- Binary Numbers
- HD image quality
- Base station
- Infrastructure deployment rate
- Ultraviolet rays
- Frequency band
- Population coverage
- World Health Organization (WHO)
- Infrared rays
- Ministry of Internal Affairs and Communications
- Electromagnetic waves
- Radio Law
- Radio wave protection guidelines
- Optical fiber
- Extremely high frequency
- Morse code
Binary numbers are a way to display numbers using only 0 and 1. This system is used among computers because it is much simpler to build a machine that automatically calculates in binary numbers than in decimal numbers. For example, if you want to add one digit in binary, you need to make sure that the machine can handle 4 different rules (2 x 2 = 4), such as displaying 1 in the tenth place for 1 + 1 and 0 in the first place. If this is a decimal number, the machine must be able to perform 10×10=100 calculations.
An image with a resolution of around 4,000px (width) x 2,000px (height). Full HD" images, which have been the most common in recent years, have a resolution of 1,920px (width) × 1,080px (height), so 4K has about four times the resolution. In recent years, consumer-use digital cameras and smartphones that can take 4K images have been sold, and it is expected to become even more popular in the future. Incidentally, 8K has a resolution of 8000px wide x 4000px high, four times that of 4K.
In radio broadcasting, there are two main methods of putting sound on the airwaves: AM and FM.
AM is a modulation method called "Amplitude Modulation" and has been used since the beginning of radio broadcasting. It has a wider range of radio waves, but is more prone to noise.
FM is a modulation method called "Frequency Modulation," and has been used in Japan since around 1970. The range of radio waves is narrow, but it is characterized by low noise and good sound quality.
HD image quality
This refers to video with a resolution of around 1280px (width) x 720px (height). This image quality is mainly used in video services such as YouTube. The order of resolution is SD < HD < Full HD < 4K < 8K. Incidentally, SD quality is used for DVDs and analog broadcasts, Full HD is used for BluRay, and 4K and 8K are used for BS and some YouTube services.
A function that allows users to send and receive e-mails and browse web pages on cell phones (galakeyas). i-mode was launched by NTT DoCoMo in 1999, and was a revolutionary function at the time, and exploded in popularity. The service is scheduled to be terminated on March 31, 2026.
LTE is an abbreviation for Long Term Evolution, a standard used to "evolve" from 3G to 4G in order to facilitate the transition from 3G to 4G. It is sometimes called 3.9G because it was a bridge between 3G and 4G.
A wireless communication standard for smartphones and cell phones, LTE-Advanced is the "evolution" of LTE and is a legitimate 4G communication standard. Carrier aggregation was first introduced here.
An online site in the United States that provides factual verification of fake news and urban legends.
A general term for radio waves with frequencies below 6 GHz. It has a much lower frequency than millimeter waves, so it can deliver radio waves over a wider area, but it is inferior to millimeter waves in terms of communication speed.
One of the video sharing sites provided by Google. Basically, anyone with a Google account can post videos for free. In recent years, 4K videos and 360° videos have been added, allowing you to watch a wide variety of videos.
Wi-Fi is a communication standard designed to connect wirelessly to devices that cannot be wired to fixed lines such as fiber-optic lines in homes and offices. It uses frequencies in the 2.4GHz and 5GHz bands. Currently, IEEE 802.11ac (Wi-Fi 5) is the mainstream standard, and the latest standard IEEE 802.11ax (Wi-Fi 6) also exists. It is expected that Wi-Fi will be replaced by 5G in the future.
A facility that converts Internet and other data into radio waves and transmits them to smartphones and other devices. Cell phone companies such as Docomo, KDDI, Softbank, and Rakuten Mobile have their own base stations. Each company has installed base stations all over Japan, and the total number of base stations is about one million*. There are various types of base stations, including towers, those built on the rooftops of buildings, and small ones installed on utility poles. If you know which base station you are communicating with, you can determine the approximate location without using GPS.※Total number of 3G, 4G, and BWA base stations in Japan as of November 2019 総務省総合通信基盤局.携帯電話及び全国BWAに係る電波の利用状況調査の評価結果の概要（案）（参照 2020-11-15https://www.soumu.go.jp/main_content/000654166.pdf
Infrastructure deployment rate
An index showing the percentage of areas where base stations (parent units), which will be the core of 5G communications, have been installed out of about 4,500 areas, excluding uninhabited areas such as areas over the sea or deep in the mountains, by dividing the whole of Japan into a 10 km square mesh. When the Ministry of Internal Affairs and Communications allocated 5G frequencies to companies, it asked them to aim for a deployment rate of 50% or more within five years.
A type of electromagnetic radiation. The frequency is higher than that of visible light and lower than that of X-rays. If humans are exposed to ultraviolet rays contained in sunlight for a long period of time, it can cause diseases such as skin cancer and cataracts. Measures to protect oneself from UV rays include wearing UV-protective sunscreen and sunglasses.
The range of frequencies of radio waves is called the frequency band. The wider the range, the more data can be sent.
