Analog and digital signal

Both analog and digital signals are used to transmit information (through electric signal). First, the information is transformed into corresponding electric signal. In analog technology is translated into electric pulses of varying amplitude, while in digital technology into binary digits (zeros and ones) and each bit (binary digit) represents of two distinct amplitudes.

Comparison table

analog signaldigital signal
continuous, represents physical measurements discrete time, generated by digital modulation
continuous range of (analog) values discrete or discontinuos values
waveforms as they are samples analog waveforms into (limited set of) binary numbers

Conversion of analog signal into digital signal

1st analog signal


2nd sampling


3rd quantization


4th coding samples

000 001 010 011 100 101 110 111

5th digital signal

010 100 101 110 111 111 
111 111 111 110 101 101 

Digital signal consists of (quantized and coded) samples; in this case each sample is represented by 3 bits (binary digits).


Analog and digital signal

samples: 0122424
quantization levels: 08816
Analog signal:
1111 1110 1101 1100 1011 1010 1001 1000 0111 0110 0101 0100 0011 0010 0001 0000
Digital signal:
0000 0000 0101 1010 1011 1011 
1100 1100 1101 1110 1110 1111 
1111 1110 1110 1101 1100 1100 
1011 1011 1010 0101 0000 0000
111 110 101 100 011 010 001 000
Digital signal:
000 000 010 101 101 101 
101 110 110 110 111 111 
111 111 110 110 110 101 
101 101 101 010 000 000
111 110 101 100 011 010 001 000
Digital signal:
000 010 101 101 110 111 
111 110 110 101 101 000

Digital signal:
none