Signal Types
Snapshot of the front panel of the simulator:
When you are to analyze dynamic systems (e.g. control systems, motors,
thermal processes, signal filters), you may excite the system with some
signal.
This simulator realizes the most common test signals:
- Square pulse, which is an appoximation to an impulse
- Step, which is the most commonly used signal
- Ramp
- Sinusoid, which is used in frequency response analysis
In practice the test signal is overlayed (added to) a constant, which
is denoted bias or DC component (direct current).
- Square pulse: Ideally an impulse
is a signal of infinite amplitude and zero duration but with a finite
area men A under the signal curve. The area is also denoted the strength
of the impulse. If we assume that the impulse comes at time t_{0}
and that it has bias B, it can be expressed as follows:
y(t) = Ad(t - t_{0}) + B
An ideal impulse can not be realized fully. An approximation is a square
pulse having amplitude
or height H and duration dt. The area of this signal is A = H*dt.
Task:
Run the simulator. Select signal type "Square pulse". Observe
how the signal depends on H, dt, and B, and time t_{0}.
- Step: A step is given by
y(t) = US(t - t_{0}) + B
where U is the step amplitude or step height, and B
is the bias. t_{0} is the step time. S(t) is the unit step
function, having amplitude 1.
Task:
Select signal type "Step". Observe how the signal depends on U,
B and t_{0}.
- Ramp: A ramp is given by
y(t) = KR(t - t_{0}) + B
where K is the slope. B is the bias. t_{0} is the starting time. R(t)
is a unit ramp, having slope 1, and starting at t = 0.
Task:
Select signal type "Ramp". Observe the signal depends on K,
B and t_{0}.
- Sinusoid: A sinusoid is
given by
y(t) = Asin(wt) = Asin(2p f t) + B where A is
the amplitude, w is the frequency in rad/s, f is the frequency in Hertz
and B is the bias. The period of the signal is
T_{p} = 1/f [sec]
Task:
Select signal type "Sinus".
- Observe how the signal
depends on
A, f and B.
- Select one specific f
value, and verify that the period actually is 1/f.
[SimView] [TechTeach]
Updated 21. January 2008.
Developed by
Finn Haugen.
E-mail: finn@techteach.no. |