Another example of a type 1 system is the open-loop transfer function:

as shown below:

**To generate the Nyquist
plot**

1.
Create the above diagram using a **const**, **transferFunction**, and
**plot** block.

2. Enter the following polynomial coefficients to the transferFunction block:

Numerator: 1

Denominator: 1 -1 0

**Note:** Always leave spaces
between coefficient values.

3.
Choose **System >** **Go**, or click in the toolbar to simulate the diagram.

4.
Select the **transferFunction** block.

5.
Choose **Analyze** **>** **Nyquist** **Response**.

6.
You are reminded that the system has poles on the imaginary axis, which will
result in Nyquist circles at infinity. Click **OK**, or press
**ENTER**.

7.
In the **Nyquist** dialog box, you have the option to change the maximum
frequency range. The default value is 10. Leave it unchanged and click
**OK**, or press **ENTER**.

8. The Nyquist plot appears.

9. Drag on its borders to adjust its size.

In this case, you can observe that the point (-1,0) is
enclosed by the Nyquist contour. Consequently N > 0. Moreover, since the
number of clockwise encirclements of the point (-1, 0) is one, N = 1. The poles
of *GH*(*s*) are at *s* = 0 and *s* = +1, with the second
pole appearing in the right-half plane. This implies that *P*, the number
of poles in the right-half plane, equals one.

In this case, N ≠ -*P*, which indicates that the
system is unstable.

The number of zeros of 1 + *GH*(*s*) in the
right-half plane is given by: