There are four basic types of sweeps:
(a) Free Running or Recurrent Sweep: in the free running or recurrent sweep, the sawtooth waveform is repetitive. A new sweep is started immediately after the previous sweep is terminated and the circuit is not initiated by any external signal.
(b) Triggered Sweep: A waveform to be observed on the CRO may not be periodic by may perhaps occur at irregular intervals. In this case, it is desirable that the sweep circuit remain in-operative and the sweep be initiated by the waveform under examination under examination. In some cases the waveform may be periodic, but it may be that the interesting part of the waveform is of a very short duration compared to the period of the waveform. Under such cases a triggered sweep is used. In triggered sweep or single sweep, the spot is swept once across the screen in response to a trigger signal. The triggered sweep is used for examination of transients or one time signals and the waveform is photographed for record. The trigger can be obtained from the signal under investigation or by an external source.
(c) Driven Sweep: In most cases, a driven sweep is used where the sweep is recurrent but trigged by the signal under test.
(d) Non saw-tooth Sweep: for some application like comparison of two frequencies or for finding phase shift between two voltages, non sawtooth sweep voltages are utilized for the sweep circuit. Sweep frequencies vary with the type of oscilloscope. A laboratory oscilloscope may have sweep frequency upto several MHz. A simple oscilloscope for audio work has an upper limit of 100 kHz. Most TV services require a sweep voltage frequency upto 1 MHz.