Recently, a comment asked me
the difference between Bluetooth and Wi-Fi. If you ask what's the difference between Bluetooth and Wi-Fi,
it's probably better to answer. But everyone!
Did you know that Wi-Fi was developed while studying black holes? This story goes back to 1974. You all know British physicist Stephen Hawking. Stephen Hawking has published a theory that says, "Mini black holes, which are heavier than Mount Everest,
but smaller than atoms, can exist." And he said that
these small black holes could only be made in the 'big bang' process, and he predicted that under certain conditions,
mini black holes would evaporate or explode and emit radio signals. If the signal could be observed, it would be important evidence of the process of the creation of the universe. So, many scientists jumped into the study. Dr. John O'Sullivan, an Australian radio astronomer and electronic engineer,
was one of them. Dr. O'Sullivan devised a method to find black hole signals
by dividing them into multiple frequency components and filtering out noise and distorted signals in a particular frequency band
in order to eliminate the noise of a very weak radio signal from a mini black hole reaching us. However, the observation of the mini black hole failed. Even if there is a mini black hole,
the radio telescope is too small to detect the radio signals that the mini black hole makes. But! Dr. O'Sullivan thinks, 'Can we use this technology in real life?' In the 1980s, many telecommunications companies tried
to develop wireless communication technology, but they were struggling
because they could not solve the distortion of the original signal due to the reflection of radio waves on surfaces such as furniture and walls. But Dr. O'Sullivan tried to transmit large data in a single radio signal,
rather than in a single radio signal, and then divide it into several small signals,
replicate it several times and transmit it in parallel. Because small signals were replicated several times with relatively less interference, the probability of reaching the destination also increased,
allowing large amounts of data to be transmitted efficiently. At the destination, we implemented a technology to recombine the original signal
by quickly connecting and synchronizing incoming signals divided into several. This technology is the Wi-Fi we are using today. More than 5 billion wireless LAN devices used by humans use
Dr. O'Sullivan's patents, and the Australian Federal Academy of Sciences, to which he belongs,
has earned more than $500 million, in Wi-Fi patent fees so far. And much of that income is reinvested in funds for future research
by the Australian Federal Academy of Sciences, leading to another innovation in science and technology. In this case, we can see why investing in basic science is important. For more information, in the "90 Night Universe"
published by the Korea Astronomy and Space Research Institute You can check it out. Once again, to summarize the principle of Wi-Fi, you need to have an AP,
a wireless access device that we usually call a "router." When you install a router,
it converts Internet signals flowing on wired Internet lines into wireless signals and spreads them to the surrounding space. Wireless communication devices can use this radio wave
to send and receive data and access the Internet. It uses frequencies in the 2.4 GHz and 5 GHz bands. This frequency affects the amount of data that can be transmitted,
the rate of transmission, and the distance. At 2.4 GHz, 13 channels exist at 5 MHz intervals. There are many overlapping sections between channels,
which affect the channels and cause a decrease in transmission speed. So 2.4GHz is slow at up to 100 megabits per second,
but it has a long wavelength, allowing data to be transmitted over long distances. At 5 GHz, there are 24 channels at intervals of 20 MHz. Relatively few overlapping channels allow
for faster speeds of up to 1G gigabit per second, but the higher the frequency, the shorter the wavelength,
reducing the diffraction capacity, so the transmission range is narrower than 2.4GHz. That's why closing the door weakens the Wi-Fi signal. So what's the difference between Bluetooth? First of all, I wonder why it's Bluetooth. It turned out that Ericsson, a Swedish telecommunications equipment company
that developed Bluetooth technology for the first time, hoping that wireless technology standards would be unified with their technology, took it from the nickname of the king of
Denmark and Norway, Harald Blotan Gormson, who unified Scandinavia around the 10th century, There is a theory that Haral I's nickname was Bluetooth
because he liked blueberries and his teeth were always blue. The Bluetooth symbol was also created
by combining the Scandinavian rune characters for Haral's H and Bluetooth's B. Anyway, Erickson's dream seems to have come true. Bluetooth, like Wi-Fi, also uses frequencies to exchange data between devices. But the frequency band you use is different. When Wi-Fi used the 2.5 GHz and 5 GHz bands,
Bluetooth uses 79 channels ranging from 2402 to 2480 MHz. Because Bluetooth uses the same frequency band,
radio interference may occur with each other, and 'frequency hopping' is used to prevent this. Frequency hopping is a technique
that moves a large number of channels quickly according to a specific pattern and transmits packets little by little. It is said to hoop 1600 times per second for 79 allocated channels. This hopping pattern must be synchronized
between the devices so that communication can take place. Bluetooth devices are divided into master and slave,
and when the smartphone is linked with the vehicle, the smartphone becomes the master device
and the vehicle becomes the slave device. One master device can connect up to seven slave devices. On the other hand, Wi-Fi does not have a limited number of connected devices,
but it slows down as many devices connect. This is also the reason why Wi-Fi is not working well
in crowded places such as public transportation. However, research is also being conducted
to overcome these limitations. ETRI, the state-run Electronics and Telecommunications Research Institute, has developed a technology
that enables high-speed Wi-Fi service on buses running on the road. It is said that you can enjoy ultra-high-definition video, VR, and AR contents
without interruption by using the 5G millimeter wave frequency in the 22GHz band. So what is the principle of airdrop? Airdrops use both Bluetooth and Wi-Fi technologies. First, you discover devices you want to share
via Bluetooth and share the Wi-Fi encryption key between devices you want to connect to create a peer-to-peer Wi-Fi network. After that, when you share files,
you send and receive files using Wi-Fi. At this time, it is faster than Bluetooth by using Wi-Fi Direct, which can configure a wireless network
between devices without a separate intermediary device. It is said that the Galaxy's quick share works on the same principle. When I traveled abroad,
a foreigner said he would take a picture of me, so I was thinking, "How do I get the picture?"
but when I saw him send me an airdrop, I thought, "It's become so good in the world." I thought that science and technology make the world really good If this video helped you to know a little
about the principles of Wi-Fi, Bluetooth, and AirDrop, press subscribe, like, and comment if you have any science and technology
you are curious about. I'll study so that you can know one day. Science and technology change the world.
As always.
