Soon after Xia Xue and Li Shimin got married, Xia Xue, who attached great importance to maritime strategy, suggested that Li Shimin build several important seaports in the north: Tianjin Port, Qingdao Port, etc., and originally wanted to build Dalian Port, etc., but suddenly thought that the current Dalian was still in the hands of Goguryeo, so he could only wait for later.

She also suggested that near Huating County in the south, according to the latest technology of the Angel Kingdom, build a super international city, and she named this future city: Haijing, and made it the southern capital of the Tang Empire.

Xia Xue knows the potential and influence of Haijing in the future, as a part of the alluvial plain of the Yangtze River Delta, the confluence of the Yangtze River and the Huangpu River, the Yangtze River in the north, the East China Sea in the east, Hangzhou Bay in the south, and Suwu and Zhejiang in the west.

Xia Xue believes that through continuous construction and development, Haijing will become the center of the north and south coasts of Datang, a super world port city, a central city of maritime and water transportation, a super economic, cultural and governance center of the world, and the most brilliant Oriental Pearl.

Moreover, Haijing has a subtropical monsoon climate, with four distinct seasons, sufficient sunshine, abundant rainfall, and a mild and humid climate. It is more suitable to become a megacity with a population of more than 10 million, which is not suitable for building a megacity with a population of more than 10 million due to its relatively arid nature and insufficient rainwater and fresh water resources.

For Xia Xue, Li Shimin has always had absolute trust, and he knew that her suggestions must have long-term significance, so he naturally agreed to them all, and the construction of these seaports and cities immediately started.

In order to promote the construction of the northern seaport, Xia Xue introduced the advanced technology of the Angel Kingdom in the north, and built many large-scale steel mills, steel casting and forging plants, cement factories, thermal power plants, machinery manufacturing plants, shipyards, etc., and brought new technologies such as steam engines, internal combustion engines, and electric motors to the north of the Tang Dynasty, which opened the eyes of many Tang Dynasty ministers and amazed them. Of course, there are also some very conservative veterans who say that these new technologies are ingenious, playthings, and useless.

Regarding the attacks of these corrupt old ministers, Tang Taizong Li Shimin and the eldest grandson Empress Xia Xue just smiled slightly and ignored them, what should they do. They know that if it weren't for these "miraculous skills", it is estimated that Datang would still be living and groveling under the power of the Turks.

Thinking that when he lured the enemy in Yinshan, Li Shimin was so anxious that a few gray hairs grew on his young head, and his face was full of anxiety and haggardness, Xia Xue felt distressed. I think that the ancient backward communication technology should indeed be changed.

During the Sui and Tang dynasties, the main methods of long-distance communication included: post delivery, carrier pigeons, and beacon smoke.

The courier is a person who is in charge of carrying the letter to the destination on horseback. Setting up a reliable and fast post system is very costly, starting with a good road network and then equipping it with the right post facilities. It is even more infeasible in areas with limited access.

The use of carrier pigeons for communication is very unreliable and is limited by weather and routes.

Another type of communication method is to use signals that are visible to the naked eye, such as beacon smoke or swing-arm signals, to transmit the communication by relay method. This method is also costly and susceptible to weather and terrain formation.

Therefore, during the Sui and Tang dynasties and the entire ancient community, only the most important news would be transmitted, and the transmission speed was unbearably slow in Xia Xue's opinion.

Xia Xue used her profound knowledge of physics and chemistry and mechanical manufacturing ability, and after more than five months of research, she finally succeeded in developing a wireless telegraph transceiver. Wireless electromagnetic waves are used as carriers to transmit and exchange information over long distances through coding and corresponding electrical processing technologies. To this end, she also wrote the Morse code.

The wireless telegraph transceiver developed by Xia Xue can transmit and receive electromagnetic radio waves through antennas. The electric key is used to control the oscillation of a low-frequency signal generator, and then it is modulated by a high-frequency carrier signal, amplified by power, and transmitted by the antenna, and its working frequency point is set in the short-wave band; At the receiving end, after receiving the radio signal, the receiving antenna selects, converts, amplifies and amplifies the low-frequency signal through the detection, and obtains the arrangement information of the low-frequency signal with and without composition, which is decoded by the telegrapher.

The composition of its code Xia Xue completely borrowed from Morse code, composed of five audio signals of different lengths to form 0-9 ten numbers and 26 English letters, composed of radio telegraph transmission and reception communication system, because of the simplicity of this communication equipment, the communication distance can reach more than 1,000 kilometers, once invented, it shocked Li Shimin and the ministers. The message can be transmitted thousands of kilometers in one day, that is, let the fastest horse run, it is estimated that it will take about ten days to deliver the message, if the horse is average, and the road is difficult, it is estimated that the time will be longer.

The advantage of ancient times is that all kinds of electromagnetic interference are very small, so the wireless telegraph transceiver developed by Xia Xue does not need to be too long and too large to receive the antenna, nor does it need a large transmitting power, so the volume is not large, and one person can run on his back, which is very suitable for military communication. If a number of signal transfer stations are established in suitable locations across the country, then staying in Chang'an can grasp the latest situation in various places in the vast Tang Dynasty in the shortest possible time, so that Tang Taizong Li Shimin, Xia Xue, and the ministers can make decisions in the shortest possible time and give feedback to the local implementation, so the work efficiency will be greatly improved. In particular, in the event of a sudden disaster or war, we can also know about it in the shortest possible time and make deployment arrangements in time to avoid missing opportunities.

Of course, because telegraph operators need to master Morse code, they need to learn the English alphabet, need to learn hua Xia pinyin, which requires very smart and careful young people, but this, Xia Xue is not very worried, the Tang Dynasty is a big country, the population is large, it is not very difficult to select thousands of smart and careful people, Xia Xue asked for the selection of telegraph personnel regardless of gender, women can also participate in the selection, she knows that many telegraph receivers in later generations are women, because many women are not only smart, but more careful than men.

At present, through the rule of Zhenguan by Li Shimin, Taizong of the Tang Dynasty and the scientific and technological help of Xia Xue, the productivity of the Tang Dynasty has been greatly improved, the problem of food and clothing for the people of the Tang Dynasty has been initially solved, the country and the people are safe, and the people live and work in peace and contentment. The population of the Tang Dynasty has grown from less than 10 million at the end of the Sui Dynasty to more than 20 million people, Xia Xue estimates that according to the current population growth rate, the population of the Tang Dynasty should exceed 40 million in ten years, which is already the most populous country in the ancient East.

After listening to Xia Xue's introduction to her telegraph, Li Shimin was overjoyed, hugged Xia Xue and kissed a few times, "There is Xue'er, I have no worries about Datang!" ”

Li Shimin immediately made arrangements and selected special personnel to set up radio signal relay stations at a number of suitable locations throughout the country according to the requirements of Xia Xue's conditions. In addition, we will select outstanding talents to work in the operation of wireless telegraphs throughout the country, regardless of gender, and women can also participate in the selection. After passing the examination, they will be stationed in various local governments and military offices across the country, and their treatment and benefits are very high.