How to determine the speed of the transmitted information. How to calculate the baud rate. Introduction of new material

Definition 1

The information transfer rate is the amount of information that is transmitted per unit of time.

Introduction

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

1. Providing new facts and knowledge.
2. Data on objects and events in the environment that raise human awareness.
3. Data about the objective reality of the external environment, narrowing gaps in knowledge about various phenomena and helping to find optimal solutions.

The term "information" is considered general scientific, as it is used in different scientific disciplines. But, nevertheless, each scientific discipline associates this term with different conceptual aspects. For example, physics believes that information is anti-entropy (it determines the order and complexity of the system).

In the community of people, information exchange processes are constantly taking place. A person receives information from the external environment through his senses, analyzes it and develops the necessary decisions, which are then embodied in practical influences on the external environment. Information processes are the collection, transmission, storage and processing of information data. The transfer of information is understood as the operation of broadcasting 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 as communication channels.

Definition 2

The storage of information is understood as the operation of fixing a message on some physical medium. Paper and other surfaces, magnetic tape, laser disks, hard drives and other.

Remark 1

Information processing is understood as the operation of forming a new message from a set of existing ones. When processing information, there is a possibility of increasing its amount. The result of processing messages of one type can be the development of messages of another type.

Information transfer rate

Remark 2

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

But since the amount of information can also be measured in bytes, there is also a corresponding unit for measuring speed, bytes per second. For reference, one byte is eight bits. And, accordingly, 1 Byte / s = 8 bit / s. You should also pay attention to the fact that in the abbreviated format, a bit is written with a small letter (bits / sec), and a byte is written with a capital letter (B / sec). But since bits and bytes are 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, these attachments are:

• kilo (k), means that you need to multiply the number by a thousand (for example, one kilogram is a thousand grams).
• mega (M), means that you need to multiply the number by a million (curiously, this term was introduced relatively recently, in 1960).
• giga (G), means that the number needs to be multiplied by one billion (it is even more strange that this term originated back in 1947, that is, thirteen years earlier than the term mega).

In the electronic computing industry, binary 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).
• Mobi (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 decimal coefficients are usually used when determining the speed of information transmission. That is, one kbps corresponds to 1000 bps. 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 large letter B and, of course, one must remember that a byte contains eight bits.

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

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 into bytes, divide by eight.

For example, 100 Mbps = 100/8 = 12.5 Mbps.

Binary coefficients are not used very often to indicate the transmission rate of information. For example, 1 kibbit per second (1Kib / sec or 1Kib / s) = 1024 bit / sec. There is one danger here. Sometimes the use of binary coefficients is simply not indicated and there is a possibility that the symbol "M" does not mean "Mega", but "Mebi".

Internet speed

Since the advent of the Internet, the speed of data transmission in the network is measured in the number of bits per second. And the amount of data stored on a hard disk (or other medium), as a rule, is counted in bytes. Therefore, it should be remembered that when connecting to the Internet, in the proposed tariff plans the speed is indicated in Megabits per second, and with real data downloading software indicates the speed in MBs per second. That is, it is stated, for example, that the Internet speed will be 20 Mbit / s, but in reality we see 2.5 MB / s. But there is no catch here, it's just eight times the difference between a bit and a byte.

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

There are two types of connection - via cable, and over the air, wireless.

Cable connection.

In this case, there are least problems with numbers. The connection occurs at a speed of 10, 100 or 1000 megabits (1 gigabit) per second. This is not "internet speed", not the speed of opening pages or downloading files. It 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.

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 rest against this, and it is possible to achieve real 120 megabytes per second only in some cases.

The connection speed is selected automatically depending on how your connecting devices "agree", according to the slowest of them. If you have a gigabit Network Card(and now the majority of them are in computers), and from the other end there is 100 megabit equipment, then the connection speed will be set to 100mbit. No additional installations speed is not necessary, if it is required, this is an indicator that there is a problem with the cable, or with the equipment at you 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 for wireless connection the data transfer rate is about two times less than the standard figure says. How it looks in real data - see the table.

