Difference Between Digital & Analogue Oscilloscopes

An oscilloscope is a laboratory instrument commonly used to display and analyse the waveform of electronic signals. In effect, the device draws a graph of the instantaneous signal voltage as a function of time. The two basic types of oscilloscope are digital and analogue.

While they might work slightly differently, you will find that the digital and analogue oscilloscopes more or less do the same thing. The different parts are essentially the same and they even have similar displays, so if you’ve been using one, you should not have much trouble adapting to the other. Each type of oscilloscope has its own strengths and weaknesses, which we will be outlining in this post.

Parts of an Oscilloscope

There are three sections on the front panel of an oscilloscope: display, time base and channels. Each device has a display that is either a cathode ray tube (CRT, like older large-form televisions) or liquid crystal display (LCD, like some newer, flat panel televisions). With the time base, you can control the time position of the waveform to view different portions of the signal. The channel control is used for analysing the different input signals.

Sample Rate

Sample rate determines the maximum resolution at which you can view waveforms. The digital oscilloscopes are capable of a much higher sample rate than you will find with any of the analogue scopes. This means you can view a signal more closely, more accurately and it should be easier for you to make some of the smaller and finer adjustments.

Memory

Another area where you will see a difference is in terms of memory. The memory is the determining factor when trying to see just how much of a waveform you are going to be able to capture. Greater memory, naturally, is a good thing, meaning you can analyse a longer signal, or more signals at one time. The digital models come out top again, as they are capable of carrying larger amounts of memory than the analogue options.

Connection Options

A big difference that also gives digital scopes an advantage is that they often come equipped with a high speed USB 2.0 port. This means that you are able to connect your device to your computer and save information to analyse.

Advantages of an Analogue Oscilloscope

While it could be argued that the digital oscilloscope does have the advantage in many ways, the analogue scope does have some pros.

You may find that it is easier to analyse real time signals because you have the ability to adjust the focus and intensity of the display for a clearer screen view. Analogue models also include a function called "intensity grading," which automatically highlights anomalies in the signal, making it easier to notice problems.

Typically, modern high-end oscilloscopes are digital devices. They connect to personal computers and use their displays. Although these machines no longer employ scanning electron beams to generate images of waveforms in the manner of the old cathode-ray "scope," the basic principle is the same. Take the time to look at the specifications and characteristics of both and simply choose the one you feel most comfortable with.

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