# What is Bode: Definition and 103 Discussions

Böde is a village in Zala County, in Hungary. In its vicinity can be found the church of Böde-Zalaszentmihályfa from the Árpád dynasty age.

View More On Wikipedia.org
1. ### Where is the 'Origin' on a Bode Plot?

Wasn't sure where exactly to post this. It isn't a homework problem. I am studying for my Fundamentals of Engineering exam and am struggling with control system problems. Can someone tell me where exactly the origin is on a Bode Plot? I understand the general concept of poles and zeroes but I...
2. ### Engineering How do I draw the Bode diagram of this transfer function?

Hello! I have this filter here a) Calculate the transfer function T(Ω) = Ua/Ue using voltage dividers.For this, use the normalized angular frequency Ω = ωRC and bring the result into the form ##T(Ω) = \frac{A+jB}{C+jD} ## . The result must not contain any double fractions. I was able to that...
3. ### Inverting op amp frequency response Bode plot help

Using analog discovery 2 kit and the bode plot produced by the network analyzer is off. The scope looks fine and everything is behaving how it should except for the bode plot. The magnitude of the bode plot will start at the correct dB then right before tapering off it shoots up a few dB and...

5. ### Engineering W0 = 1/RC? Transfer Functions and Bode Plots

Here is the example and solution in full. I have circled where I'm at and highlighted the part that's tripping me up. I managed to get... and getting everything in terms of the angular frequency seems to be critical for getting the plots for the Frequency Response. I checked my notes on RC...
6. ### Engineering Bode plot for active low pass filters

Hi Can anyone help with this? I understand what the bode plots should look like but I am not sure how to produce a plot in excel for them without any values The transfer functions are: Vout/Vin = 1/(SQRT(1+(ω/ωc)^2) and Vout/Vin = -G/(1+j(ω/ωc)) As both are first order filters they will have...
7. ### Scalar in terms of multiple variables, Nyquist & Bode Plot

Homework Statement A scalar is given by It is controlled by With step time h = 0.2 s 1. Find the discrete equivalent model 2. Check the stability of closed loop (K = +1) 3. Obtain the via the Bode plot Homework EquationsThe Attempt at a Solution So for question 1. This is where I'm...
8. ### How Do Bode Plots Help in Designing Controllers for Liquid Level Management?

Homework Statement This is the second part my problem. In the first part the Open Loop and Closed loop TF where worked out from design parameters. In later questions a lead or lag commentator is needs to be designed. Design an appropriate controller to ensure the steady state error in the...
9. ### Bode phase plots and initial angles of transfer functions

Hello everyone. So I have a test coming up and I am struggling with the concept of figure out what the initial phase or angle of a transfer function is. For instance, consider the following transfer function: L(s) = 4/s(.4s+1)(s+2) So the initial angle for L(s) is -90 degrees. Is there a...
10. ### Asymptotic magnitude Bode plot for a network function

Homework Statement I am working on the following problem: The Attempt at a Solution I have the solutions, I just don't understand: I know that the pole should be the root of the denominator? but in all the examples I was given they used s and not jw, so what is the variable in the network...
11. ### How transfer functions become Bode plots

Homework Statement I have a question related to taking the logs of transfer functions, getting the individual Bode plots of each subsequent factor, and adding those plots graphically. I'm working from Fundamentals of Electric Circuits, 5th edt. Let me start with the following screen capture...
12. ### How can i read this Bode plot?

I think that first peak of the graph represent a resonance frequeny but i don`t know some peaks which are located after first peak. Is it a just noise? or some other?
13. ### Bode Plot Application: Increase Frequency Response & Magnitude Understanding

Hello, After long time i am able to find Laplace transform function but can't understand the bode plot which give information of frequency response and magnitude i think plaese anyway here how can push my thinking ahead in it?
14. ### Bode Plot Notation: Gain & Phase Margins Explained

Hi, i was just wondering if someone would be able to tell me what ωπ means when finding the gain and phase margins on a bode plot?
15. ### Bode Plot Method For a Transfer Function

Hi , I was hoping you could look at this link and let me know if I have interpreted the method correctly http://i.imgur.com/5axTiBN.jpg As I understand it the transfer function has had s replaced by jw but also the top and bottom are divided by 10 - This is so that the brackets on the bottom...
16. ### How do you do a Bode plot comparison with LTSpice?