Standard	Frequency and bandwidth	Standard speed	Real file transfer rate	Additional Information
Wi-Fi 802.11 a	5Ghz. (20Mhz)	54 mbit / s		Currently, it is rarely used in household equipment, it is found in providers' networks.
Wi-Fi 802.11 b	2.4Ghz (20Mhz)	11 mbit / s	OK. 0.6 megabytes (4.8 megabits) per second	Currently only used for computer-to-computer communication (Ad-Hoc)
Wi-Fi 802.11 g	2.4Ghz (20Mhz)	54 mbit / s	OK. 3 megabytes (24 megabits) per second	So far, the most common type of connection.
Wi-Fi 802.11 n	2.4Ghz / 5Ghz (20Mhz / 40Mhz)	150, 300, 600 mbit / s	5-10 megabytes per second.	Conventionally, 1 stream (antenna) - 150 megabits, router (network) with 4 antennas supports 600mbps

As you can see, everything is very sad and ugly, and the vaunted “N” does not even come close to showing the numbers that I would like to see. In addition, this speed is ensured under near-ideal environmental conditions: no interference, no walls with metal between the router and the computer (better line of sight), and the shorter the distance, the better. In a typical three-room apartment reinforced concrete house a wireless access point installed in the back of the apartment can be almost elusive from the opposite side. The “N” standard provides the best 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 rate when using equipment with “G” is 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 is in the ranges, in some cases such a switch does not give a result.

The speed is also affected by the performance of the device that distributes the Internet (router, access point). With active use of torrents, for example, the speed of data transfer through the router can drop significantly - its processor simply cannot cope with the data stream.

The selected encryption type also affects the speed. From the very name it is clear that “encryption” is the processing of data in order to encode it. Different encryption methods can be used, and hence the performance of the device that this encryption-decryption performs is different. Therefore, it is recommended to set in the parameters wireless network WPA2 encryption type is the fastest and most secure on 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 spit on the standards.

One more point. In order to take full advantage of the N standard (especially for equipment supporting MIMO), the access point must be set to “N Only” mode.

If you choose “G + N Mixed” (any “mixed” mode), chances are high that your devices will not try to connect at maximum speed. This is the payment for standards interoperability. If your devices support “N”, forget about other modes - why lose the advantages offered? Using both G and N hardware on the same network 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 types of connection.

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

Units.

There is confusion caused by incorrect use of units. Probably, this is a topic for another article (on networks and connections, which I will write shortly), but still, here (compressed) it will be in place.

In the computer world, a binary number system is adopted. Smallest unit measurement - bit... Next is byte.

Ascending:

1 byte = 8 bits

1024 bits = 1 kilobits (kb)

8 kilobits = 1 kilobyte (KB)

128 kilobytes = 1 megabits (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 denoting the speeds of telecommunication connections, for example, 100 Mbit / s in the 100BASE-TX standard ("copper" Fast Ethernet) corresponds to the transmission speed of exactly 100,000,000 bit / s, and 10 Gbit / s in the 10GBASE-X (Ten Gigabit Ethernet) standard - 10,000,000,000 bit / s.

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

Different programs display the speed in different ways - some in kilobytes, some in kilobits. Formally, when we are talking about * bytes, a capital letter is put, about * bits-small (notation KB (KB, sometimes kB or KB, or KB)) - means “kilobyte”, kb (kb, or kbit) - “kilobit” , etc.), but this is not a fixed rule.

Think your broadband internet connection is fast? Beware, after reading this article, your attitude towards the word "fast" in relation to data transfer can change a lot. Imagine the volume of your hard disk on the computer and decide what speed it will fill up is fast -1 Gb / s or maybe 100 Gb / s, then 1 terabyte disk will fill up in 10 seconds? If the Guinness Book of Records established records for the speed of information transfer, then it would have to process all the experiments below.

At the end of the twentieth century, that is, still relatively recently, the speeds in the main communication channels did not exceed tens of Gbit / s. At the same time, Internet users using telephone lines and modems enjoyed speeds of tens of kilobits per second. The Internet was on cards and the prices for the service were rather big - tariffs, as a rule, were given in USD. It sometimes even took several hours to download one picture, and as one of the Internet users of that time accurately noted: "It was the Internet, when in one night you could only watch a few women on the Internet." Is this data transfer rate slow? Perhaps. However, it is worth remembering that everything in the world is relative. For example, if now it was 1839, then the world's longest optical telegraph communication line Petersburg-Warsaw would represent a kind of Internet for us. The length of this communication line for the nineteenth century seems simply transcendental - 1200 km, it consists of 150 relaying transit towers. Any citizen can use this line and send an "optical" telegram. The speed is "colossal" - 45 characters at a distance of 1200 km can be transmitted in just 22 minutes, no horse mail service was here and there!

