What is a Digital Storage Oscilloscope?
A digital storage oscilloscope is an electronic test instrument which can store a digital copy of each waveform that it measures. It uses analog-to-digital converters to sample and digitize measured voltages, storing the results in memory. The stored waveforms can then be processed further using digital signal processing techniques. This type of oscilloscope is used by engineers, scientists and technicians to measure signals in electronic circuits. Many spectrum analyzers, medical devices and ignition analyzers also include a customized oscilloscope to measure and display data.
Oscilloscopes, also called scopes, can display changes in signal voltage over time. A modern scope usually has a rectangular screen which displays the input voltage on one axis over time on the other. A scope may also be able to display a second signal voltage instead of time on the other axis. Some can display a three-dimensional figure by using a third waveform to alter the intensity of the screen image. Other scopes can also display multiple waveforms at once, separately or superimposed on each other for comparison purposes.
Like other types of digital scopes, a digital storage oscilloscope converts analog input voltages into digital data. The maximum frequency it can measure is mainly determined by two factors. One is the nature of the signal amplifier and analog-to-digital converter on each input. The other is the sampling rate which the scope is capable of, often measured in millions or even billions of samples per second. When a signal is captured, as many samples as possible are stored in memory to represent the waveform.
Also known as a DSO, a digital storage oscilloscope can apply digital signal processing techniques to manipulate a waveform once it is captured. This processing can be done in the scope itself or with the aid of an attached computer. Since the waveform is stored digitally, it can be displayed for any length of time and recalled later when needed. In contrast, an analog storage scope can only maintain an image for a short period of time using a special display tube.
A digital phosphor scope is an advanced form of digital storage oscilloscope. It includes a parallel processor which is dedicated to waveform acquisition. Once a waveform is converted to digital form in a standard DSO, it takes a certain amount of time to process and store the digital signal information. During this time, the scope is unable to continue capturing an incoming signal since it is busy processing the first one. The second processor in a digital phosphor scope can capture a new signal while the first continues its work on the original signal.
A digital sampling scope is a digital storage oscilloscope which is designed to measure very high frequencies above one Gigahertz. The sampling rate of most scopes is not fast enough to capture signals at these frequencies. A digital sampling scope gets around this problem by collecting samples from several identical successive waveforms. From this information, it can process and assemble a complete picture of the actual waveform.
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