Digital storage oscilloscope
A digital storage oscilloscope (DSO) is an oscilloscope which stores and analyses the input signal digitally rather than using analog techniques. It is now the most common type of oscilloscope in use because of the advanced trigger, storage, display and measurement features which it typically provides. The input analogue signal is sampled and then converted into a digital record of the amplitude of the signal at each sample time. The sampling frequency should be not less than the Nyquist rate to avoid aliasing. These digital values are then turned back into an analogue signal for display on a cathode ray tube (CRT), or transformed as needed for the various possible types of output—liquid crystal display, chart recorder, plotter or network interface. Digital storage oscilloscope costs vary widely; bench-top self-contained instruments (complete with displays) start at US$300 or even less, with high-performance models selling for tens of thousands of dollars. Small, pocket-size models, limited in function, may retail for as little as US$50. (Wikipedia).
