The Analog to Digital Conversion Process

The Analog to Digital

Conversion Process

ByLafayette Larrimore

WELCOME

Hello my name is Lafayette Larrimore

and I am from the sunny city of Miami

Florida USA.Thank you for reviewing my

simple project. It is a short journey into

the amazing world of sound. We travel

along the path of how analog sound is

converted into digital sound. Let us

begin on this exciting adventure!!

Analog Sound

Input Transducer

Analog to Digital Converter

Digital Sound

Roa

d to

Dig

ital

Soun

d

THE ANALOG SIGNAL

The whole process of converting sound from analog to digital starts with the analog signal. In short, an audio signal is a representation of sound typically as an electrical voltage. It is these electrical voltages that will be sampled and then converted into binary form so the computer can understand. The signal must first enter the pathway. This is accomplished by what is called an input transducer.

INPUT TRANSDUCERS

A transducer is a device that converts energy from one form of energy to another form of energy. In this situation we are dealing with sound energy to electrical energy. In our field this is most commonly accomplished by using microphones.

MICROPHONESTo put it simply, a component in the microphone called the diaphragm vibrates when sound wave makes contact. These vibrations are converted into electrical currents which become the audio signal. This signal goes in to the next step in the process, the analog to digital converter.

A TO D CONVERTER

An analog-to-digital converter is a device that converts a continuous physical quantity (usually voltage) to a digital number that represents the quantity's amplitude. Basically it takes analog sound and through various processes sample it and convert it to digital representation of the analog sound.

A TO D CONVERTER

As you can see from the previous slide The sound comes in to the A/D converter via an audio input (in this case a microphone) as analog, sampled and then converted to digital (a language computers understand). The process is then reversed, digital to Analog and sent to an output device (speakers). headphone etc..

SAMPLINGIn converting analog signals to digital representations, we use binary digital words to store the measured signal amplitude at intervals. These intervals are determined by the sample rate. Think of it as cutting a sound wave into many individual units over time . How many sample units occur during a certain time period is the sample rate

SAMPLINGTherefore if you see or are told a CD has a 44100Hz, it simply means 44100 points will be captured per second. In the case of distance each sampled point is 1/44100 of a second apart. The more samples taken,(the higher the sampling rate) the better the material will sound (up to a point).

SAMPLINGAs you can imagine 1/44100 of a second is not much time but it allows for a lot of sound instances to be sampled thus you end up with a very accurate representation of the source that was sampled. Each sample is measured and stored as a numerical value that represents the audio amplitude at that particular moment. The amplitude of each sample is converted to a binary number that can be read by computers.

DIGITAL SIGNAL

Once the audio has been sampled, the A to D encodes it into a digital representation of this sound call the digital signal. Now not only can the computer understand the sound it can manipulate it in various was ranging from storing it, adding effect or preforming this whole process in reverse and convert it back to analog to be heard by us.

DIGITAL TO ANALOG

This is beyond the scope of this assignment but I felt it should be mentioned briefly. Think of digital to analog as the reverse of analog to digital in terms of steps. The digital audio signal is amplified then converted back to into physical wave forms via an output transducer( loudspeaker, headphones etc..).

REFLECTIONAgain thank you very much for reading my assignment. I tried to make it as simple and as short as I possible could without sacrificing content. Just remember that sound goes through several steps from analog to become digital. Source – microphone - a to d converter with the result being digital. Good luck with the rest of the course!!