Let's go back to the XXI century and see what we have today in comparison with the times described above. Minimum rates from large providers wired internet are calculated no longer in units, but in several tens of Mbit / s; we don't want to watch videos with a resolution of less than 480pi, this picture quality does not suit us anymore.

Let's see the average internet speed in different countries the world. The presented results were compiled by the CDN provider Akamai Technologies. As you can see, even in the Republic of Paraguay, already in 2015, the average connection speed in the country exceeded 1.5 Mbit / s (by the way, Paraguay has a domain that is close to us Russians in transliteration - * .py).

Today, the average speed of Internet connections in the world is 6.3 Mbps... The highest average speed is observed in South Korea - 28.6 Mbit / s, Norway is in second place - 23.5 Mbit / s, Sweden is in third - 22.5 Mbit / s. Below is a chart showing the average internet speed across the top-performing countries at the beginning of 2017.

Timeline of world records for data transfer rates

Since today fiber-optic transmission systems are the indisputable record holder in terms of range and transmission speed, the emphasis will be on them.

What speeds did it all start with? After numerous studies in the period from 1975 to 1980. the first commercial fiber-optic system appeared, operating with radiation at a wavelength of 0.8 microns on a semiconductor laser based on gallium arsenide.

On April 22, 1977, in Long Beach, California, General Telephone and Electronics first used optical fiber to carry telephone traffic at 6 Mbps... At this speed, it is possible to organize the simultaneous transmission of up to 94 of the simplest digital telephone channels.

Maximum speed optical transmission systems in experimental research facilities of this time reached 45 Mbps, the maximum distance between the regenerators is 10 km.

In the early 1980s, the transmission of a light signal took place in multimode fibers already at a wavelength of 1.3 μm using InGaAsP lasers. The maximum transfer rate was limited by the value 100 Mbps due to dispersion.

When using single-mode optical fibers in 1981, in laboratory tests, a record transmission rate for that time was achieved 2 Gbps on distance 44 km.

The commercial introduction of such systems in 1987 provided speeds up to 1.7 Gbps with the length of the route 50 km.

As you can see, it is worth assessing the record of a communication system not only in terms of transmission speed, it is also extremely important for what distance this system able to provide given speed... Therefore, to characterize communication systems, the product of the total system capacity B [bit / s] by its range L [km] is usually used.

In 2001, with the application of WDM technology, a transmission rate was achieved 10.92 Tbit / s(273 optical channels at 40 Gbps), but the transmission range was limited by the value 117 km(B ∙ L = 1278 Tbit / s ∙ km).

In the same year, an experiment was carried out to organize 300 channels with a speed of 11.6 Gbps each (total bandwidth 3.48 Tbit / s), the line length was over 7380 km(B ∙ L = 25 680 Tbit / s ∙ km).

In 2002, an intercontinental optical line with a length of 250,000 km with total bandwidth 2.56 Tbit / s(64 WDM channels at 10 Gbps, the transatlantic cable contained 4 pairs of fibers).

Now 3 million can be transmitted simultaneously with a single fiber! telephone signals or 90,000 television signals.

In 2006, the Nippon Telegraph and Telephone Corporation established a transmission rate of 14 trillion bits per second ( 14 Tbps) one by one optical fiber at line length 160 km(B ∙ L = 2240 Tbit / s ∙ km).

In this experiment, they publicly demonstrated the transmission of 140 digital HD films in one second. The value of 14 Tbit / s appeared as a result of combining 140 channels of 111 Gbit / s each. Wavelength division multiplexing and polarization multiplexing were used.

In 2009, Bell Labs achieved B ∙ L = 100 peta bits per second times kilometer, thus breaking the 100,000 Tbit / s ∙ km barrier.

