The Military-industrial Scientific Research System of the Academic Master Chapter 1013

Chapter 1013 Five times...not enough!

Now that the technical principles and specific research and development routes have been clarified, the 54th Institute of Electrical Engineering has moved quite quickly.

This is also due to the fact that the other party has been working in the field of ground mobile communications for many years. As the two most important projects at present, the two vehicle chassis communication equipment have actually entered the testing stage long ago.

It's just that the satellite communication vehicles among them have been limited in their performance because China's own communication satellites are poor in number and performance.

After receiving Chang Haonan's project request, the 54th Institute only took about three weeks to complete the hardware transformation of four prototype vehicles, making them equipped with complete reception-decoding-storage-encoding- forwarding function, becoming a true network coding data node.

Just for the convenience of testing, the decoding and encoding modules are designed to be completely shut down physically to minimize the performance impact of additional hardware on the control group.

As for the procedures for encrypting and decrypting information…

That's no longer a problem.

Chang Haonan had conducted tests on the wired network before, and the program at that time could be slightly modified.

In contrast, although Zhejiang University's actions are not slow, they do not have any extra stratospheric airships on hand.

It will take time to build new ones or to lower the ones already floating in the sky to collect weather data.

The progress has fallen behind a bit.

However, Chang Haonan was not prepared to change his plan because of this.

The proof of principle does not matter whether it is in heaven or on earth. .

Therefore, after the acceptance of the four modified relay communication vehicles, Chang Haonan sent them to the predetermined test area in western Mongolia Province.

As for why it is Mongolia...

Because Torch Group has a huge test field here.

Since Comrade Zhuang Bingchang has not successfully developed alfalfa and soybeans that meet the requirements, and Chang Haonan himself has not yet found a polymer material that can provide sufficient shear resistance for the sand, this land has not really started to play a role yet.

But after all, the right to use it belongs to Torch Group, and there are no large towns hundreds of kilometers around, so it is easy to get approval for radio transmission testing.

The only problem is that in 2002, there was no highway network that later spread across the country, especially in the relatively remote areas of the central and western regions.

So the four vehicles were first transported by rail from the capital to Qingcheng City, the capital of Mongolia Province, and then traveled hundreds of kilometers by themselves. It took nearly a week to get there.

Of course, during the entire process, dedicated personnel from Torch Group and the 54th Institute of Electrical Engineering were responsible for escorting the vehicle, and Chang Haonan did not need to follow him personally—

The latter's work schedule does not allow him to waste so much time on the road.

As the general person in charge of the project, Chang Haonan only flew to TMTZQ Bikeqi Airport the day before the test.

Then on the morning of the next day, he transferred to a Z-12 helicopter belonging to the Air Force Search and Rescue Brigade of the Beijing Military Region and arrived at a general aviation airport near the test site.

When the helicopter landed, Wu Wei and others, who had already arrived here in advance, were naturally waiting near the apron.

The general aviation airport mainly serves various types of helicopters, as well as small gadgets such as Y-5.

The site conditions are naturally much worse than those of common civil aviation airports.

Even the runways and aprons are unpaved surfaces that have only been hardened.

Chang Haonan did not have much experience in helicopter rides before.

So, he jumped out of the cabin as soon as he confirmed that the helicopter had stopped.

Immediately afterwards, I was blinded by the dust that had not completely fallen back to the ground...

Fortunately, the people who were picking up the plane were far away, so they were walking over slowly and did not notice Chang Haonan's little embarrassment.

"Report to Mr. Chang."

Wu Wei came to Chang Haonan:

"According to the previously determined process arrangement, all inspections of the four prototype vehicles have been completed and are just waiting for you to officially issue the test order!"

Not far behind him, four SX2190 chassis communication vehicles were parked in pairs under two sheds made of camouflage cloth.

Looking at the disgraced people in front of him, Chang Haonan took a deep breath, took two steps forward with emotion, and shook hands with Wu Wei:

"Thank you for your hard work."

Following the former's gaze, Wu Wei lowered his head and looked at his earth-colored clothes:

"Hey...where did this go..."

"We wish we were out on business trips for ten months out of the year. We have never seen anything like this... we have already gotten used to it."

As he spoke, he reached out and brushed off the dust on his clothes.

But the effect is obviously not very good.

So I had to change the topic:

"Mr. Chang, the logistics comrades at the airport here have left lunch for you. Look..."

Chang Haonan didn't eat much in the morning. It was already past afternoon and he did feel a little hungry.

But after looking at the four test vehicles in the distance with even the disk antennas deployed, I still felt that there was no time to waste:

"Pack the whole lunch box for me, and find an empty space to take a sip during the test..."

The four communication relay vehicles, according to the test plan from easy to difficult, will start from being 5 kilometers apart from each other, and gradually extend the distance in steps of 5 kilometers, until the distance is 30 kilometers apart.

Subject to the influence of the height of the antenna and the curvature of the earth, the longest distance this type of communication vehicle can conduct direct communication is 30 kilometers.

