One afternoon in late summer, the sun was scorching and cloudless, and Chang'an City was still bustling. Outside the Patent Office, casual guards were on guard. The patent display laboratory in the Patent Office was almost crowded with people.

The laboratory is divided into "30" by screens, which means that the middle position is divided into eight compartments by screens. Each compartment is equipped with high-legged tables and high chairs, circuit devices are placed on the table, and telegraph mailers and receivers are sitting on the chairs.

Some people were walking back and forth in the compartment, holding wires in their hands, as if they were wiring.

The wall clock hanging on the wall, and the pointer walked to twelve o'clock, Yu Wenwen, dressed in casual clothes, looked at the pocket watch in his hand, and then looked at the compartments.

He looked like he was not sleeping enough, not because he had excessive "fight" last night, but because he simply couldn't sleep: Today's experiment was too important, and when he thought that the results were true, how could he fall asleep?

Half a month ago, he learned a news: someone applied for a patent at the Yizhou Patent Branch, and the content was a new type of telecommunications technology.

The patent applicant said that he invented a new telegram communication technology, which has two performance characteristics: one is to enable the simultaneous sending and receiving reports between two points in a line.

Second, on a line, the two ends can calculate together, and there can be twelve sending and receiving points, and each point can send and receive telegrams at the same time without interfering with each other.

The above performance is not affected by the length of the telegram line. Even telegram lines that are hundreds or even thousands of miles long are not a problem (provided that sufficient current is ensured), and the lines are simple, just use the existing telegram lines directly.

Such an invention is simply incredible for Yu Wenwen, but the Yizhou Patent Branch has confirmed the effectiveness of this patent technology.

So, Yuwen Wen's first reaction was to immediately send someone to Yizhou and arrest the "abnormal human".

That’s right, only “abnormal humans” can achieve such technological breakthroughs.

But Yuwen Wen quickly changed his mind and wanted to see with his own eyes what this technology is going on. Now, the time to witness the "miracle" is coming.

Yuwen Wen drank a cup of tea and sat back on his seat. At this time, his position was in a corner of the laboratory hall, a "box" surrounded by screens. After a moment, he picked up the information in his hand and looked again.

This is a technical introduction written by the technology applicant himself, which provides a detailed explanation of the new telegraph technology he invented, and is also equipped with a circuit diagram.

Technical applicants are currently studying in Yizhou Prefecture, which is the famous "Shishi Jingshe". They have been studying "electronics" and also studying telegraphs. Therefore, the technical introductions written and their words are very "standard".

Yuwen Wen calmed down and looked serious.

The existing telegram communication relies on the switch (electric key) of the sending terminal and the electromagnet at the receiving terminal, and uses DC power as a carrier to transmit information, which is DC power.

Such communication principle determines that in a telegram line, only one party can send and one party receive, and it is impossible to send and receive telegrams at the same time.

Why?

Due to the characteristics of DC power.

Currents are divided into DC and AC, which are the basic knowledge of today's electricity. DC refers to current whose magnitude and direction do not change with time, while AC refers to current whose magnitude and direction change periodically with time.

This means that the DC electrical signals (currents) are exactly the same from an electrical perspective, while the AC electrical signals can be different due to their frequency (the number of periodic changes that AC power completes in one second).

Therefore, if you want to realize the communication of one-line multi-channel (telecommunication route, that is, communication channel) of the telegram line, and enable multiple points on a line to transmit and receive each other at the same time, you must rely on AC power with a frequency of not commuting to transmit the telegram signal.

What is its communication principle?

It is the characteristic of alternating current: alternating currents of different frequencies (the gap between frequencies must be large enough), are independent of each other in the alternating current circuit and do not interfere with each other.

Just like a single-plank bridge, although it can only allow one person to pass through, when people (alternative and alternating current) are transparent to each other, then these people (alternative current) can pass through the single-plank bridge at the same time without congestion.

This communication principle was proposed by the technical applicant, so the other party's telegram communication technology does not use DC power as the carrier, but relies on AC power, but is AC power telegram.

During this period, Yuwen Wen and his technicians studied this new technology and felt it was a bit incredible.

First of all, using alternating current to transmit telegram signals will encounter a big problem: electromagnets.

The "working state" of the electromagnet driven by DC current is completely different from the electromagnet driven by AC current.

If there is a very sensitive small magnetic needle and place the others next to the iron of the powered DC battery, then the small magnetic needle will be fixed in one direction.

Next to the energized AC electromagnetic, this small magnetic needle will constantly change direction and rotate continuously.

The reason is that the direction of DC power is constant, so the direction of the magnetic field of DC electromagnet is constant, while the AC electromagnet is exactly the opposite.

Therefore, the AC electromagnetic cannot keep the armature in a simple "open" and "closed" state, but is in a crazy state of shaking the head, and it is impossible to effectively record on the paper tape.

Yuwen Wen's technicians have been studying AC telegraph technology for many years, but they cannot make breakthroughs, so they gave up.

However, the applicant for the new telegraph technology said that he had overcome this technical obstacle.

There are two ways. The first one is Yuwen Wen has known for a long time: to turn alternating current into direct current.

The new telegraph technology requires the mutual conversion of DC and AC: the transmitter sends a DC signal, and then converts it into AC power to transmit in the line. When it reaches the receiving end, it becomes DC power, drives the electromagnet, leaving a "point" and "scratch" on the paper tape.

To achieve such a concept, special circuits or devices must be used: turning DC power into AC power requires an "inverter", turning AC power into DC power, and "rectifier" is needed. These two electrical components have long been "born".

Several transmitters on a telegram line can rely on the "inverter" to convert the DC signals emitted by each into AC signals of different frequencies, and "walking" them together.

But the question then comes: How can the receiver "filter" away unwanted "drought" from the "buzzing" current in the circuit and leave the specific frequency alternating current you want?

This requires a "current filter" that can "identify" AC current for a specific frequency to check, allowing AC current for a specific frequency to "pass the door shut", enter the rectifier, turn into DC, drive the electromagnet, and then leave "points" and "scratches" on the paper tape.

Therefore, the second method is to rely on a "current filter" to obtain alternating current signals at a specific frequency.

This kind of "current filter" has been studied by Yuwen Wen's technicians for more than ten years, but they cannot develop it even if they are alive.

Now, applicants of the new telegraph technology say that they have invented the key "current filter" to realize alternating telegraph communication.

In other words, the most important point of the other party’s new invention lies in this “current filter”.

The applicant put this technology in the color of Taoism, and was called "Tai Chi Xuan Gong".

In its opinion, DC power has positive and negative electrodes, which is the "two meter". AC power has no positive and negative electrodes, or the positive and negative electrodes are exchanged with each other, just like a yin and yang fish, so it is "Tai Chi".

"Tai Chi gives birth to two yin and two yin gives birth to four yin" is the content in the "Book of Changes". The applicant's "Tai Chi Xuan Gong" has the supernatural power of switching "Tai Chi" (alternative current) and "Tiyi" (DC) to each other, and transmitting the telegram signal to all directions (four images), without any obstacles.

With his own strength, this person has broken through the technical difficulties that many people have not been able to break through for more than 20 years.

This is an amazing "native" scientist, worthy of admiration.

Yuwen Wen thought so, closed the information, and stared at the signature on the cover, staring at it.

Patent applicant: Yuan Tiangang.

He looked to the center of the hall, looking at the busy figure, not knowing what to say.
Chapter completed!