With analog scopes life was simple: you just selected the bandwidth that you required. On some scopes, the quoted bandwidth is not available on all voltage ranges, so check the data sheet carefully. Unfortunately, high-bandwidth scopes are expensive, so you may have to compromise here. As a rule of thumb, try to purchase a scope with a bandwidth five times higher than the maximum frequency signal you wish to measure. For example, a 20 MHz pure square wave viewed on a 20 MHz bandwidth scope will be displayed as an attenuated and distorted waveform. Remember also that, if your input signal is not a pure sine wave, it will contain higher-frequency harmonics. Or, to put it another way, they allow the displayed trace to be 29% in error of the input before calling it a day. It is worth noting that most scope manufacturers define the bandwidth as the frequency at which a sine wave input signal will be attenuated to 71% of its true amplitude (–3 dB point). However, since a DSO is composed of amplifiers, attenuators, ADCs, interconnects, and relays, MFED response is a goal that can only be approached, never met completely. A frequency response of this type delivers excellent pulse fidelity with minimum overshoot, undershoot and ringing. This response is known as the Maximally Flat Envelope Delay (MFED). The goal of scope manufacturers is to achieve a specific type of frequency response with their designs. It therefore follows that the analog bandwidth of your scope must be higher than the maximum frequency that you wish to measure (real-time).īandwidth alone is not enough to ensure that a DSO can accurately capture a high-frequency signal. This can be defined as the maximum frequency of signal that can pass through the front-end amplifiers. The first feature to consider is bandwidth. In addition, the DSO is often used as the front end of a high-speed data acquisition system, making the cost per channel much more economically viable.
Signalscope tutorial Pc#
Modern DSOs, with their PC connectivity, can also be fully integrated into Automatic Test Equipment (ATE) systems. There are other criteria that have added weight to the analog vs digital debate. Only a few manufacturers still make analog scopes some of the models still on sale are based on rather old technology and often have very limited performance.īuying a second-hand analog scope may initially seem like good economic sense but, before doing so, check for the availability of spares, as high repair costs can make the purchase a false economy. If you are still tempted by an analog scope you will find your choice limited. In fact, many people purchasing oscilloscopes today are replacing analog with digital.Īlthough there are still some engineers who love the look and feel (let alone the warmth) of analog scopes, they have few, if any, features that cannot be surpassed by a DSO. Most electronics engineers will have used an analog scope at some time and will be familiar with its layout and operation. Before describing what to look for in an digital oscilloscope, it is necessary to begin by at least touching on analog. The focus of this article is on Digital Storage Oscilloscopes (DSOs) as they represent the majority of new oscilloscopes purchased today.
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