The ups and downs of life in the Siheyuan

At present, Nuwa 1 is mainly involved in the design of the manta ray body, mainly considering its appearance and motion simulation.

But if you want to develop an excellent underwater drone, you need to break through underwater communications, intelligent clusters and underwater intelligent bionics.

Underwater communication technology is one of the key factors to achieve intelligence. Underwater control, data communication, image transmission and collaborative operations are all inseparable from the basic guarantee of underwater communication.

Factors such as transmission rate, transmission interference, and transmission distance are all core technical difficulties in underwater communications. They are also the prerequisite for leap-forward development in realizing intelligent, clustered, and coordinated combat modes.

When Li Yuan designs drones, he no longer considers individuals, but first thinks of coordinated operations in groups.

This puts forward requirements for individual intelligence.

In this regard, the laboratory has been accumulating experience and has continued to accumulate experience in the actual use of Red Arrow 1, Queen Bee and shuttle aircraft.

The only difficulty now is underwater communication.

As we all know, electromagnetic wave signals will attenuate rapidly in seawater, and the transmission distance underwater is very limited.

For example, in early submarines, when communicating with the base, they needed to risk surfacing, complete the communication, and then dive quickly.

Li Yuan learned through checking the information.

In the 20s, underwater acoustic communication systems appeared, using analog modulation technology to achieve communication between submarines and surface vessels.

In the 20s, with the rapid development of signal processing technology, digital modulation technology began to be applied to underwater acoustic communication systems.

Underwater communication is very difficult, mainly due to the multipath effect, time-varying effect of the channel, narrow available bandwidth, and severe signal attenuation, especially in long-distance transmission.

Underwater communication is very slow compared to wired communication because underwater communication uses sound waves rather than radio waves.

The principle is to convert text, voice, image and other information into electrical signals through an electrical transmitter. After the information is modulated and processed by an encoder, the transducer converts the electrical signals into acoustic signals.

The acoustic signal passes through the medium of water and transmits the information to the receiving transducer. At this time, the acoustic signal is converted into an electrical signal.

Li Yuan has already mastered this skill of signal modulation and transformation.

In the past electronic technology basic skills book, there was relevant knowledge about Phase-Shift Keying (PSK) and Quadrature Amplitude Modulation (QAM).

Knowing the principle, he can directly carry out digital adjustment communication technology.

Nuwa 1 is designing the appearance and internal maneuvering structure of the underwater drone manta ray, as well as selecting appropriate materials.

Underwater communication technology can only be developed by Li Yuan himself.

Thinking of this, Li Yuan called Representative Tong.

Ten minutes later, there was a knock on the office door.

"Tell me, if you lie to me this time, I will steal all the good things in your office."

Saying uh, he looked at the showroom to the south.

Li Yuan smiled and said, "You must have this ability."

"Oh, you look down on me, don't you?"

"Okay, didn't you say you wanted me to help you design high-speed, long-range missiles..."

Upon hearing this, Representative Tong immediately became excited, "What, do you have an idea?"

"No, I didn't say it was about missiles."

The child representative who was dodged raised his hands and said, "Okay, you can continue."

"I'm not good at missiles, but our laboratory is good at drone research."

Next, Li Yuan briefly explained the functions of manta rays.

The more the child representative listened, the brighter his eyes became.

"Good thing, if this forms a school of fish, the offshore sea will be our world." Representative Tong danced excitedly.

For an old man who is almost 50 to behave like this shows how deep the resentment is in his heart.

When I heard such good news, I couldn't help but feel excited.

"If a submarine is used as a mother warehouse and remotely commanded, it will no longer be just offshore defense. It can go deep into the ocean and reach the enemy's offshore waters."

"Oh, why didn't I think of that!

Hahaha, okay, then we will also cruise in their offshore waters and see each other’s faces.”

“It will definitely happen.

However, the core of this technology is underwater communication and underwater networking.

I need a team, considering this is military technology, so if I find you as soon as possible, you have to help us contact the experimental base."

"No problem, this kind of good thing is something the navy can only ask for."

After seeing off Representative Tong, Li Yuan called Guo Kai over.

"Xiao Guo, do you have any projects on hand recently?"

"It's still a matter of improving the drone networking algorithm. However, Hao Wei is mainly leading the team to complete this aspect, and I mainly help with testing."

Hearing the question, Guo Kai's heart stirred. He knew that he must be assigned a new project.

"Well, you should summarize the project at hand as soon as possible. Next, there is a drone project that will be handed over to you."

The joy on Guo Kai's face faded a little, and he cursed in his heart, "Why is it another drone?"

"Before, you played with something that flew in the sky, but this time we made one that swims in the water."

Then, he explained to Guo Kai the working principle and design concept of the manta ray.

The more he listened, the more excited he became. As a technical worker, the last thing he fears is challenges.

"Director Li, don't worry, leave this project to me and I will do it beautifully."

"Okay, I will be responsible for the mechanical transmission and appearance, and I will be a member of your project team from now on.

You are now focusing on underwater communications. For the software part, you can contact Liu Yang.

I have some ideas that I can tell you."

Next, Li Yuan explained to him the principles of underwater communication, as well as the FSK and QAM used.

"Director Li, although these have a certain foundation, I still have to digest and absorb them."

"No problem, you can focus on project management. I can be responsible for the design of the transceiver module for underwater acoustic communication."

"That's great, I'm still worried about this."

"Okay, you go back and prepare a project plan for on-site testing. I have entrusted Representative Tong to help contact the military."

"OK".

From that day on, in addition to his daily routine of wandering around various project teams, Li Yuan began designing transceivers during the rest of his time.

He used digital coherent modulation technology and got the first version of the transceiver in more than a month.

Communication tests were performed on the test board, which basically met the design requirements.

In the Bohai Bay, during testing, once the distance exceeded 1 kilometer, communication became intermittent.

Through the analysis of the received waveform, we found problems such as multipath effects, time-varying effects, narrow available bandwidth, and severe signal attenuation on the channel.

Li Yuan reworked the design to compensate for channel distortion, added a decision-making feedback equalizer and a second-order phase-locked loop, and spread spectrum the channel.

In order to reduce the time of the experiment, he designed all the above changes to have adjustable parameters.

The transceiver can be initialized and configured through an I2C bus.

So when the time entered late autumn, the transceiver design was successful.

Comprehensive tests were conducted in the Bohai Sea, Yellow Sea, and South China Sea, and all met the design expectations.