Digital electronics course neso academy

 What is a signal?

F(x) for distance 

Or F(t)  for time is a signal.

A signal is a function that represents the variation for physical quantity with respect to any parameter.

F(x) = ax^2 - b^x +c

For example.

Straight line, parabola, etc.

 Y = mx + c 

Is also a function. 

Analog vs digital signal 

Consider the digital clock and analog clock. Consider the minute hand of analog clock.

Digital means it has certain levels. Nothing can be between two levels.

Analog means it can take any value. 

Discrete time signal- The signal defined for discrete intervals of time.

Discrete time signal is a subset of analog signal

Discreet signal
.

Time can take only discreet intervals but f(t) can take up any value. 

Analog signal

Both time and function of time can take up any value.

But, in digital signals, we make both time and f(t) discreet.

Digital signal 

Both t and f(t) have discreet values.

If we choose large discrete intervals for f(t) then we will have a large error.

For example, 

Case 1

F(t) = 0, 5, 10, 15, 20, 25, etc 

Has large intervals as compared to

Case 2

F(t) = 0, 2.5, 5, 7.5, 10, 12.5, 15, etc.

So, if we have an analog signal f(t1) = 7 ,

Case 1 gives

 

F(t1) = 5 

Case 2 gives

F(t1) = 7.5, which is more accurate. 

Need for digital signals

All real life signals are analog signals.

Digital signals help to reduce noise. Hence, they are used for communication. Special devices are used to convert analog signals into digital signals.