To achieve such record results, researchers at Bell Labs in Villarceaux, France, used 155 lasers, each operating at a different frequency and transmitting data at 100 Gigabits per second. The transmission was carried out through a network of regenerators, the average distance between which was 90 km. Multiplexing 155 optical channels at 100 Gbit / s provided total bandwidth 15.5 Tbit / s on distance 7000 km... To comprehend the significance of this speed, imagine that data is being transferred from Yekaterinburg to Vladivostok at a speed of 400 DVDs per second.

In 2010 NTT Network Innovation Laboratories set a record for transmission speed 69.1 terabits per second one by one 240 km optical fiber. Using wavelength division multiplexing (WDM) technology, they multiplexed 432 streams (25 GHz frequency spacing) at 171 Gbps channel rates each.

In the experiment, coherent receivers, amplifiers with a low level of intrinsic noise and with ultra-broadband amplification in the C and extended L bands were used. In combination with QAM-16 modulation and polarization multiplexing, it turned out to achieve a spectral efficiency of 6.4 bps / Hz.

The graph below shows the trend in the development of fiber-optic communication systems over the 35 years since their inception.

From this graph, the question arises: "what next?" How can you increase the speed and transmission range by several times?

In 2011, the world record for throughput was set by NEC, transmitting more than 100 terabits of information per second over a single optical fiber. This amount of data transferred in 1 second is enough to watch HD movies continuously for three months. Or it is equivalent to transferring the contents of 250 double-sided Blu-ray discs per second.

101.7 terabits were transmitted in a second over a distance 165 kilometers by multiplexing 370 optical channels, each of which had a speed of 273 Gbit / s.

In the same year, the National Institute of Information and Communications Technology (Tokyo, Japan) announced the achievement of the 100 terab threshold of the transmission rate through the use of multi-core optical fibers. Instead of using fiber with only one light-guiding strand, as is the case with modern commercial networks, the team used seven-core fiber. Each of them was transmitted at a speed of 15.6 Tbit / s, thus, the total throughput reached 109 terabits per second.

As the researchers said at the time, the use of multicore fibers is still a rather complicated process. They have high attenuation and are critical to mutual interference, therefore they are strongly limited in transmission range. The first application of such 100 terabit systems will be inside the giant data centers of Google, Facebook and Amazon.

In 2011, a team of scientists from Germany from the Karlsruhe Institute of Technology (KIT), without using xWDM technology, transmitted data over one OF at a speed 26 terabits per second per distance 50 km... This is the equivalent of 700 DVDs per second or 400 million phone signals simultaneously on one channel.

New services such as cloud computing, high-definition 3D television and virtual reality applications began to emerge, again requiring unprecedented high optical capacity. To solve this problem, researchers from Germany demonstrated the use of an optical FFT scheme for encoding and transmitting data streams at a rate of 26.0 Tbit / s. To organize such a high transmission rate, not just the classical xWDM technology was used, but optical multiplexing with orthogonal frequency division multiplexing (OFDM) and, accordingly, decoding of optical OFDM streams.

In 2012, Japan's NTT (Nippon Telegraph and Telephone Corporation) and its three partners, Fujikura Ltd., Hokkaido University and the Technical University of Denmark, set a world bandwidth record by passing 1000 terabit (1 Pbit/ with) information per second over one optical fiber at a distance 52.4 km... Transferring one petabit per second is equivalent to transferring 5000 two-hour HD movies per second.

With the aim of significantly improving the throughput of optical communication systems, a fiber with 12 cores, arranged in a special way in the form of a honeycomb, was developed and tested. In this fiber, due to its special design, mutual interference between adjacent cores, which is usually the main problem in conventional multi-core optical fiber, is significantly suppressed. As a result of the application of polarization multiplexing, xWDM technology, 32-QAM and digital coherent reception, scientists have successfully increased the transmission efficiency per core by more than 4 times, compared to previous records for multi-core optical fibers.

The throughput was 84.5 terabits per second per core (channel speed 380 Gbit / s x 222 channels). The total throughput per fiber was 1.01 petabits per second (12 x 84.5 terabits).