I'm trying to use LTSpice in order to fine tune LC circuits, but a road block I've hit is that when I run the simulation and generate a bode plot, the previous plot is overwritten, so I can't visually compare the effects of the L C changes. Some graphing programs have a function that let's you...
17. ### Bode Plots & High Pass, Low Pass, Band Stop and Pass Frequen

Homework Statement Hi, I just need some confirmation on 3 questions H(s) = 1/(s+1)^2 1. I was asked to calculate the poles and zeros. I believe zeros: none poles: 2 (or p1,2) = -1 2. I was also asked to calculate the slope of the magnitude response was w -> 0 Here is my sketched graph...
18. A

### Identifying type of feedback by looking at bode plot

Homework Statement Below is the bode plot of return difference, 1+C(S)P(S) in a feedback system. Identify the frequencies where the feedback is large, negative, positive and negligible. P(S) = \frac{100}{s^2+2s+1} C(S) = \frac{220(s+50)}{s+200} Homework Equations Bode Plot, Feedback The...
19. ### Plotting Bode of Resistor w/ DC Source: 20*log(0)

I am ploting bode of resistor connected with DC source.So no freqvancy at all! The bode magnitude plot should be(or it should start from) 20*log(jw)=20*log(0) (jw=0 because we have dc source) what should be the value??for step of 5v... what should bode look like??
20. ### Stability of a System: Bode Diagram Analysis

Hi, Is this Bode diagram tells that the system is stable? As I see it is, because of the φ>0. What doest it mean that the upper diagram has two zero-crossing?
21. ### Bode plot and stability margins

Homework Statement Homework EquationsThe Attempt at a Solution Hello, In part (b), I found ##k_{cu} = 0.5##. I found in part (d) a controller gain of ##k_{c} = -0.3## yielded a diverging output. Here are the bode plots for parts (a),(c), and (d). I don't understand how I should use the...
22. ### Bode plot for first order high pass (RL) - reality vs theory

Hey there! So I have this circuit: with R= 1kOhm and L=10mH and for some reason the theoretical and real values differ drasticly for lower frequencies Brown lines are representing the asymptotic and approximation lines. Blue lines are connecting my measured values. Amplitude is the amplitude...
23. ### Sketch Bode Plot for \$\frac{0.5}{1 - \frac{3145j}{w}}

Homework Statement \frac{0.5}{1 - \frac{3145j}{w}} , sketch the bode plot Homework EquationsThe Attempt at a Solution Moving the jw to the bottom \frac{0.5}{1+ \frac{3145}{jw}} Let s = jw \frac{0.5}{1+ \frac{3145}{s}} = \frac{0.5}{\frac{s+3145}{s}} = (0.5) \frac{s}{s+3145} =...
24. ### Extracting information from a Bode Plot (PM, GM, etc...)

Hi all, 1. Homework Statement http://imgur.com/kqZK1Vv This is the loop gain (A.F.) of unity feedback system. I need to extract DC Gain Bandwidth GBW (is GBW Gain Bandwith ?) f unity (I suppose this is unity frequency) Phase Margin Gain Margin What is the optimal PM and f2/GBW for time and...
25. ### Sampling Time Calculation for Bode Plots: Plant Comparison & ZOH Preceding

Homework Statement In the figure, the Bode plots of a continuous-time plant (thin line) and of its discrete-time counterpart, representing the discrete-time operation of the plant preceded by a Zero Order Hold (ZOH) (bold line), are displayed. What is the Sampling time used? Homework...
26. ### How to Draw a Bode Plot from a Given Transfer Function with a Zero at s=1

