Timebase

What it does

You can use the Timebase control to set your PicoScope’s timebase and gain access to the related set of sampling settings.

Your oscilloscope’s timebase sets the total duration of each of your displayed waveforms. It is expressed as time per division: As there are always ten time divisions across PicoScope’s graph views, the timebase is equal to the total waveform duration divided by ten. So, if a displayed waveform has a total duration of two seconds, the equivalent timebase setting is 200 ms per division.

You can think of your scope’s timebase as representing the speed with which your waveform fills the screen: a low timebase will cause your waveforms to fill your screen more quickly than a high timebase. For this reason, some people refer to timebases as being fast or slow.

How it can help you

An oscilloscope’s job is to show you how waveforms change with time. Some waveforms or waveform parts may change very quickly with time and others very slowly. You use the timebase control to change the capture duration to get the best view of the waveforms or waveform parts you want to examine.

For example, by reducing the timebase, you can view the details of a quickly changing waveform, such as an injection event or a signal packet of FlexRay network data. However, to capture a set of quickly changing waveforms in less detail or view a slowly changing waveform, increase the timebase. High timebases are particularly helpful when you want to capture lots of events over long periods to catch intermittent faults.

By default, PicoScope Automotive sets your timebase to 20 ms/div. With this timebase, your waveforms will have a total duration of 200 ms (0.2 seconds), which is ideal for capturing events occurring during an engine cycle when the engine is at idle; at idle one engine turn (half an engine cycle) takes around 1/800th of a minute, which is 1/800*60 = 75 ms (0.075 seconds) so two turns (the complete engine cycle) takes 150 ms (0.150 seconds).

Note that you must balance your chosen timebase against the total number of samples that make up your waveform, where the latter depends on the sample rate/sample interval. If your sample rate is too low, you won’t collect enough samples during your capture and will lose waveform detail. The sampling settings are available in the Sampling tab of the Timebase panel.

How to use it

Increase or decrease your PicoScope’s timebase respectively by clicking the + or - buttons on the Timebase control. Alternatively, click on the Timebase control to open the Timebase panel and click on a value to directly select an available timebase.