Also in 2012, a little later, researchers from the NEC Laboratory in Princeton, New Jersey, USA, and New York Research Center Corning Inc., successfully demonstrated ultra-high data transfer rates at 1.05 petabits per second. Data was transmitted using one multi-core fiber, which consisted of 12 single-mode and 2 low-mode cores.

This fiber was developed by the Corning researchers. By combining spatial multiplexing and optical MIMO technologies, and using multi-level modulation formats, the researchers achieved a total throughput of 1.05 Pbps, thus setting a new world record for the fastest transmission rate over a single fiber.

Summer 2014 working group in Denmark, using a new fiber offered by the Japanese company Telekom NTT, set a new record - organizing with a single laser source the speed at 43 Tbit / s... The signal from one laser source was transmitted over a seven-core fiber.

The Danish Technical University team, together with NTT and Fujikura, have previously achieved the world's highest data transfer rate of 1 petabits per second. However, then hundreds of lasers were used. Now, the 43 Tbit / s record has been achieved with a single laser transmitter, making the transmission system more energy efficient.

As we have seen, the connection has its own interesting world records. For those new to this field, it is worth noting that many of the figures presented are still not found everywhere in commercial operation, since they were achieved in scientific laboratories in single experimental installations. However, cellular telephone was once a prototype.

In order not to overload your storage medium, while we stop the current data flow.

To be continued…

The rate of data transmission over a communication channel is measured by the number of bits of information transmitted per unit of time - a second.

The unit of measurement for the data transfer rate is bits per second.

Note. A commonly used unit of measure for speed is baud. Baud is the number of changes in the state of the transmission medium per second. Since each state change can correspond to several bits of data, then real speed bits per second can exceed the baud rate.

The data transfer rate depends on the type and quality of the communication channel, the type of modems used and the accepted way synchronization.

So, for asynchronous modems and a telephone communication channel, the range of speeds is 300-9600 bit / s, and for synchronous modems - 1200-19200 bit / s.

For users computer networks what matters is not the abstract bits per second, but the information, the unit of which is bytes or characters. Therefore, a more convenient characteristic of a channel is its throughput, which is estimated by the number of characters transmitted over the channel per unit of time - a second. In this case, all service symbols are included in the message. The theoretical bandwidth is determined by the data transfer rate. The actual bandwidth depends on a number of factors, including the transmission method, and the quality of the communication channel, and the conditions of its operation, and the structure of messages.

The unit of measurement of the communication channel throughput is a character per second.

An essential characteristic of the communication system of any network is the reliability of the information transmitted. Since, on the basis of processing information about the state of the control object, decisions are made about a particular course of the process, then the fate of the object may ultimately depend on the reliability of the information. The fidelity of information transmission is assessed as the ratio of the number of erroneously transmitted characters to the total number of transmitted characters. The required level of confidence should be provided by both the hardware and the communication channel. It is unreasonable to use expensive equipment if the communication channel does not meet the necessary requirements with respect to the level of reliability.

Validity unit: number of errors per sign - errors / sign.

For computer networks, this indicator should be in the range of 10-6 -10-7 errors / sign, i.e. one error per million characters transmitted or ten million characters transmitted is allowed.

Finally, the reliability of a communication system is determined either by the fraction of uptime in the total operating time, or by the average uptime. The second characteristic allows you to more effectively assess the reliability of the system.

Reliability unit: MTBF - hour.

For computer networks, the MTBF should be large enough and be at least several thousand hours.

The data transfer rate characterizes the amount of data that is transferred over a specific period of time. You need to know the transmission speed if you download something from the Internet or copy data from one storage medium to another. First, you need to convert the units of the file size and transfer rate so as to unify them, and then substitute the values ​​into the formula S = A ÷ T, where A is the data volume, T is the transfer time, S is the transfer rate. Also, using this formula, you can calculate the amount of data or the transfer time, if you know one of the variables and the transfer rate.

Steps

Part 1

Unit Conversion

Find the units of measure for the file size. The file size can be specified in bits (bits), bytes (B), kilobytes (KB), megabytes (MB), gigabytes (GB), and even terabytes (TB).

