Can Asymptote Approximations Fully Construct a Bode Plot?

[Jimbo]

Hi

If you have asymptote approximations of a Bode plot - do you just find the vector sum of each asymptote to construct the 'full' bode plot?

I hope that makes sense

Any help much appreciated

Jimbo

 

[jamesrc]

I'm not quite sure what you mean. Are you talking about adding two Bode plots like when you have two transfer functions in series? Maybe you're breaking up the polynomial into its constituent parts; that's the same difference. When multiplying these terms together, the result is addition on the Bode plot. Say you have
$H(s) = \frac{K(s+1)}{s}$

You can break that up into an integrater (pole at the origin), a zero at s = -1, and a constant (gain) multiplier K. Draw the Bode plot for each component and sum together to find the overall Bode plot.

If you're talking about getting the actual Bode plot from the straight-line approximation, that's a different question. You can put in accuracy points to help you draw the curves or you could plot it exactly using something like MATLAB.

 

[ravenprp]

Hi Jimbo,

Constructing Bode diagrams involves plotting the magnitude and phase response of a system on a logarithmic scale. To answer your question, yes, you can find the vector sum of each asymptote to construct the full Bode plot. However, it is important to note that asymptotes are only approximations and may not give the exact response of the system. It is always recommended to also include the actual measured response of the system in the Bode plot.

In order to construct the full Bode plot, you can follow these steps:

1. Identify the transfer function of the system.
2. Convert the transfer function into a standard form (if it is not already in one).
3. Determine the break frequencies and the corresponding slopes of the transfer function.
4. Plot the asymptotes for the magnitude and phase response.
5. Plot the actual measured response of the system on the same graph.
6. Use a logarithmic scale for both the frequency and magnitude/phase axes.
7. Add labels and a legend to the graph for clarity.

I hope this helps. Good luck with your Bode diagrams!