Analog and digital

Lasa Oiarbide, Aitzol

Elhuyar Zientziaren Komunikazioa

Analog and digital systems. They are neither past nor future. Currently, both systems are used, which are often used simultaneously. They are used to store or transport information in different formats and supports.
Analog and digital
01/11/2006 | Lasa Oiarbide, Aitzol | Elhuyar Zientzia Komunikazioa

(Photo: MEC; Archive)
The word analog comes from the analogy and the analogy is the relation of similarity between different things. In the scientific field, something is analogical if it depends on the continuous variations of a physical magnitude. For example, a signal is analog if it depends on the difference in potential, frequency, current, or load variation. In addition, this signal must be continuous, that is, without cuts.

Imagine a recording studio. There, the sound waves press on the microphone. In turn, these pressure changes represent a continuous change in the tension that goes through the inside of the microphone. Finally, the recording is done according to this analog signal.

Instead of recording, the analog signal that has been created in the microphone can be transmitted using radio waves. In short, the wavelength of the electromagnetic waves is a physical magnitude that suffers a continuous change, so it meets the above definition. Radio waves are also electromagnetic waves and are used to transport radio and television signals. In this case, the signal coming from the microphone causes a continuous change in the radio wave, which can be barred at a great distance.

The analog signal depends on a variable physical magnitude, so interferences directly affect it. For example, the radio signal being emitted at a wavelength of 91.4 megahertz will receive interference from another radio signal of the same wavelength. That is why radio licenses are divided, among other things, to avoid overlapping of signals. But interferences are inevitable both in the case of radio waves and in any other analogue signal.

Among others, analog indicators have been used in cars. There are more and more screens. They report on speed and gasoline, but they also report on other information such as if it rains outside or if there is ice on the road.
MEC

Space radiation is constantly penetrating the Earth's atmosphere and part of it is made up of radio waves. Therefore, the radio of the kitchen cannot avoid interferences, at least those that come from space. On the other hand, music is usually recorded at night. In fact, at night noise is reduced in cities, thus reducing interference in the microphones of the study. Many times these interferences are not heard by man, but are recorded in the analog microphone signal, to the detriment of sound quality. Another reason to make night recordings is that singers have a finer voice at night than at day. But that's something else.

The analog signal can be digitized

Like radio waves, the visible light is also an electromagnetic wave. Each wavelength that forms the band of visible light corresponds to a color. An analog photo camera records the wavelengths of visible light in a photosensitive film. It is an analog process because in the film the information of the wavelengths is written. But a digital camera processes that information in another way.

Digital systems do not require rollers to transport information.
From file
The digital camera has millions of sensors, one per pixel, distributed in columns and rows type network. During exposure, each sensor receives the information corresponding to its pixel. In fact, a sensor receives the light corresponding to a band of electromagnetic spectrum, that is, it receives several colors, like the shades of the orange color. It stores one of the wavelengths collected in the sensor and converts it into electric charge. This electrical load is quantified and, once amplified, it is converted into number by the camera software. That is, the diversity that had the light has been lost and instead a single color will appear for each pixel.

This process is not analogue. It does not record all the shades of light. On the contrary, it records only one of these tonalities for each pixel and, in addition, it archives this information as a number on a hard disk. This process is digital.

At present, a digitization is taking place in all areas of technology. Examples of this are digital cameras, but there are more examples. For example, television and radio stations have begun to transmit the digital signal.

The information society is digital

The HiPath 4000 Switchboard manages the usual phone and online. It is, therefore, able to take advantage of the analog and digital system at the same time.
Siemens Siemens

As comes from the analogy, the digital word comes from the digit. Digit or digitus, is the Latin word that means the finger, or also counting with the fingers. Therefore, a digital system does so, storing or transmitting information through numbers.

Computers write this information in binary numbers, that is, using digits 0 and 1, and normally need a lot of impressive numbers. For example, a high-resolution photo can cover 1.5 megabytes on the hard disk. This means a million five hundred thousand bytes. Considering that a byte is a number of 8 binary digits, this means that to save the photo a number of 12 million digits has been used.

