Digital vs. Analog Transmission

1. Noise Immunity: Digital signals are inherently less susceptible than analog signals to interference caused by noise because with digital signals it is not necessary to evaluate precise amplitude, frequency or phase. Instead pulses are evaluated during the precise time interval and simple determination is made whether the pulse is above or below a prescribed reference level. 

2. Multiplexing: Digital signals are better suited than analog signals for processing and combining using a technique multiplexing.

3. Easy to Store: It is simple to store digital signals than analog signals.

4. Resistant to additive Noise: Digital transmission systems are more resistant to analog system to additive noise because they use signal regeneration rather than signal amplification. Noise produced in electronic circuit is additive, therefore S/N ratio deteriorates each time an analog signal is amplified.

5. Used for Long Distance: Digital regenerators sample noisy signals and then reproduce an entirely new digital signal with same S/N ratio as the original transmitted signals. So digital transmitted signals can be transported longer distance than analog signals.

6. Transmission errors can be detected easily: The transmission errors can be detected and corrected more easily and accurately than is possible with analog signals.

Disadvantages of Digital Transmission

1. More Bandwidth Requirement: The transmission of digitally encoded original analog signal. BW is one of the important aspects of any communication system because it is costly and limited.

2. Extra Circuitry for encoding and Decoding: Analog signals must be converted to digital pulses prior to transmissions and converted back to their original analog form at receiver, thus require additional circuitry for encoding and decoding.

3. Require Synchronization: Digital transmissions require precise time synchronization between the clocks in transmitter and receiver.