Main content

# Digital and analog information

Analog and digital signals differ in how they represent information. Analog signals, like the hands of a clock or sound waves, can show any value within a range. Digital signals, like a digital clock or digitized sound, only show specific, separate levels. Sound waves can be digitized for more reliable storage and processing. Created by Khan Academy.

## Want to join the conversation?

- Is this why when you hear a recording of someone's voice, etc. it doesn't sound quite the same as if it were to be in real life?(18 votes)
- Yes! Especially if the recording is on a low quality (or old) recording device, which are not as capable of capturing the waves as precisely.

Although, if you have a*really*good platform, it can become hard to differentiate the two.(30 votes)

- how is the information lost in translation?(6 votes)
- Compare the set of real numbers with let's say the set of integers. If we are talking about numbers one and two in these sets we are still talking about 1 and 2 but in R there are infinite numbers between 1 and 2 which are lost in Z... so some information is lost in translation.(14 votes)

- Can you turn digital wave into an analog wave, or is it a one-way process?(6 votes)
- Digital to analog conversions can be performed using resistor networks, and the conversion to an analog signal is usually in the order of nanoseconds. Since the digital information is a step approximation of the input signal, the resulting output from a D to A converter reflects this step nature of the signal. So no, it isn't a one-way process.

I hope that helps!(11 votes)

- How can I tell the difference between an anologe and digital(4 votes)
- Analog information expresses information in a continuous way, like an arrow pointing to a point on a line. Think of it as decimals. On the other hand, digital information is expressed only using a few points on that line. You can also think of it as using only whole numbers.(1 vote)

- How can I tell the difference between an anologe and digital(5 votes)
- An analog clock is a clock with the hands that turn around in a circle. A digital clock is a clock that just tells you the time by stating the numbers.(5 votes)

- The Analog can tell the time and the Digital can tell the time too?(5 votes)
- Does an Analog clock really have infinite values? It only goes from 12 AM - 12 PM(4 votes)
- Yes, it does. The hours and minute hands can position themselves in an infinite amount of fractional locations (e.g.3:01.001,3:01.002,3:01.003, etc).(5 votes)

- why was the first one so lazy and the second one was so kind of lazy but not to much but why is the third one is like a rectangles.(4 votes)
- can u turn waves into digital or is it a one way thing(0 votes)
- You can turn analog signals (waves) into digital signals and vice versa!

An example of this is a microphone + speaker setup where the microphone picks up sound waves (analog signals) and turn it into digital signals. Then the speaker turns the digital signals into analog ones.(7 votes)

- How does the digitized version of the wave stay perfectly intact(2 votes)

## Video transcript

- [Instructor] In this
video, we're going to talk about analog versus digital. Something that's analog can be any value within a given range
while something digital is represented by a number of
discreet or separate levels. To distinguish these two ideas, I like to think about clocks. An analog clock has the
numbers in the hands and it's analog because the motion of those hands is continuous. They can sweep across the circle representing any of infinite
times on that clock. For example, between 3:06 and 3:07, the minute hand is actually
going to be at some point between those marks on the clock showing one of the
infinitely possible times that the clock can represent. Compare that to a digital clock. A digital clock is only going
to show you 3:06 or 3:07. It will never display any of
the many fractional seconds between those two times. Digital only takes on
certain discrete values and it has a finite
number of those values. So an analog wave or
signal will smoothly sweep across the infinitely many
possible values it has while a digital wave or signal will only be at one of a
number of discrete values. So the shape of the wave will
be more square or step like. Let's check out an example so this makes a little more sense. I like music. So we're gonna talk about sound. Sound is an analog signal or wave. So if we look at a graph
of sound, volume over time, it's going to have a smooth
continuous analog wave form, both the amplitude or the
volume, and the frequency, what we hear as pitch
are changing continuously between infinite possible values. All right, and that's because sound waves, the vibration of particles
propagating through the air actually changes continuously. The very first sound recording
and reproduction technology imprinted that analog wave
directly onto a material. For example, records imprint
that sound wave into vinyl and cassettes imprint
the sound wave onto tape. A major drawback of this technology is after the sound to play back
exactly as it was recorded, that wave form needs to
stay untouched, right? So think about scratching vinyl
or smudging a cassette tape, that's directly deforming the wave. So you'll never be able
to reproduce the sound exactly as it was recorded. So, technology advanced and
sound waves became digitized. Here's how. All right, so recall
our analog sound wave. We have a smooth analog wave
that's taking on any number of infinitely possible
values within this range. In order to digitize this wave, we're going to ascribe
numbers to the amplitude at different points, all right? Watch this magic. So we go over here and make a scale. So we're breaking up the amplitudes into discrete possibilities. Then we can go through the
wave and at specific points of the wave measure what is the amplitude based on that scale. So over here, we're at the
first point of the scale. At this peak, we're at the
second point of our scale. Then the first, the third,
the second, the fourth, back down to the first. Now that we have this way
broken up into levels, right? We can ascribe the
numbers and we effectively turn this analog wave
into a set of numbers, one, two, one, three, two, four, one. Our wave has been digitized. Now that digitize wave can be played back through a speaker to
recreate the analog wave. As long as the sampling
happens at a quick enough rate, humans can't tell the difference. All right, so the digitization of waves is all about ascribing specific numbers to some of those mechanical
properties of the wave. The important thing here
is that now that the wave has been digitized, the
digitized sound wave can be reliably stored, processed, and communicated with computers. So some information is
lost in translation, but once the wave is digitized, it's quality will never degrade, okay? And that allows for a lot
more reliable technology because the wave is
represented with numbers instead of it being physically
imprinted on some material. So humans prefer to store
information like sound digitally, and there are ways to turn analog signals, which can represent any of
infinite possible values into digital information, which is useful because
information is stored only at a number of
discreet or separate levels.