Homework Statement Hi, I'm given a transfer function, and am suppose to draw Bode plot from it. H(s) = ( 2000s (s - 1) ) / (s + 2000)^2 I'm wondering what to do for the zero at s = 1? Should I just solve this normally, as every example we have done and every example I've seen uses simple...
27. ### Controller Design with Bode Plots

I have two questions. One theoretical, and one pertaining to the homework question below. The theoretical question for which I am having trouble. When designing a controller to compensate a process using Bode Plots, why does my book seem to just use the forward loop gain rather than the...
28. ### Engineering Creating a Bode Plot for a Series RC High Pass Filter

Homework Statement Make a blode plot of a series RC high pass filter (log(gain) vs. f)... Homework Equations log(Gain)=log(Vout/Vin) I'm pretty sure the "Gain" is just the transfer function, for a highpass it should be the V_in = Vsupply, and V_out = V_capacitor. The Attempt at a Solution I...
29. ### Transfer function and Bode plot

Homework Statement Find the transfer function for the filter on the attached picture and sketch it in Bode diagram, if you know ##Q_0 =\frac{\omega _0L}{R}>>1## and ##\omega _0^2=\frac{1}{LC}##. Homework EquationsThe Attempt at a Solution If I am not mistaken, we defined the transfer...
30. ### Bode Plot Matlab Homework: High Pass Filter

Homework Statement I'm trying to make a theoretical Bode plot of a High pass filter (made up of a capacitor and a resistor). The transfer function is: ##T=\frac{V_{out}}{V_{in}}= \frac{R}{R+1/(j\omega C)} = \frac{1}{1-j\omega_0 / \omega}## With a corner frequency of 5 kHz or in...
31. ### Solving Bode Plot Questions: Finding the Gain for Accurate Magnitude Response

Hello, I have the following problem ( which should be uploaded below the text ) I've done part a) correct, I know how to sketch the bode plots but don't know how to find the gain in order to draw correct magnitute response bode plot. This is where I am stucked and if I find out how to find...
32. ### What is the significance of using a log scale in bode plots?

How did they get the blue box? I know where they got the 0.5 inside the brackets from but not sure about the rest. The bode plot in my data book has log10(wt) as the x-axis..
33. ### Understanding Bode Plots for Second Order Systems with ς‚= 0

hey guys, i have a question regarding bode plot g(s)= 1/(s2+4) i did get the magnitude plot correct but i am unable to understand the phase plot. by calculating on paper i got 0° but in MATLAB it changes from -360° to -180° i haven't understood how the initial phase is -360 which...
34. ### MATLAB I need Matlab help comparing bode plots neatly

This definitely isn't a homework question as the work is already done, I'm just trying to make my presentation neater for some reports I'm turning in. I am comparing theoretical data collected from a filter, to the actual data collected. I want to overlay the two to make the comparison. I am...
35. ### Bode plot with given transfer function

Homework Statement Homework Equations The Attempt at a Solution Hello, I am having serious problems being able to draw bode plots. At first the professor said to put everything into standard form with an (ω/ω_c)...and then there is also a table in the textbook with standard forms that don't...
36. ### What is the Frequency for Unity Loop Gain in Low-Pass Amplifier with Feedback?

Homework Statement I need some help with the following problem (it is from an old test paper). Below is the Bode plot of the open loop gain of an amplifier: A constant fraction β=0.1 of the output is fed back to the input. This feedback does not load the amplifier. Using the Bode plot...
37. ### Bode Plots & Frequency in Control Systems: Demystified

What frequency are they referring to when they plot magnitude versus frequency in a bode plot of a control system? I don't understand where frequency comes from in control systems. I've researched this and I'm still very confused by what is meant by frequency.
38. ### Analysing bode plots. Stability

Hi all, I would be greatful is someone could kindly enlighten me as to the correct interpretation of the appended bode plots. My understanding when interpreting bode plots is that we desire 0 gain where the phase is equal to or exceeds 180 degrees (marginally stable / unstable). In...
39. ### Solving the Question: Bode Plot and Equation Example for Homework