• Pay attention to uppercase and lowercase letters. For example, a bit is denoted as "bit" (in lowercase letters), and a byte is capital letter"B"

1. Pay attention to the units of measurement of the baud rate. Transfer rates can be expressed in bits per second (bps), bytes per second (B / s), kilobytes per second (KB / s), megabytes per second (MB / s), or gigabytes per second (GB / s).

2. Convert units to bits or bytes and make sure they have the same prefix (K, M, G). Before using the formula, make sure you have the same file size and bit rate units. Don't think about time units.

   • 8 bits = 1 byte (B); to convert bits to bytes, divide the value in bits by 8. To convert bytes to bits, multiply the value in bytes by 8.
   • 1,024 bytes = 1 kilobyte (KB); to convert bytes to kilobytes, divide the value in bytes by 1024. To convert from kilobytes to bytes, multiply the value in kilobytes by 1024.
   • 1,024 kilobytes = 1 megabyte (MB); to convert kilobytes to megabytes, divide the value in kilobytes by 1024. To convert from megabytes to kilobytes, multiply the value in megabytes by 1024.
   • 1,024 megabytes = 1 gigabyte (GB); to convert megabytes to gigabytes, divide megabytes by 1024. To convert gigabytes to megabytes, multiply gigabytes by 1024.
   • 1,024 gigabytes = 1 terabyte (TB) to convert gigabytes to terabytes, divide gigabytes by 1024. To convert terabytes to gigabytes, multiply terabytes by 1024.

3. Convert time units if necessary. In 1 minute 60 seconds, and in 1 hour 60 minutes. To convert seconds to minutes, divide seconds by 60. To convert minutes to hours, divide minutes by 60. To convert hours to minutes, multiply hours by 60. To convert minutes to seconds, multiply minutes by 60.

   • To convert seconds to hours, divide by 3600 (60 x 60). To convert hours to seconds, multiply by 3600.
   • Typically, the baud rate is indicated in seconds. If the transfer of a large file took too many seconds, convert them to minutes or even hours.

   Part 2

   Calculation of baud rate, time and data volume

   1. Calculate the transfer rate by dividing the amount of data by the transfer time. Plug in the data volume (A) and transmission time (T) values ​​into the formula S = A ÷ T.

      • For example, a 25 MB file is transferred in 2 minutes. First convert 2 minutes to seconds: 2 x 60 = 120 seconds. So S = 25 MB ÷ 120 s = 0.208. Therefore, the transfer rate is 0.208 MB / s. To convert this value to kilobytes, multiply 0.208 by 1024: 0.208 x 1024 = 212.9. So the transfer rate is also 212.9 KB / s.

   2. Calculate the transfer time by dividing the amount of data by the transfer rate. That is, use the formula T = A ÷ S, where T is the transfer time, A is the amount of data, S is the transfer rate.

      • For example, a 134 GB file was transferred at 7 MB / s. First, convert GB to MB to unify the units: 134 x 1024 = 137217 MB. So, 137,217 MB were transferred at 7 MB / s. To find the transmission time (T), divide 137217 by 7 to get 19602 seconds. To convert seconds to hours, divide 19602 by 3600 to get 5.445 hours. In other words, it took 5.445 hours to transfer 134 GB of data at 7 MB / s.
      • To use hours and minutes, separate the whole and fractional parts of the decimal. In our example, this is 5 hours and 0.445 hours. To convert 0.445 hours to minutes, multiply by 60: 0.445 x 60 = 26.7 (26 minutes and 0.7 minutes). To convert a decimal to a second, multiply by 60: 0.7 x 60 = 42. So the transfer time was 5 hours 26 minutes and 42 seconds.

   3. Calculate the amount of data by multiplying the transfer time by the transfer rate. That is, use the formula A = T x S, where T is the transfer time, A is the amount of data, S is the transfer rate.

      • For example, you need to determine how much data was transferred in 1.5 hours at a speed of 200 bps. First, convert hours to seconds: 1.5 x 3600 = 5400 s. So A = 5,400 s x 200 bps = 1,080,000 bps. To convert this value to bytes, divide by 8: 1080000 ÷ 8 = 135000. To convert the value to kilobytes, divide by 1024: 135000 ÷ 1024 = 131.84. Thus, 131.84 KB of data was transferred in 1.5 hours at 200 bps.