Thread Subject:

Nyquist plot

In control system engeneering, I would like to plot the Nyquist chart
of an analogue active filter that I have simulate on an electronic
software.
This software give me the data of gain and phase (bode plot) of my
filter and I would like to use MatLAB to plot the Nyquist diagram
with this Data. How can I do that ??
I have any Transfert function of the filter.

NeB,

Homework?

If you have the transfer function of the filter, use "nyquist".
If you have gain and phase data, use "polar".

Joerg

Thks
It's for my final year project of my degree !!
But when I plot a polar graph with theta my phase angle in radians
and rho the magnitude I don't obtain a graph who look like to a
Nyquist plot.
I need to perform in this way but if anyone have already do that I'm
interesting.

Hello I have the same issue. I have Bode plot data from an instrument that I would like to turn into bode plots and nqyuist plots in matlab. Is there a way to turn my Bode data into a continuous transfer function? Or is there a way to make a Nyuist plot directly from my data?


NeB <nebsound@hotmail.com> wrote in message <ef2c4b2.1@webx.raydaftYaTP>...
> Thks
> It's for my final year project of my degree !!
> But when I plot a polar graph with theta my phase angle in radians
> and rho the magnitude I don't obtain a graph who look like to a
> Nyquist plot.
> I need to perform in this way but if anyone have already do that I'm
> interesting.

You can take your frequency response data and create an FRD object (SYS =
frd(RESPONSE,FREQS)). You can then use commands such as bode(SYS) and
nyquist(SYS) to plot your data.

"tim " <tababich@gmail.com> wrote in message
news:k0m2n6$7dp$1@newscl01ah.mathworks.com...
> Hello I have the same issue. I have Bode plot data from an instrument
> that I would like to turn into bode plots and nqyuist plots in matlab. Is
> there a way to turn my Bode data into a continuous transfer function? Or
> is there a way to make a Nyuist plot directly from my data?
>
>
> NeB <nebsound@hotmail.com> wrote in message
> <ef2c4b2.1@webx.raydaftYaTP>...
>> Thks
>> It's for my final year project of my degree !!
>> But when I plot a polar graph with theta my phase angle in radians
>> and rho the magnitude I don't obtain a graph who look like to a
>> Nyquist plot.
>> I need to perform in this way but if anyone have already do that I'm
>> interesting.