The Use of Light as a Communication Media: China Great Wall

The use of light as a communication medium in the Great Wall is more than 7,300 kilometers apart and sends a signal from one tower to another within one hour. In the latter half of the 20th century, optical communication returned to the seat, taking advantage of coaxial transmission and other telecommunication systems. In 1966, Kaw and Hockman proposed the idea of ​​using fiber optic lightwave communication, and their prediction was a data loss of 20 dB / km [12]. From the late 1980's to the 1990's, a coherent detection communication system was introduced to enhance the transmission system.

The Great Wall of China: The Great Wall of China was built by Qin Shihuang about 2000 years ago. The famous walls were built between 220 BC and 206 BC. The aim of the Great Wall was to protect the Chinese empire from the invasion of nomads tribes and troops. The length of the wall is about 5000 kilometers, and the height is 7.5 meters. In the late Ming dynasty, the Great Wall expanded to 6,400 kilometers. Forbidden City: Forbidden City is located in the center of Beijing. This is the palace of 24 emperors during the Ming and Qing era. It was built in the year 1406 - 1420, the ancient Chinese astronomer thought that purple star (Hokusai) is in the center of the heaven, so the emperor lived in the purple palace.

Now, I know the Great Wall of China. Emperor Qin Shihuang was the first emperor to unite China. In the past few years and 202 BC the wall declined and rose. Han Taka who became the emperor at that time ordered to strengthen the Great Wall. Later, as Silk Road trade provided valuable export opportunities and economic value, it expanded further to protect the Silk Road. During the Ming dynasty, the Great Wall continued to improve and recover, leading to the Great Wall of the Day today. The main influence of this is the threat of Japanese pirates, and Ji Jiguang believes that strengthening the wall is the best form of this threat.

Did the Great Wall really truly succeeded in placing enemies outside China? Short answer: Yes, the Great Wall successfully blocked the semi-nomadic intruder, which is the greatest concern at the time. However, the walls could not prevent large intrusions, even nomads could sometimes break through the wall. Early in the 7th century BC some walls began to be constructed but the first emperor Qin Shihuang connected these parts and made something similar to the wall between 221 BC and 206 BC . This is like a series of guard posts that will help warn the intrusion and spread the signal to attract reinforcements.