No matter how far you go, you have to use scattering communication methods.

On the contrary, it is not conducive to the conduct of today's test.

As Chang Haonan officially ordered the test to begin, cars No. 2, 3, and 4 left the parking lot in sequence and drove west along a dirt road.

As the signal transmission source, the No. 1 vehicle does not need to move. At this time, several technicians have begun to erect the antenna and raise the mast.

The initial communication test with an interval of 5 kilometers did not require this thing.

But the back is essential.

A few minutes later, Chang Haonan also took Wu Wei into the compartment of Car No. 1.

In fact, a conference room was set aside at the airport tower as the test command center.

However, in order to see the results as soon as possible, Chang Haonan chose to get on the bus in person.

Although the road conditions on unpaved roads are very poor, a hundred kilometers is not a very long distance for a vehicle.

About half an hour later, car No. 4, the farthest car, also reported that it had arrived at the predetermined location 15 kilometers away. then.

The first round of testing has officially begun.

First, naturally, there is the control group.

That is to say, according to the traditional relay mode, the relay station only receives and forwards data without processing the data.

"All cars are in place!"

On the radio, the voice of the on-site test commander Fu Mingyi came:

"Car No. 1, start sending data!"

For a time, in the originally noisy carriage, only the hum of the air conditioner and communication equipment was working, and the breathing of a total of four people, including Chang Haonan.

The data content used for the test was set by Chang Haonan in advance, so the operator did not need to input anything on site.

Just select the content on the operation interface and send it.

However, after all, the program took less than a month to compile quickly, so there was no need to consider issues such as UI interaction.

Not to mention others, even Chang Haonan himself was a little nervous looking at the slightly crude interface.

Fortunately, the basic functions are relatively complete.

It didn't take long for the data transmission to come to an end.

There is no doubt that even without looking at the specific results, you can tell just by feeling that the results are not optimistic -

Network throughput is not the "average network speed" as commonly understood. The test method is not to transmit a certain amount of data files and then divide it by the final time. Instead, it sends a certain number of frames at a certain rate and calculates the transmission speed of the device under test. frame.

If the two are equal, then increase the sending rate and retest until the number of frames received is less than the number of frames sent, and the corresponding rate is the network throughput.

Therefore, it can be basically considered that the shorter the test time, the worse the results.

In addition, it is not difficult to see that although the result obtained by this test method is a bandwidth unit of one byte/second, it is not only related to the transmission bandwidth.

What's more important is stability.

"1.4 kilobytes/second..."

Almost as soon as the numbers appeared on the screen, Wu Wei read it subconsciously.

Even at the beginning of the 21st century, the results were shockingly slow.

As he had estimated before, using communication vehicles for multi-hop transmission on the ground with poor transmission conditions would not end well.

In fact, the measured throughput on the No. 2 bus is as high as more than 170 kilobytes/second.

By car number three, there are still about 30 kilobytes/second left...

Car No. 4 only has 1.4 kilobytes/second left.

It is enough to see the devastating impact of adding relay nodes on transmission speed.

Of course, such exaggerated results are indeed special cases caused by large local natural disturbances.

But the trend is always correct.

"Turn on the encoding and decoding functions of each car number and try again!"

Chang Haonan recorded the experimental data and then ordered on the radio.

For him, the worse the results in the control group, the closer they were to success.

However, the premise of everything is.

The experimental group can really measure better data.

As the cooling fan of the cabinet started whirring again, the second test officially began.

Theoretically, after the encoding and decoding functions are enabled, the network throughput will approach the Shannon limit.

Although there will still be many effects in actual operation, no matter what, the results should be better than before.

The testing process certainly lived up to expectations.

It lasted several times longer than the first time.

Although there is only a positive correlation between the outcome and the length of time, rather than directly proportional to it, this is at least a good sign.

It wasn't until more than ten minutes later that a number representing the throughput of Car No. 4 popped up on the screen as before.

"6.8 kilobytes/second!"

This result made Wu Wei's eyes light up.

You know, these numbers themselves do not represent the true level of his communications vehicle.

But the improvement is real.

Nearly 5 times!

He has no doubt that if his own products use this technology, their performance will not be completely outdated even after 5 or even 10 years...

"Mr. Chang, this..."

He looked at Chang Haonan excitedly, ready to express his congratulations.

But when he said it, he realized that the other person's face... didn't seem very good-looking.

"That's wrong..."

Chang Haonan frowned slightly, stared at the results on the screen and murmured.

The slightly weird reaction immediately confused Wu Wei:

"No...what's wrong?"

What greeted him was a moment of silence.

After a while, Chang Haonan said softly in a tone that was unclear whether he was talking to himself or answering a question:

"I tested it on a wired network before, and the result was never 15 times lower...Why is the effect this time reduced by two-thirds?"

Hearing these words, Wu Wei almost choked on his own saliva -

Good guy, does this mean that the five times improvement is not big enough?

(End of chapter)

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