# Analog vs. digital signals | Waves | Middle school physics | Khan Academy

In this video we're going to think about analog versus digital signals and one way to think about the difference is an analog signal is trying to reproduce exactly in some type of a signal what is going on while a digital signal is converting it usually to ones and zeros which then can be converted back so the first thing to realize is.

That almost any type of information it might be how intense a certain color is or how bright it is or it might be a frequency of sound all of that can be represented as numbers so whether you're trying to transmit an analog signal or a digital signal it really is about how do you communicate numbers using some type of signal and as an example let's say.

That you are trying to communicate the number 24 to someone well one way to do it is as an analog signal you could have as time goes on maybe this is some type of voltage across a wire and if you put that voltage right at what the other person receiving it could it interpret it as 24 well then you would transmit it and they.

Might if they get this nice clean signal see it as a 24. now the problem with analog signals is what happens when you have interference so let's say this is a really long wire that you're transmitting it over or you're transmitting it using radio waves and there's a lot of bad weather or other types of interference and so on.

The receiving end even though you transmit something that looks like this that is a clear 24 the other person might get something like this and so this isn't obvious that is a 24 anymore it goes between 20 and 30 and this could be interpreted as static or garbled up message or just doesn't sound.

As clean depending what the 24 is trying to represent or the image isn't as clear if this is representing say the the lightness or the brightness of a pixel now the other option is to convert that 24 into binary so 24 can be represented in binary as one one.

Zero zero zero now we have other videos on khan academy that explain how to convert back and forth between our decimal system that has ten digits zero through nine and the binary system which has two digits zero and one but in case you're curious and you don't have to understand this to know the difference between analog and.

Digital signals and when they might be useful this first place is the ones place just as you're used to but instead of this being the tens place this is the two's place instead of this being the hundreds place this is the fourth place instead of this being the thousands place this is the eighths place and instead of that being the ten thousands.

Place that's the sixteens place so one way to think about it one one zero zero zero means one sixteen and one eight and if you add those together you would get twenty four what would that actually look like as a signal well it could look something like this where the person interpreting it knows.

That over this first time period whatever voltage you're getting that tells you your first digit then over the next time period whatever voltage you're getting tells you the second digit and so on and so forth so this would be one one zero zero zero now why is this useful well let's think.

About the situation where all of a sudden there's interference again now with the interference you could still interpret this exactly as one one zero zero zero remember the person receiving the signal or the system receiving the signal is just trying to determine whether it's getting a one or a zero so even though this is being.

Perturbed right over here it's clear that we are at a one we know that it would not be a point nine or one point one it has to be either one or a zero so it's clear that over this part right over here you're getting a one and then over here you're getting three zeros so they would be able to interpret it as one one zero zero zero.

Which is once again exactly twenty four