Synchronization of the sweep with the signal under study

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Standby scan mode

In the standby sweep mode, on the contrary, if there is no loan data or its level is insufficient (or if the synchronization mode is incorrectly configured), the sweep is absent and the screen goes dark. The sweep is started when the signal reaches a certain level configured by the operator, and it is possible to configure the sweep to be started both by the rising edge of the signal and by the falling edge. When studying pulse processes, even if they are non-periodic (for example, non-periodic, fairly rare shock excitation of an oscillatory circuit), the standby mode ensures visual immobility of the image on the screen.

In the standby mode, the sweep is often triggered not by the signal being studied itself, but by some synchronous signal, usually preceding the process being studied, for example, a signal from a pulse generator that excites the process in the circuit being studied. In this case, the triggering signal is fed to the auxiliary input of the oscilloscope - the sweep trigger input - the synchronization input.

One-time launch

In single mode, the sweep generator is "cocked" by an external action, for example, by pressing a button, and then waits for the start in the same way as in the standby mode. After the start, the sweep is performed only once; to start it again, the sweep generator must be "cocked" again. This mode is convenient for studying non-periodic processes, such as logical signals in digital circuits, so that subsequent sweep starts on signal edges do not "clutter" the screen.

The disadvantage of this scanning mode is that the luminous spot runs across the screen only once. This complicates observation during fast scanning, since the image brightness in this case is low. Usually, in such cases, screen photography is used. The need for photographing on film was previously eliminated by using oscilloscope tubes with image storage; in modern digital oscilloscopes, the process is stored in digital form in the digital memory (RAM) of the oscilloscope.