Difference between decimation and sample time

Hi all,

What's the difference between decimation and sample time in the scope of Simulink? And how do I determine which option to use under what circumstance?

Thanks edwin.

Answer 1

[Guy Rouleau]

Decimation: The scope will show only 1 point every X time steps. Whatever the rate of the input signal, with a decimation of 5, the scope will show you 1 point every 5 time steps.

Sample: You want a fixed rate. one point every 0.001sec or 1 point every 0.2 sec. In that case, even if the solver would not need to take a step at that time, it will take one to generate that point.

As you can guess, the difference is especially important if you use a variable sample time solver.

[Edwin Fonkwe]

Hi Guy. Thanks for this explanation. In my experience, the sample time gives me more accurate results with a value of 1e-7 than the decimation. With switching circuits, sometimes the difference is very very glaring. However, sample time slows down the simulation too.