Bode Plot It's The biggest one in the entire universe! Homework Statement The question is stated at the top of the image below. Did I answer the TWO questions with this image? https://fbcdn-sphotos-c-a.akamaihd.net/hphotos-ak-frc3/t1/1891009_10151901549150919_346181425_n.jpg...
40. ### MHB Constructing Bode Plots for $$H(s) = \frac{s}{s + 2}$$

I am trying to construct the Bode plots for $$H(s) = \frac{s}{s + 2}$$. For the magnitude Bode plot, $$H(i\omega) = \frac{1}{1 - i\frac{2}{\omega}}$$ and the decibel gain expression is $A_{\text{vdB}} = -10\log\bigg(1 + \frac{4}{\omega^2}\bigg).$ So this plots the first Bode plot, but I am...
41. ### Bode Plots in RL and RC circuits

Hey PF! I have a test tomorrow and some of the material is on the basics of RL and RC circuits set up as high pass or low pass filters. Does a High pass filter bode plot look the same whether it's RC and RL? Same with a low pass? Can anybody to an online resource of what bode plots look like...
42. ### Understanding the Relationship Between Poles, Zeros, and Bode Plots

Hello all. I have two questions. 1] How do poles and zeros relate to bode plots? What happens at a pole or zero? 2] Can you come up with a rough sketch of a bode plot if you know the following (without having to use the transfer function)?: - Zeros - Poles...
43. ### About bode plot horizontal axis question

I have a question I'm wondering in bode plot we write the horizontal axis w rad/sec what does this mean? is it normal scale 0.1 0.2 0.3 ... etc with equal distances?? it's clear not because it's drwan on semilog paper if it's the horizontal log w why then we write 0.1 ,0.2 ,,1 ...
44. ### Solving for Bode Critical Frequency: Guide and Equation Explanation

I am given a bode plot and have to label the cutoff frequency on there. G(jw)=2/(-w^2 +162jw +320) I got this equation where w is the critical frequency: 70922=81^2 + (170 -(w^2/4)) I am sure that this is wrong since I get the sqrt of a negative number for w. It would be really great...
45. ### How Do You Determine the Critical Frequency in a Bode Plot Equation?

Given an equation like 2/((jw)^2 +54jw +44), how would you find the critical frequency? I am getting a umaginary number and I am sure this is not true, please help!
46. ### Trouble interpreting Bode diagrams

Trying to get my head around frequency response and Bode plots, but I'm having trouble interpreting what's going on. The bode plot of a function is expressing what would happen to my function if I multiply it with sin(ωt), right? To get a better feel for it, I asked Matlab to give me the Bode...
47. ### How Do You Draw a Bode Plot for a Given Transfer Function?

Homework Statement Given this function in an open loop control system http://img255.imageshack.us/img255/3686/700qa.jpg Draw a bode plot of the transfer function: The upper graph will present the lines for each of the amplification factors for each of the system components, the lower...
48. ### Engineering Understanding Circuit Analysis from a Bode Plot

Homework Statement http://www.wifstrand.se/Albert/stuff/p13.3-6.png Homework Equations From circuit analysis I've found the network function to be H(ω) = -(10^(-4) +jωC1)/(1/R2 + jωC2) (could be wrong) The Attempt at a Solution I don't know how to determine the network...
49. ### Calculating Transfer Function off Bode Plot?

Hey guys. I was wondering if anyone could give me some hints or help me understand well how to get transfer functions off bode plots. Here is an example I need to solve: http://i1226.photobucket.com/albums/ee410/jean28x/bodeplotcalc.jpg
50. ### How do I see the gain from this Bode plot? (simple)

This is the Bode plot of a Broadband Bandreject Op Amp amplifier. The exercise says this: I know that in order to get both cutoff frequencies I need to subtract 3 dB from the plot, but how do I get the gain? I would think that the gain is 3 dB because it is also the distance between the top of...