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What is an Analog to Digital Converter?

By Charity Delich
Updated May 16, 2024
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An analog to digital converter, also referred to as an ADC or an analog signal converter, is used to turn analog signals into digital signals without changing the essential message of the underlying data. For example, voices work on analog signals, and computers are typically designed using digital technology. If a voice is recorded on a computer, an analog to digital converter device is required in order for the computer to understand the voice. Usually, analog to digital converters are operated by electricity, although some of these gadgets may be non-electronic or only partially electronic.

Analog and digital signals operate differently from each other. Analog signals are used when creating, storing, or transmitting data of varying frequency. In general, analog technology works by deliberately varying the strength or amplitude of a signal. Analog technology translates audio sounds, such as the human voice, into electronic pulses. Telephone, radio and television are some examples of industries that have traditionally used analog technology.

Digital signals, on the other hand, are associated with a type of technology that creates, maintains, and transmits data in positive or negative states. The number zero represents a non-positive state while the number one indicates a positive state. When digital data is transmitted or stored, the action is expressed as a binary string of ones and zeros. Digital technology is often used for newer types of media, like HDTV, direct broadcast satellites, or fiber optic transmissions. Devices based on digital technology usually have less unwanted noise, and they allow users to easily store large amounts of data.

An analog to digital converter can be essential when working with multiple pieces of electronic equipment that operate on different technologies. For example, connecting a computer and a phone line may require an analog to digital converter. Telephones usually operate using analog signals, and computers are digitally-based. A digital computer cannot make sense of analog phone signals until those signals are converted into digital form, using an analog to digital converter. These types of converters are often called modems.

A digital to analog converter or DAC is the opposite of an analog to digital converter. Digital to analog converters work by converting digital signals into analog signals, and they are required whenever a digital signal must be changed to an analog signal. For instance, compact discs (CDs) are typically digital. When a CD is played, the CD player reads the digital information on the disc and then converts it into analog signals. As a result, the CD can be heard.

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Discussion Comments
By sunnySkys — On Feb 22, 2012

@Mammmood - That's good to know. My moms side of the family loves to take home movies, and we have a ton of them that are VHS. In fact, some of the ones that are on VHS were actually taken on spools of film first and then we had them converted to VHS.

Obviously our VHS tapes are getting old, and VCRs aren't that easy to find anymore. I'm glad to hear that we could probably convert our old VHS tapes from analog to digital in the comfort of home!

By JaneAir — On Feb 22, 2012

@starrynight - Me too. I don't know if I could define digital if someone asked me to in conversation. But like everyone else, I think I know what it means.

Anyway, it seems like since the human voice is analog, most technology involving the human voice needs an analog to digital converter. Compact disks and VOiP phone systems have already been mentioned.

From what I understand, although radio is traditionally analog too, there are digital radio services available. I feel like it's only a matter of time before radio goes totally digital just like cable television.

By starrynight — On Feb 22, 2012

Like a lot of the other commenters, I also had to get an analog to digital converter for my television when my cable company went digital. I never really thought about what the analog to digital converter was actually doing though. I just knew I needed it to watch television!

It sounds like analog to digital conversions happen a lot more than I thought though. I had no idea a voice was considered analog, or that the data on a compact disk had to be converted to analog in order for us to hear it.

Along with the rest of the world, I say and hear the word digital all the time, but I never really stop to think about what it actually means!

By Mammmood — On Feb 21, 2012

@MrMoody - I don’t think you need a camcorder or a computer frankly. From what I understand you can get a high speed analog to digital converter device.

You stick your VHS tapes in one slot and your digital tapes in the other, press record, and it will quickly convert your tapes to digital. I think this is the best option really if you’re planning to convert a whole bunch of home movies to digital. You should be able to get everything done in a few hours.

By MrMoody — On Feb 21, 2012

@everetra - I have a digital camcorder too. I don’t know if it has an analog to digital converter chip; I’ll have to check it out.

But I am definitely sold on digital technologies over the analog tapes. With digital, like the article says, your video is encoded as ones and zeroes.

What this means is that you can create as many digital copies off the original digital tape, and each copy will retain the same quality as the original. With analog, however, each subsequent copy (or “generation”) will be a little less clear.

I’ve also heard that digital tapes last longer too. I believe you can only get ten years out of the analog tapes, maximum.

By everetra — On Feb 20, 2012

@SkyWhisperer - That’s one reason I don’t use VOIP technology, although I am sure that the analog to digital converter design has improved since the early days.

