# Help and Documentation

How to run time-domain analysis

Time domain is a term used to describe the analysis of signals with respect to time. In the time domain, the signal or function's value is known for all real numbers, for the case of continuous time, or at various separate instants in the case of discrete time.

An oscilloscope is a tool commonly used to visualize real-world signals in the time domain. A time-domain graph shows how a signal changes with time.

Click on Run menu and select Time Domain Analysis or use shortcut key t.

What is Analysis Time?

Analysis Time is unit of time for which the user intends to run the simulation

What is Sampling Time?

Sampling Time is the time between two successive samples

Number of Samples:

You will get the number of samples by dividing analysis time by sampling time

In the above case, it is 100ms/100us = 1000

How to choose Analysis time?

If you have single signal source in your circuit;

Calculate the time period of the signal, multiply it by 5. This will be your analysis time.

For example, If you have a signal sources of 100Hz

1/100Hz = 10msec; 10msec x 5 = 50msec

How to choose sampling time?

For the calculated value of analysis time try to maintain number of samples as 1000

In the above case, sampling time is 50msec/1000 = 50usec

How to choose Analysis and Sampling time when I have multiple signal sources in the circuit?

Consider the lowest frequency signal source in your circuit, calculate the time period, multiply it by 5. This will be your analysis time.

For example, If you have two signal sources of 100Hz and 10KHz

1/100Hz = 10msec; 10msec x 5 = 50msec

Consider the highest frequency signal source in your circuit, calculate the time period, divide it by 10. This will be your sampling time.

For example, If you have two signal sources of 100Hz and 10KHz

1/ 10KHz = 100usec; 100usec/10 =10usec

Few things to remember:

It is very important to choose the right sampling time. If number of samples are very less the output you get on the plotter or oscilloscope may not be accurate. At the same time if the number of samples is large the simulation tends to become slower.