All types of information are encoded in a sequence of electrical impulses: there is an impulse (1), there is no impulse (0), that is, in a sequence of zeros and ones. This encoding of information in a computer is called binary coding, and logical sequences of zeros and ones - in machine language.

These numbers can be considered as two equally probable states (events). When writing a binary digit, a choice of one of two possible states (one of two digits) is implemented and, therefore, it carries an amount of information equal to 1 bit.

Even the unit of measurement of the amount of information bit (bit) got its name from the English phrase Binary digit, that is, binary digit.

It is important that each digit of the machine binary code carries information of 1 bit. Thus, two digits carry 2 bits of information, three digits carry 3 bits, etc. The amount of information in bits is equal to the number of digits of the binary machine code.

Transfer of information in an information system.

The system consists of a sender of information, a communication line and a receiver of information. The message must first be converted into a signal in order to transmit it to the appropriate address. A signal is a changing physical quantity that displays a message. Signal– a material carrier of a message, that is, a changing physical quantity that ensures the transmission of information over a communication line. The physical medium through which signals are transmitted from the transmitter to the receiver is called a communication line.

IN modern technology Electrical, electromagnetic, light, mechanical, sound, and ultrasonic signals have found application. To transmit messages, it is necessary to accept a carrier that can be efficiently distributed along the communication line used in the system.

The conversion of messages into signals convenient for transmission over a communication line is carried out by the transmitter.

In the process of converting discrete messages into a signal, the message is encoded. In a broad sense, encoding is the transformation of messages into a signal. In a narrow sense, coding is the display of discrete messages by signals in the form of certain combinations of symbols. The device that performs encoding is called an encoder.

During transmission, signals are subject to interference. Interference refers to any interfering external disturbances or influences (atmospheric interference, the influence of extraneous signal sources), as well as distortion of signals in the equipment itself (hardware interference), causing a random deviation of the received message (signal) from the transmitted one.

On the receiving side, the reverse decoding operation is carried out, i.e. restoration of the transmitted message based on the received signal.

The decision device, located after the receiver, processes the received signal in order to extract information from it as completely as possible.

A decoding device (decoder) converts the received signal to a form convenient for perception by the recipient.

The set of means intended to transmit a signal is called a communication channel. The same communication line can be used to transmit signals between many sources and receivers, that is, a communication line can serve several channels.

When synthesizing information transmission systems, it is necessary to solve two main problems associated with message transmission:

Ensuring noise immunity of message transmission

Ensuring high efficiency messaging

Noise immunity refers to the ability of information to withstand the harmful effects of interference. Under these conditions, i.e. for a given interference, noise immunity determines the accuracy of information transmission. Fidelity is understood as a measure of compliance of the received message (signal) with the transmitted message (signal).

The efficiency of an information transmission system refers to the system’s ability to provide transmission within given quantity information in the most economical way. Efficiency characterizes the ability of a system to ensure the transmission of a given amount of information with the least expenditure of signal power, time and frequency bandwidth.

Information theory establishes criteria for assessing noise immunity and efficiency information systems, and also indicates general ways to increase noise immunity and efficiency.

Baud rate is the speed at which information in binary form is transmitted or received. Typically, data transfer speed is measured by the number of bits transferred in one second.

Bits per second is a unit of information transmission speed, equal to the number of binary bits transmitted by a communication channel in 1 second, taking into account both useful and service information.

Communication channel capacity is the maximum speed of data transfer from source to recipient.

Characters per second is a unit of measurement for the transmission rate of (only) useful information.

Moving to larger units of measurement

There are no restrictions on the maximum power of the alphabet, but there is an alphabet that can be considered sufficient (at the present stage) for working with information, both for humans and for technical devices. It includes: the Latin alphabet, the alphabet of the country's language, numbers, special characters - about 200 characters in total. From the above table we can conclude that 7 bits of information is not enough, 8 bits are required to encode any character of such an alphabet, 256 = 28. 8 bits form 1 byte. That is, 1 byte is used to encode a computer alphabet character. The enlargement of units of measurement of information is similar to that used in physics - the prefixes “kilo”, “mega”, “giga” are used. It should be remembered that the base is not 10, but 2.

1 KB (kilobyte) = 210 bytes = 1024 bytes,

1 MB (megabyte) = 210 KB = 220 bytes, etc.

The ability to assess the amount of information in a message will help determine the speed of information flow through communication channels. The maximum speed of information transmission over a communication channel is called the bandwidth of the communication channel. The most advanced means of communication today are optical fibers. Information is transmitted in the form of light pulses sent by a laser emitter. These means of communication have high noise immunity and throughput more than 100Mbit/s.

