Analog vs Digital Oscilloscopes

Oscilloscopes are valuable test instruments used for the measurement and analysis of electronic signals. They are one of the main instruments used for the troubleshooting of electrical circuits found in televisions, computers and nearly any electronic piece of equipment.

Oscilloscopes are usually classified into two categories, analog or digital oscilloscopes. Each type of oscilloscope has its advantages and disadvantages and the proper oscilloscope should be selected based on the type of circuit and measurement being taken.

Analog Oscilloscopes

Analog Oscilloscopes capture the signal and use amplifiers to project the waveform on a luminous phosphor Cathode Ray Tube (CRT) display. The signal is minimally processed and the raw waveform is shown on the display. They are best used for analog signals that come from audio or video circuits.

The CRT displays are large, heavy and require a large amount of power to operate. However, their images are crisp and clear and the waveform can be seen in great detail by using the focus and intensity controls.

Analog Oscilloscopes are easy to use as there are relatively few functions and buttons to become familiar with.

Analog Oscilloscopes are generally less expensive than digital types, however, some of the major manufacturers, such as Tektronix and Keysight, do not make Analog Oscilloscopes any longer, so the oscilloscopes can only be purchased from other manufacturers or on the secondary market.

Digital Oscilloscopes

In a Digital Oscilloscope, the input signals are sampled, stored and then processed through an analog-to-digital converter that converts the measured signal into digital information before the signal is shown on the display.

This digital processing allows for wider measurement capabilities, more accurate measurement data, and a number of additional features and advanced signal analysis capabilities that are not possible with Analog Oscilloscopes.

The digital processing of the signals has led to an increase in ultra-high frequency capabilities. Bandwidths exceeding 1GHz are common with Digital Oscilloscopes. Digital Oscilloscopes are also able to trigger on a much wider variety of signals, such as transients or voltage spikes, to be able to troubleshoot problems quickly and easily.

Digital Oscilloscopes can measure all types of analog signals but are especially useful when working with digital or logic signals, such as with communication equipment or when measuring modulated waveforms. Digital Oscilloscopes provide a wide array of mathematical and statistical measurement functions. Many of the latest Digital Oscilloscopes have digital outputs that can be used in other data acquisition systems, computer software applications or sent to printers.

The displays on Digital Oscilloscopes use LCD technology which makes them resemble newer TVs or computer displays. The displays also do not require the circuitry or power requirements of the analog displays, which makes them much more energy-efficient. This makes Digital Oscilloscopes much smaller, lighter and more portable. Some Digital Oscilloscopes are even designed to run on battery power. The digital displays have a full spectrum of color options, which makes viewing the different input channel signals easier, which is especially useful on the 4 channel units.

Some Digital Oscilloscopes may feel overwhelming to use as they have many more features, menus and buttons to contend with, so there is a steeper learning curve in learning all of their capabilities.

Although Digital Oscilloscopes cost more than Analog Oscilloscopes, the prices for Digital Oscilloscopes have become reasonably priced, depending on the bandwidth required, especially with the influx of new manufacturers such as Rigol and GW Instek.

While there still may be some applications where using an Analog Oscilloscope is advantageous, today, Digital Oscilloscopes, and their advanced capabilities, represent the majority of new oscilloscopes purchased.

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