It is an index used to indicate the coverage of 4G in Japan since 2014. Suppose to divide the entire land of Japan into a 500 meter square mesh, it shows the percentage of meshes that have been covered nationwide, based on the standard that if communication is possible in more than 50% of the area of one mesh, then that area has been covered.
A term used to describe the size of a wave. The amplitude of a wave. The higher the amplitude of a sound wave, the louder the sound. The unit of volume, decibel (dB), is the normal logarithm of amplitude.
World Health Organization (WHO)（WHO）
One of the specialized agencies of the United Nations. The World Health Organization (WHO) is one of the specialized agencies of the United Nations. Its mission is "to achieve the highest possible standard of health for all people," and its activities include the collection and dissemination of health-related information and the control of infectious diseases.
One of the electromagnetic waves. Its frequency is higher than that of radio waves, but lower than that of visible light. It is used for communications such as TV remote controls, as well as for technologies that capture three-dimensional shapes, such as iPhone Face ID.
Ministry of Internal Affairs and Communications
One of Japan's administrative agencies. The Ministry of Internal Affairs and Communications (MIC) manages the basic systems that support Japanese society, including administrative management, information and communications, and fire and disaster management. The Telecommunications Bureau within the Ministry of Internal Affairs and Communications is in charge of promoting 5G and allocating frequencies.
A wave in which changes in the electric and magnetic fields are transmitted in a chain reaction. Radio waves, light, and radiation are all included in electromagnetic waves, which are classified according to their frequency. All electromagnetic waves travel at a speed of 299,792,458 m/s (about 300,000 km/s).
A Japanese law for the fair use of radio waves. Depending on the purpose of use of radio waves, the standards of devices that can be used, frequency, strength of radio waves, and whether or not a license is required are stipulated. All of the communication devices we use, such as smartphones, are certified by the government based on this Radio Law.
You can check the certification mark for "Technical Regulations Conformity Certification" based on the Radio Law from the settings of your smartphone.
- For iOS: Settings > General > Legal Information and Certifications > Legal Certificates
- For Android: Settings > Device Info > Certification Information
Radio wave protection guidelines
The Ministry of Internal Affairs and Communications has established standards for the safety of radio waves to the human body. It sets standards for radio wave output in consideration of the "stimulating" and "thermal" effects of radio waves on the human body. In addition, based on the emergence of 5G, the standards were revised for high frequencies (6 GHz to 300 GHz) in 2018. The content may be revised in the future if adverse effects of radio waves on the human body other than stimulation and thermal effects are scientifically proven.
The length of a single wave. It is inversely proportional to frequency. In other words, the higher the frequency, the shorter the wavelength, and the lower the frequency, the longer the wavelength. For your information, the wavelength of millimeter wave used in 5G is about 10 mm.
One of the electromagnetic waves. Generally speaking, it is a general term for the three types of electromagnetic waves: ultraviolet, visible, and infrared. Light has the characteristics of a wave, and depending on its frequency, our eyes perceive it as light of different colors.
An artificial fiber made of glass or other materials. It is a technology used to transmit light to distant locations and is used for wired communication. By using a material with a large refractive index in the center and a smaller one in the periphery, light travels through the fiber with total reflection even if it is bent a little. Communication using optical fiber is called "optical fiber line". A laser beam is passed through the optical fiber, and information is transmitted by the flickering of the beam. The communication speed of optical fiber lines is up to 1 Gbps, which is generally considered faster than other wired lines and 4G. However, 5G is capable of communicating at a maximum of 10 to 20 Gbps, which is much faster than the communication speed of optical lines.
The conversion of information into electrical signals when transmitting data. Modulation can be broadly divided into "analog modulation" and "digital modulation. Analog modulation is a method of converting continuous waveforms such as sound directly into radio wave forms. Digital modulation is a method of transmitting two signals, "0" and "1", on a radio wave.
Extremely high frequency
A radio wave with a frequency between 30 and 300 GHz, called Extremely high frequency because the wavelength of radio waves at frequencies above 30 GHz is lower than 1 cm. The higher frequency is called Extremely high frequency, and while Extremely high frequency enables faster communication than Sub-6 and 4G, it has the disadvantage of not being able to reach as far and being easily blocked by obstacles and rain.
A family of birds in the order Sparrowhawks. Many species live in flocks and feed on fruits and insects. They inhabit a wide range of habitats around the world. The "starling" often seen in Japan is a species in the starling family. The Japanese starling is about 24 cm long* and is characterized by its yellow beak.※石戸忠,今泉忠明「日本の生き物図鑑」講談社、2008年4月。
One of the character codes used in telegraphs. It has been in use since the 19th century, but gradually fell out of use in the latter half of the 20th century with the spread of digital communication. It has been in use since the 19th century, but gradually fell out of use in the late 20th century due to the spread of digital communication, but is still used in Japan by the Self-Defense Forces and in amateur radio. In "Ponyo on the Cliff by the Sea", there is a scene where Sosuke (age 5) uses Morse code to communicate with his father's boat using a signal light. A five-year-old who has mastered Morse code... How terrifying...