Understanding the Bode Plot: Frequency vs. dB

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Discussion Overview

The discussion revolves around the characteristics and conventions of Bode plots, specifically addressing the axes used in the plots and related queries about plotting in MATLAB. The scope includes theoretical understanding and practical application in control systems.

Discussion Character

  • Exploratory, Technical explanation, Homework-related

Main Points Raised

  • One participant questions whether the x-axis of a Bode plot should represent angular frequency (omega) or frequency (f), noting that the y-axis is in dB.
  • Another participant states that they typically use angular frequency (in radians per second) on the x-axis of their Bode plots, with the y-axis representing 20 log(|H(jw)|) in dB.
  • A different participant seeks assistance on setting the axis range for a Nyquist plot in MATLAB, providing a specific example of a transfer function.
  • A response emphasizes the importance of starting a new thread for unrelated questions, referencing a previous thread for additional context.
  • A later reply acknowledges the previous comment about thread etiquette.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the x-axis representation for Bode plots, as different conventions are mentioned. The discussion about MATLAB plotting remains unresolved, with no clear agreement on the best approach.

Contextual Notes

There are limitations regarding the assumptions made about the conventions of Bode plots and the specific requirements for MATLAB plotting, which are not fully explored in the discussion.

Who May Find This Useful

Individuals interested in control systems, signal processing, or those looking for guidance on plotting techniques in MATLAB may find this discussion relevant.

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Is the x-axis of a Bode plot supposed to be angular frequency omega or just the frequency f? The y-axis is in dB. Thanks!
 
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Usually when I draw it on paper, I have it in angular frequency [rads/sec] (log scaled). The y-axis is 20 log (|H(jw)|) [dB].
 
hi, i would like know how to set the range on the axis? for an example i want to plot a nyquist plot with the range of x-axis is from -0.08 to 0.02 and the range of y-axis is from -0.2 to 0.2. (with the system G =(5s + 200)/((s)*(s^2 +4s + 10)*(s^2 + 10s + 150))...

please help me out here if anyone knows how to write in the m.file(MATLAB)...thanks
 
Welcome to PhysicsForums! For future reference, whenever you have something like this (a somewhat related question that nevertheless does not directly follow from the previous items) you really ought to start a new thread, not resurrect one that's 4 years old!

In any case, take a look in this thread:
https://www.physicsforums.com/showthread.php?t=303967

(Second mention in less than 3 hours!)
 
sorry about that :)
 

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