Internet speed is the amount of information received and transmitted by a computer over a period of time. Nowadays this parameter is most often measured in Megabits per second, but this is not the only value; kilobits per second can also be used. Gigabits are not yet used in everyday life.

At the same time, the size of transferred files is usually measured in bytes, but time is not taken into account. For example: Bytes, MB or GB.

It is very easy to calculate the time it will take to download a file from the network using a simple formula. It is known that the smallest amount of information is a bit. Then comes the byte, which contains 8 bits of information. Thus, a speed of 10 Megabits per second (10/8 = 1.25) allows you to transfer 1.25 MB per second. Well, 100 Mbit/s is 12.5 Megabytes (100/8), respectively.

You can also calculate how long it will take to download a file of a certain size from the Internet. For example, a 2 GB movie downloaded at a speed of 100 Megabits per second can be downloaded in 3 minutes. 2 GB is 2048 Megabytes, which should be divided by 12.5. We get 163 seconds, which is equal to approximately 3 minutes.
Unfortunately, not everyone is familiar with the units in which it is customary to measure information, so we will mention the basic units:

1 byte is 8 bits
1 Kilobyte (KB) corresponds to 1024 bytes
1 Megabyte (MB) will be equal to 1024 KB
1 Gigabyte (GB) correspondingly equals 1024 MB
1 Terabyte – 1024 GB

What affects speed

The speed at which the Internet will work on the device depends primarily on:

From the tariff plan provided by the provider
From the channel capacity. Often the provider provides shared speed to subscribers. That is, the channel is divided among everyone, and if all users actively use the network, then the speed may decrease.
From the location and settings of the site the user is accessing. Some resources have restrictions and do not allow you to exceed a certain threshold when downloading. Also, the site may be located on another continent, which will also affect loading.

In some cases, the data transfer speed is influenced by both external and internal factors, including:

Location of the server being accessed
Setting and channel width Wi-Fi router, if the connection occurs “over the air”
Applications running on the device
Antiviruses and firewalls
OS and PC setup

In the case of information transfer speed, these “nice numbers” are confusing. Of course, the situation here is still different - this is confusion between the standard (where the speed is named according to what it is at the link level) and reality, but the meaning is very similar: the number on the sticker does not correspond to what you see with your eyes when you turn on the computer. Let's try to sort out this confusion.

There are two types of connection - using a cable, and over the air, wirelessly.

Connection by cable.

In this case, there are fewer problems with numbers. Connection occurs at speeds of 10, 100 or 1000 megabits (1 gigabit) per second. This is not “Internet speed”, not the speed of opening pages or downloading files. This is only the speed between the two points that such a cable connects. From your computer, the cable can go to the router (modem), to another computer, or to the entrance to the provider’s equipment, but in any case, this speed only indicates that the connection between these two points occurred at the specified speed.

The data transfer speed is limited not only by the type of cable, but also quite strongly by the speed of your hard drive. On a gigabit connection, the file transfer speed will be limited to this, and achieving real 120 megabytes per second is only possible in some cases.

The connection speed is selected automatically depending on how your connected devices “agree” on the slowest one. If you have a gigabit LAN card(and now most of them are in computers), and on the other end there is 100 megabit equipment, then the connection speed will be set to 100mbit. None additional installations there is no need to set the speed, if this is required - this is an indicator that there is a problem with the cable, or with the equipment at your place or at the other end, and therefore the maximum speed is not automatically set.

Wireless connection.

But with this type of connection there are much more problems and confusion. The point is that when wireless connection The data transfer speed is approximately two times less than the standard figure. How it looks in real data - look at the table.

As you can see, everything is very sad and ugly, and the vaunted “N” does not show anywhere near the numbers that we would like to see. In addition, this speed is ensured under environmental conditions close to ideal: no interference, no walls with metal between the router and the computer (direct line of sight is better), and the shorter the distance, the better. In a typical three-room apartment in a reinforced concrete building, a wireless access point installed in the far part of the apartment may be almost imperceptible from the opposite part. The “N” standard provides better coverage, and this advantage is more important to me personally than speed; and high-quality coverage has a good effect on speed: where the data transfer speed when using equipment with “G” is equal to 1 megabit, only using “N” can increase it several times. However, it is not at all a fact that this will always be the case; it’s a matter of ranges; in some cases, such switching does not produce results.

The speed is also affected by the performance of the device distributing the Internet (router, access point). If you actively use torrents, for example, the speed of data transfer through the router can drop significantly - its processor simply cannot cope with the data flow.

