Noise cannot be eliminated in an analog signal because the analog signals are susceptible to physical interference. Noise can be removed from digital signals because the signal is converted to binary values (0’s and 1’s) before it is converted back to sound, making it much easier to control noise and interference in the signal. Analog signals are measured and transmitted based on the measurements, and since the signals can only be measured so often, there is only so much that can be done to eliminate noise. An example of this would be someone speaking into a microphone in a crowded room. The noise from the background would also be amplified into the microphone and the sound that came out would be much less clear than just the single person’s voice.
Morse code is an example of noise removal in a digital signal because it uses simple characters that can be translated easily into sound and uses spaces in time in between sounds so that the listener can distinguish between the sound of each symbol before translating it back into that symbol. This is similar to how a digital signal is converted from a sound to binary code, then back to a sound for the listener to interpret.
