Secrets of Submarine Cables - Transmitting 99 percent of all international data!
- KogaIn the past, communications satellites were mostly used. But, since the advent of optical fibers capable of transmitting large volumes of data with little latency, submarine cables have come to be used instead in most cases. It is said that submarine cables now account for more than 99 percent of international communications.
- MitaMore than 99 percent! Almost all of our international data communications are via a submarine cables! That means unimaginably huge amounts of data come and go through the submarine cable, right?
- KogaYes. Certainly, enormous volumes of data travel back and forth. But the submarine cable is a fiber-optic communication, which enables a massive amount of data to be exchanged instantly. You mentioned communication by satellite just now. So let's compare submarine cable communication with that.
- MitaThat would be great.
- KogaThe circumference of the earth is said to be about 40,000 kilometers. And the ground distance between Japan and the U.S., for example, is 9,000 kilometers. In comparison, a communications satellite on a geostationary satellite orbit is 36,000 kilometers above the earth's surface. A signal needs to travel about 72,000 kilometers just to make a round trip to the communications satellite and back. Now, which is the shorter way to connect two destinations, by submarine cable or by satellite?
- MitaSubmarine cable.
- KogaThat's right. Also, data communication via a communications satellite is susceptible to weather conditions, like rain or typhoons, while submarine cables are not affected by the weather. So there are two advantages that the submarine cable has over the communications satellite: shorter communication distance and insusceptibility to weather conditions.
- MitaThat means the submarine cable is a more secure and more reliable infrastructure capable of sending data with less latency.
- KogaThat's right. And the biggest difference is the amount of data that can be transmitted. An optical fiber used in the latest type of submarine cable can send 3,840 gigabits of data per second. This means an amount of data equivalent to 102 DVDs is delivered in a second (the capacity of a single DVD being 4.7 gigabytes or 37.6 gigabits). With communication via a communications satellite, however, you cannot send even one DVD's worth of data. The communications capacity of the submarine cable is more than 1,000 times greater than that of a communications satellite.
- MitaIs it that different?
- KogaYes. So communication via a submarine cable is overwhelmingly faster than via a communications satellite.
- MitaWow, that's impressive. Submarine cables are amazing, aren't they? But wait a minute. Japan has a population of 120 million. The total population of the world is seven billion. I wonder if "102 DVDs worth of data per second" is enough.
- KogaActually, a submarine cable can send a lot more data.
- MitaWhat do you mean?
- KogaA submarine cable can send 3,480 gigabits of data per second per optical fiber. And a single submarine cable has up to eight pairs of optical fibers in it. To use an analogy, there are many traffic lanes in a submarine cable for data to travel, and that makes it possible to transmit a huge amount of data at once. We have several such transpacific submarine cables between Japan and the U.S. alone.
- MitaI see. It's like having several multi-lane expressways between Japan and the U.S., am I right?
- KogaSomething like that. And, thanks to advances in technology, the amount of data that an optical fiber can transmit keeps increasing at a fast pace.
- MitaCould you be more specific?
- KogaSome of the latest submarine cables can send up to 64 terabits of data per second.
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