The speed is also affected by the selected encryption type. From the name itself it is clear that “encryption” is the processing of data in order to encode it. Different encryption methods can be used, and hence different performance of the device that performs this encryption/decryption. Therefore, it is recommended to set in the parameters wireless network WPA2 encryption type is the fastest and most secure this moment encryption type. As a matter of fact, according to the standard, any other type of encryption will not allow “N” to turn on at “full power,” but some Chinese routers do not care about the standards.

One more thing. In order to get all the benefits of the N standard (especially for equipment that supports MIMO), the access point must be set to “N Only” mode.

If you selected “G+N Mixed” (any “mixed” mode), there is a high probability that your devices will not try to communicate at maximum speed. This is a fee for standards compatibility. If your devices support “N”, forget about the other modes - why lose the benefits offered? Using both G and N equipment on the same network at the same time will deprive you of them. However, there are routers that have two transmitters and allow you to work in two different frequency ranges at the same time, but this is rather rare, and their price is much higher (for example, Asus RT-N56U).

Other connection types.

In addition to those described, of course, there are other types of connection. Outdated option – connection via coaxial cable, an unusual connection option through the building's electrical network, many connection options using mobile networks - 3G, new LTE, relatively unpopular WiMAX. Any of these connection types has speed characteristics, and any of them operates with the concept of “speed BEFORE”. You are not being deceived (well, formally they are not being deceived), but it makes sense to pay attention to these numbers, understanding what they really mean.

Units.

There is confusion caused by the incorrect use of units of measurement. This is probably a topic for another article (on networks and connections, which I will write soon), but still, here (concisely) it will be appropriate.

IN computer world accepted binary system Reckoning Smallest unit measurements-bit. The next one is a byte.

Ascending:

1 byte = 8 bits

1024 bits = 1 kilobit (kb)

8 kilobits = 1 kilobyte (KB)

128 kilobytes = 1 megabit (mb)

8 megabits = 1 megabyte (MB)

1024 kilobytes = 1 megabyte (MB)

128 megabytes = 1 gigabit (gb)

8 gigabits = 1 gigabyte (GB)

1024 megabytes = 1 gigabyte (GB)

Everything seems to be clear. But! Suddenly it turns out that there is confusion here too. Here's what Wikipedia says:

When designating telecommunications connection speeds, for example, 100 Mbit/s in the 100BASE-TX standard (“copper” Fast Ethernet) corresponds to a transmission speed of exactly 100,000,000 bps, and 10 Gbps in the 10GBASE-X (Ten Gigabit Ethernet) standard - 10,000,000,000 bps.

Who to believe? Decide for yourself what is more convenient for you, read the same Wikipedia. The fact is that what is written on Wikipedia is not the ultimate truth, it is written by people (in fact, anyone can write something there). But in textbooks (in particular, in the textbook “ Computer networks” from Olifer V.G., Olifer N.A.) – the calculus is normal, binary, and in 100 megabits there are 12.5 megabytes, and exactly 12 megabytes you will see when downloading a file over a 100-megabit local area network, in almost any program.

Various programs display speed differently - some in kilobytes, some in kilobits. Formally, if we are talking about *bytes, a capital letter is used, about *bits, a small letter (designation KB (KB, sometimes kB or kB, or Kbyte)) - means “kilobyte”, kb (kb, or kbit) - “kilobit” , etc.), but this is not an ironclad rule.

Hello, dear readers of the site!

You were probably interested baud rate over the network (including the Internet), write speed to a flash drive (or HDD). Today we will look at the speed of information transfer in computer technology and we'll find out how many megabytes are in a megabit?!

The information from the previous lesson will be useful to you; if you haven’t read it yet, be sure to start there.

Let me remind you that in the last IT lesson we dealt with bits, bytes and multiple prefixes K, M, G, T and found out how many bytes are in a kilobyte (here is lesson 15).

Do you remember? Then let's begin!

Baud Rate - Units

The minimum unit of measurement for data transfer speed is taken to be bits per second, (which is not surprising, because a bit is the smallest unit of measurement of the amount of information).

Bits per second or bps(in English bits per second or bps) is the basic unit used to measure the speed of information transfer in computing.

Since when measuring the amount of information, not only bits, but also bytes are used, the speed can also be measured in bytes per second. Let me remind you that one byte contains eight bits (1 Byte = 8 bits).

Bytes per second or Bytes/s(in English byte per second or Byte/s) is also a unit that measures the speed of information transfer (1 Byte/s = 8 bits/s).

* I would like to ask you to immediately note that when reducing bits written with a small letter " b» ( bps), A bytes written with a capital letter " B"(M B/s).

Copying prohibited

Definition 1

Information transmission speed is the information volume that is transmitted per unit of time.

