Thread Subject:

bode plots

I want to make a bode plot of some data but cannot seem to figure out how the make the function bode work if I'm only have the frequency, gain, and phase angles.


so far I have:

a = 2*28.04*.171; %numerator of transfer function
b = 28.04^2; %natural frequency
tf1 = tf(28.04^2,[1 a b]);
figure;
bode(tf1)

This gives me one of the bode plots.

I want a bode plot from this table:

freq gain phase
3.264 -7.19087236 47.0016
1.058 -10.28891155 15.2352
4.87 -10.25942729 129.7368
7.62 -18.84016106 205.74

Is making a bode plot from this raw data possible?

On 9/20/2011 8:00 PM, Chris wrote:
> I want to make a bode plot of some data but cannot seem to figure out
> how the make the function bode work if I'm only have the frequency,
> gain, and phase angles.
>
>
> so far I have:
>
> a = 2*28.04*.171; %numerator of transfer function
> b = 28.04^2; %natural frequency
> tf1 = tf(28.04^2,[1 a b]);
> figure;
> bode(tf1)
>
> This gives me one of the bode plots.
>
> I want a bode plot from this table:
>
> freq gain phase
> 3.264 -7.19087236 47.0016
> 1.058 -10.28891155 15.2352
> 4.87 -10.25942729 129.7368
> 7.62 -18.84016106 205.74
>
> Is making a bode plot from this raw data possible?

Since you already have the data, why don't you just use the semi log
option in the "plot" command and convert the gain units to dB and then
plot the data as two separate gain and phase plots?