyond measuring electrical signals. They can also be used for testing and troubleshooting electronic devices, analyzing audio signals, and even measuring mechanical vibrations. Some oscilloscopes also have the ability to measure other parameters such as frequency, phase, and temperature.

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