Of agreement. But, what can be done to transmit such a long sequence? The transmission system must be fast or not effective. For example, if a simple computer modem transmits 28 kilobytes per second, that is, 28,000 bytes or 224,000 digits, it will take a minute to move the previous photo from one place to another. It does not seem very effective for current technology. The transmission would be effective, for example, in 5 seconds. To do this, the system should move 300 kilobytes in a second, that is, about two and a half million digits.

Today, digital devices are essential for, for example, learning or obtaining information from the Internet.
From file
If this transmission is desired at a long distance, pulses, such as the electric pulse, are normally used. The pulse indicates 1 digit and the absence of pulse 0 digit. This type of endless sequences are constantly transmitted by satellites.

To avoid errors during transmission, software does not encode information in any way. If an error has occurred in a transmission, instead of 1 a 0 may appear. The software must be able to recognize the error and must correct it. Otherwise, every time the transmission is carried out, information will be lost.

More than format changes

On the one hand, digital technology is seen as a change of format; instead of being stored in analog systems, information is stored on computers using binary numbers. When making a backup on the hard disk, a digital system offers a safer way to store the information.

For example, the negatives of photos and cassettes are made of perishable material. With the passage of time this material will inevitably be damaged. However, the information stored on a hard disk will always be available, as you can make as many copies as you want without losing the information.

Images, music, voice… any kind of information can be stored in a digital system.
Siemens Siemens

But on the other hand, digital technology is more than that, since it has the help of software to treat information. Referring back to the photos, we can use IT applications on a digitally stored photo to improve the quality of the photo, illuminate the dark photo, focus the wrong photo or recover the old photo.

To cite more examples, monitors in medicine are currently used in a much more effective way than in other times. In addition to making black and white x-rays, the part of the patient's body can now be monitored in three dimensions, and the image appears in color. If, once the scanner was used, such information would not be treated digitally, it would not be possible to obtain such images.

It is also possible that the image captured by a camera is not for people. Robots use digital cameras to "see" it. In this case the image also goes directly to the “brain” of the robot, that is, to a computer. There, the software will analyze the image and tell the robot what to do. All these things would be unthinkable in an analog system.

Error resolution in the digital system
When writing information in binary numbers, a digital system uses no combination. First, the sequences --words - must have a given length. Usually the sequences are 8 digits (or 16, 32... that is, the textures of both). This is easy to understand because a byte has 8 binary digits and the numbers are saved on the computer by bytes.
In addition, the words contain distinctions that the system can know -- in the dictionary of the system. Thus, the system only transmits words from the dictionary. For example, it may be the dictionary word 01100101, but not the word 01101101.
Normally, to determine whether the words are in the dictionary, the system performs a series of operations with the digits of the word, adding this additional information to the word. For example, if with digits of 01100101 control operations are performed and the result is 010, the number 01100101 010 will be sent.
To check if a transmission error has occurred, the receiver will repeat control operations and verify the result with the last three digits. For example, it is the last letter of the identity document number, a control digit that serves to check whether the number is true or false.
With the control digit, if a transmission error occurs, the system software will realize and try to correct it. As a consequence of error, a word of the dictionary is transformed by another other than that of the dictionary and the system will replace the faulty word with the word of the nearest dictionary. Of course, the more appropriate the algorithm used by the software, the more reliable the system will be.
Digital culture Digital culture
There is a new generation in the world who has learned to search the internet before the orthographic rules. For this generation, digital systems are the daily bread. That seems, at least, that the concept of digital culture has begun to be used to define the adherence of young people to new technologies.
In this sense, the American writer and mathematician John Allen Paulos affirms that a significant number of people living in today's technological society have not enough mathematical knowledge to realize the things that surround them. Can a person unknown in numbers and mathematical logic be part of digital culture? Note that the digital word only means that, the number.
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