| Customer
support |
|
| High
freq. signals are not simulating correctly |
|
| Whenever you are attempting to simulate high
frequency signals (for example a 100Hz or faster oscillator),
it is important that you adjust the simulation's timing
settings to maintain simulation accuracy. |
|
| Users need to tailor the simulation parameters
to their own particular circuits. Changes to timing settings
are required because PCs are often not able to keep up with
the high frequency signal
in real time resulting in eratic simulations or strange outputs
on a graph. |
|
| Please note that all circuits must be correctly
grounded (or earthed) before they can be accurately simulated.
A circuit
that is not properly grounded may still produce unexpected results. |
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| Understanding
simulation time |
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| The speed at which a circuit simulates is determined
by something called simulation time. |
| |
| Normally, simulation time is set to correspond
to real time, whereby one second of simulation time takes one
second to simulate. By slowing down simulation time, however,
you can investigate circuits that normally operate too fast
to be seen. Slowing down the simulation will also allow you
to generate more accurate results by simulating more time points. |
| |
| Adjusting a simulation's
timing |
|
| You can slow down the simulation
so that the high frequency signal can simulated more accurately.
This is done via Timing Control: |
|
 |
To change the timing settings
in Circuit
Wizard,
select Timing
Control... from the Project | Simulation menu. |
|
 |
To change the timing settings in Livewire,
select Timing
Control... from the Tools | Simulation menu. |
|
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| In the window that appears, the Time
Base setting
controls simulation time. It defines how much simulation time
takes
place in one second.
For real time operation, set the time base to 1 second. |
|
| Setting the time base to 500ms will mean that
the circuit simulates at half the speed, so it would take two
seconds to simulate one second of your circuit. |
|
| You should experiment with the Time
Base setting,
using the examples below as a starting point: |
|
 For
a signal of 100Hz, try a Time
Base setting
of 50ms. |
|
| For
a signal of 1kHz, try a Time Base setting
of 5ms. |
|
| For
a signal of 10kHz, try a Time Base setting
of 500us. |
|
| For
a signal of 100kHz, try a Time Base setting
of 50us. |
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| For more information on this topic,
click on the Help button
in the Timing Control window. |
| |