Introduction

Information is a basic term in the discipline of computer science, which does not have an exact formulation, but at the same time, information is:

1. Providing new facts and knowledge.
2. Data about objects and events in the environment that increase people's awareness.
3. Data about the objective reality of the external environment, reducing gaps in knowledge about various phenomena and helping to find optimal solutions.

The term “information” is considered a general scientific one, as it is used in various scientific disciplines. But, nevertheless, each scientific discipline associates this term with different conceptual aspects. For example, physics believes that information is antientropy (it determines the orderliness and complexity of the system).

In a community of people, processes of information exchange constantly occur. A person receives information from the external environment through his senses, analyzes it and develops the necessary decisions, which are then translated into practical influences on the external environment. Information processes represent the collection, transmission, storage and processing of information data. Information transfer refers to the operation of transmitting messages from a source to a receiver using special communication channels. Information data can be transmitted in the form of various signals, which are formed from sound, light, ultrasound, electromagnetic waves, text, graphics, and so on. It is possible to use the atmosphere, various cable networks, a person, his nerve cells and so on.

Definition 2

By storing information we mean the operation of fixing a message on some physical media. Paper and other surfaces, magnetic tape, laser discs, hard drives and more.

Note 1

Information processing refers to the operation of generating a new message from a set of existing ones. When processing information, there is a possibility of increasing its quantity. The result of processing messages of one type may be the generation of messages of another type.

Information transfer rate

Note 2

The smallest unit of measurement for data transmission speed is one bit per second. A bit is considered the smallest unit of measurement information volume. Bit/sec is the basic unit for measuring the speed of information transmission in the field of computer technology.

But since the amount of information can also be measured in bytes, there is a corresponding unit of measurement for speed, bytes per second. For reference, one byte is eight bits. And, accordingly, 1 Byte/s = 8 bits/s. You should also pay attention to the fact that in the abbreviated format, a bit is written with a small letter (bit/sec), and a byte is written with a capital letter (B/sec). But since bits and bytes represent relatively small amounts of data, special multiplying prefixes are used to work with large information volumes. The decimal format of prefixes is well known to us from our everyday life when measuring length, weight, and so on.

In particular, such prefixes are:

• kilo (k), means that the number must be multiplied by a thousand (for example, one kilogram is a thousand grams).
• mega (M), means that the number must be multiplied by a million (it is curious that this term was introduced relatively recently, in 1960).
• giga (G), means that the number must be multiplied by one billion (even more strangely, this term originated back in 1947, that is, thirteen years before the term mega).

In the field of electronic computers, binary format prefixes are also used. These are the following terms:

• Kibi (Ki) means that the number must be multiplied by 1024 (that is, two to the power of ten).
• Mebi (Me), means that the number should be multiplied by 1,048,576 (220).
• Gibi (Gi), means that the number must be multiplied by 1,073,741,824 (230).

Note also that this binary terminology was introduced by the International Electrotechnical Commission (IEC) in 1999. Decimal prefixes can also be used to measure the speed characteristics of information transmission. If binary coefficients are used to indicate the amount of information data, then when determining the speed of information transmission, decimal coefficients are usually used. That is, one kbit/sec corresponds to 1000 bits/sec. Accordingly, one megabit per second contains one million bits per second, and one gigabit per second is one billion bits per second. When using bytes, everything will be exactly the same, but with abbreviations there will be a capital letter B and, of course, we must remember that a byte contains eight bits.

That is: 1 kilobyte per second (kbyte/sec or kB/s or kB/s) is equal to 1000 bytes/sec.

In order to convert kilobits and megabits to kilobytes and megabytes you need to:

• To convert the amount of information in bytes into bits, you need to multiply them by eight.
• To convert the information volume in bits to bytes, you need to divide by eight.

For example, 100 Mbit/sec =100/8 =12.5 MB/sec.

Binary coefficients to indicate the speed of information transfer are not used very often. For example, 1 kibibit per second (1Kibit/sec or 1Kib/s) = 1024 bit/sec. There is one danger here. Sometimes the use of binary odds is simply not indicated and there is a possibility that the symbol “M” means not “Mega”, but “Mebi”.

Internet speed

Since the advent of the Internet, the speed of data transfer on the network has been measured in bits per second. And the amount of data stored on a hard drive (or other storage medium) is usually counted in bytes. Therefore, you should remember that when connecting to the Internet, in the offered tariff plans the speed is indicated in Megabits per second, and when actually downloading data software indicates the speed in MB per second. That is, it is stated, for example, that the Internet speed will be 20 Mbit/sec, but in reality we see 2.5 MB/sec. But there is no trick here, it’s just an eightfold difference between a bit and a byte.