I’ve been interested in converting my old video tapes to digital however. I know that you can do it on a computer, using a special card, but I’ve wanted to do it without downloading the video to my computer first. I don’t need to do any editing or stuff.

Well one day I found out that I had an analog to digital converter on my camcorder. It’s the jack for “analog in” and it allows me to play my VHS video straight into the camcorder. After I press “record” the incoming signal is stored on digital tape.

It works. Of course it’s cumbersome in its own way since I have to use my camcorder, but at least I don’t need to download it to the computer.

By SkyWhisperer — On Feb 20, 2012

I worked in the telecommunications industry for quite some time. The analog to digital converter circuit was quite common in VOIP, or Voice Over Internet Protocol transmissions.

Basically with VOIP you want to take your analog voice calls and convert them so that they can be sent as digital data packets. In order to do this the analog signal is converted to digital and then sampled or “chopped” up if you will, in little pieces, and assembled into data packets.

The packets are then sent over the Internet and then reassembled at the receiver’s end. Of course at that point the digital packets have to be converted to analog again, so there is a device that will do that.

The only problem with this approach to telephone communications is that it’s subject to latency or delay. Since your voice is traveling over the Internet, then if there is any congestion, the packets will be delayed in the process.

By jcraig — On Feb 20, 2012

@cardsfan27 - I guess it is obvious, but that all has to do with the way the signal is sent. With the older analog systems, all of the cable waves where sent through the air. Once they got to your house, the antenna picked them up and put them into a form that was recognizable on your TV. It might happen in the case of a storm or if something else was blocking part of the signal that some of the cable waves wouldn't make it to your house, so they would get left out of the final picture. That is what caused the fuzziness.

Now that everyone has to have the TV analog to digital converters, what happens is that the waves are sent through the air and hit the antenna and then are sent to the converter box. Once they are there, the box puts together all of the pieces and sends it to the TV. The main different here, however, is that if all the pieces aren't there, it doesn't send a picture.

All in all, digital TV should usually be better because you'll always have a clear picture even if the screen might go black every now and then.

By cardsfan27 — On Feb 19, 2012

@JimmyT - All of that makes sense, I guess. I think there has to be something missing, though. I can sing a note at 440 Hz, but so can a lot of other people. Our voices don't sound the same, though, so there has to be something else that happens in the computer so that it can also pick up the timbre of someone's voice.

I wasn't aware that all of this digital and analog stuff could apply to normal sounds, though. I just thought about it from the perspective of cable signals. I remember when they switched the broadcasting signals, I had to go out and get an analog to digital TV converter. I never knew what it really meant until I read this, though.

What I don't understand now, though, is why whenever the signal gets weak, the entire station goes out. I don't have a cable subscription, so watching the major stations through the antenna is my only way of watching TV. Before, when it was storming or something, the station might get fuzzy, but the whole screen wouldn't go black. I'm curious if anyone knows why.

By JimmyT — On Feb 18, 2012

@TreeMan - I am not any kind of a computer expert, but I think I know the basics of how computers work well enough to try to answer your question. I'm not sure what exactly analog sound means, but I am guessing from the article that it is basically just any sound with wavelengths.

If you have a microphone or something connected to your computer and you speak into it, the analog sound gets converted into some sort of new format. Obviously, the sound waves themselves can't travel through a microphone cord. Once they make it into the computer, they go through some sort of a analog to digital signal converter that takes the various wavelengths at very small intervals and converts them into binary code.

For example, say one small fraction of your voice has a wavelength of 440 Hz, it would convert that into a code of 1s and 0s that it new meant 440 Hz. Then, when you want to replay the sound, it quickly converts all the 1s and 0s back into an analog signal that can go through your speakers.

By TreeMan — On Feb 18, 2012

Wow, I never realized there was so much that went into us being able to hear all of the different types of media. I wasn't aware that our voices where considered to be analog. What exactly does that mean? I have heard the term used a lot of time, but I never really understood what it meant. I get the digital part well enough. It just means that things are converted into binary code.

Also, how does an analog to digital converter card or whatever it is actually take a human voice and put it into a form that is digital, but still sounds the same? That's what always interested me. I guess my real question is, what parts of our voice are turned into 1s and 0s, and how does the computer know how to make all of those numbers into a form that is recognizable to us?

Maybe not, but it seems like whoever came up with the technology to convert a human voice into a digital format must have been pretty intelligent.

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