One of the main functions of an oscilloscope is acquisition of the analog signal; that signal is then passed on to an analog to digital converter where the signal is digitized. Once it is digitized, that information has to be stored in memory, processed and plotted / displayed. The oscilloscope memory is directly tied to the sample rate. The more memory you have, the higher you can keep the oscilloscope’s sample rate as you capture a longer period of time. The higher the sample rate, the higher the effective bandwidth of the oscilloscope. But when bigger is not always better. Deep memory is clearly beneficial when it comes to sample rate, but when would it not be advantageous? Deep memory puts a larger strain on the system. Some scopes are setup to handle that well and remain responsive with a fast update rate; others attempt to make it a banner specification when it isn’t really usable and slows the update rate by orders of magnitude.
Sources: www.tmworld.com, www.agilent.com
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