The advantage of the analog storage oscilloscope is that it has higher bandwidth and writing speed than a digital oscilloscope, being capable of operating speeds of about 15 GHz. The digital oscilloscope as primarily limited in speed by the digitizing capability of the analog to digital converter. Aliasing effects also limit the useful storage bandwidth (Usb) of the oscilloscope to a value given by the ratio.
The value of constant C is dependent on the interpolation method used between the dots. For a dot display C should be about 10 and for sinusoidal interpolation C should be about 2.5.
The digital storage oscilloscope has a CRT which is much cheaper than an analog storage oscilloscope making replacements more economical. The digital oscilloscope is also capable of an infinite storage time, using its digital memory. Furthermore it can operate with a constant CRT refresh time, so giving a bright image even at very fast signal speeds. The digital storage oscilloscope is not however, capable of functioning in a variable persistence storage mode.
The time base in a digital oscilloscope is generated by a crystal clock, so that it is more accurate and stable than an analog oscilloscope, where the time base is generated by a ramp circuit. The analog to digital converter used in a digital oscilloscope also gives it higher resolution than an analog oscilloscope. For example, a twelve bit digitizer can resolve one part in 4096. A conventional analog oscilloscope typically resolves to about 1 mm on the screen that is to about one part in 50 equivalents to 6 bit resolution.
Digital storage oscilloscopes are also capable of operating in a look back mode, as described for waveform recorder. An analog oscilloscope collect data after it has been triggered. A digital storage oscilloscope is always collecting data and the trigger tells it when to stop. The oscilloscope can stop immediately on trigger. So that all the stored information is pre trigger or it can stop sometime after it has received trigger. If the delay is longer than longer than the storage capability of oscilloscope, then all the storage capability of the oscilloscope, then all the stored information is post trigger, as for an analog oscilloscope. The digital oscilloscope is also able to operate in a baby sitting mode. When the scope is trigged it prints out the stored results on to a hard copy recorder (or disc storage) and then rearms itself ready for another reading.