Chapter 1013 5 times is not enough!

Now that the technical principles and specific R&D routes have been clarified, the 54th Institute of China Electronics Technology Group Corporation has acted 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. The two types of vehicle chassis communication equipment, which are the most important projects at present, have actually entered the testing stage a long time ago.

It’s just that the satellite communication vehicle has been limited in its performance due to the limited number and performance of China’s own communication satellites.

After receiving Chang Haonan's project requirements, the 54th Institute completed the hardware transformation of four prototype vehicles in only about three weeks, enabling them to have complete receiving-decoding-storage-encoding-forwarding functions, becoming true network coding data nodes.

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

As for the procedures for encrypting and decrypting information...

That's even less of a problem.

Chang Haonan had conducted tests on a wired network before, and he only needed to make slight modifications to the program at that time.

In comparison, although Zhejiang University was also moving at a fast pace, they did not have any extra stratospheric airships.

It will take time to either build new ones or bring down the few that are already floating in the sky collecting meteorological data.

The progress has fallen behind.

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

The principle verification doesn't matter whether it is in the sky or on the ground.

Therefore, after the acceptance of the four modified relay communication vehicles, Chang Haonan sent them to the designated testing area in the western part of Meng Province.

As for why it is Meng Province...

Because Torch Group has a huge experimental field here.

Since Comrade Zhuang Bingchang has not yet 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 piece of land has not yet really started to play a role.

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

The only problem was that in 2002, there was no nationwide highway network, especially in the relatively remote areas of the Midwest.

So the four vehicles were first transported from the capital to Qingcheng, the capital of Meng Province, by rail, and then they had to travel hundreds of kilometers over mountains and rivers on their own. It took nearly a week to get to the destination.

Of course, the whole process was supervised by people from Torch Group and the 54th Institute of Electronic Science and Technology, so Chang Haonan did not need to follow in person.

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

As the project leader, Chang Haonan flew to TMTZQ Bikeqi Airport the day before the test.

Then on the morning of the next day, we 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 arrived here in advance were naturally waiting near the helipad.

The general aviation airport mainly serves various types of helicopters, as well as small items like the Y-5.

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

Even the runway and apron are unpaved surfaces that have only been hardened.

Chang Haonan did not have much experience riding a helicopter before.

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

Then I was blinded by the dust that had not yet completely fallen back to the ground...

Fortunately, the group of people who were there to pick him up were quite far away and were hurrying over, so they didn't notice Chang Haonan's slight embarrassment.

"Report to President Chang."

Wu Wei came to Chang Haonan:

"According to the previously determined process arrangement, the four prototype vehicles have completed all inspections and are just waiting for your official test order!"

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

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

"Thank you for your hard work."

Following the former's gaze, Wu Wei looked down at his clothes which were already stained with a layer of dirt:

"Oh... we're just getting started..."

"We spend almost ten months a year on business trips. We've seen all kinds of things... We're 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 subject:

"Boss Chang, the logistics comrades at the airport have left lunch for you. Take a look..."

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

But looking at the four test vehicles in the distance, whose disc-shaped antennas had already been deployed, he still felt that there was no time to waste:

"Put the whole lunch box in my bag, so I can find an empty space to use while testing..."

"..."

The four communication relay vehicles will follow a test plan from easy to difficult, starting with a distance of 5 kilometers from each other, and gradually increase the distance in steps of 5 kilometers, until the farthest distance is 30 kilometers.

Due to the influence of antenna height and the curvature of the earth, the maximum distance for direct communication of this type of communication vehicle is 30 kilometers.

If it is farther away, we will have to use scattering communication methods.

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

As Chang Haonan officially ordered the test to begin, cars 2, 3 and 4 left the parking lot in sequence and drove west along a dirt road.

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

This thing is not necessary for the initial communication test with a distance of 5 kilometers.

But the latter is indispensable.

A few minutes later, Chang Haonan also brought Wu Wei into car number one.

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

However, in order to see the results as soon as possible, Chang Haonan chose to get in the car himself.

……

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. 15, which was the farthest away, also reported that it had arrived at the designated location kilometers away.

then.

The first round of testing officially begins.

First, of course, is the control group.

That is, according to the traditional relay mode, the relay station only receives and forwards data but does not process the data.

"All cars are in place!"

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

"Car No. 1, start sending data!"

For a moment, the only sounds in the originally noisy carriage were the humming sound of the air conditioner and communication equipment, and the breathing sounds of four people, including Chang Haonan.

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

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

However, the program was written in less than a month, so there was no need to consider issues such as UI interaction.

Not to mention others, even Chang Haonan himself felt a little overwhelmed when looking at the slightly simple interface.

Fortunately, the basic functions are quite complete.

Before long, the data transmission came to an end.

There is no doubt that even without looking at the specific results, one can tell from the feeling that the results are not optimistic.

Network throughput is not the "average network speed" generally understood, and the test method is not to transfer a certain amount of data and then divide it by the final time. Instead, it is to send a certain number of frames at a certain rate and calculate the frames transmitted by the device under test.

If the two are equal, increase the sending rate and retest until the moment when the received frames are less than the sent frames. The corresponding rate is the network throughput.

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

It is also not difficult to see that although the result obtained by this test method is a bandwidth unit of bytes per second, it is by no means only related to the transmission bandwidth.

What is more important is actually stability.

"1.4 kilobytes/second..."

Almost the moment the numbers appeared on the screen, Wu Wei read them out subconsciously.

Even at the beginning of the 21st century, the results were so slow that they were shocking.

Just as he had estimated before, using a communication vehicle for multi-hop transmission on the ground with poor transmission conditions would not end well.

In fact, the throughput measured on car No. 170 was as high as over kilobytes per second.

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

Car number four only has 1.4 kilobytes per second left.

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

Of course, such exaggerated results are indeed a special case caused by greater local natural disturbances.

But the trend is always correct.

"Turn on the encoding and decoding functions of each vehicle and retest!"

Chang Haonan recorded the experimental data and then gave orders into the radio.

For him, the worse the results of the control group, the closer it was to success.

However, the premise of everything is.

The experimental group can really measure better data.

……

As the cabinet's cooling fan started humming again, the second test officially began.

Theoretically, after enabling encoding and decoding functions, network throughput will be close to the Shannon limit.

Although there will still be many impacts in actual operations, the results should be clearly better than before anyway.

The testing process did not disappoint.

It lasted several times longer than the first time.

Although the outcome is only positively correlated rather than proportional to the length of time, it is at least a good sign.

It was not until more than ten minutes later that a number representing the throughput of car No. 4 popped up on the screen as it did just now.

"6.8 kilobytes per second!"

This result made Wu Wei's eyes light up.

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

But the improvement is real.

Almost 5 times!

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

"Mr. Chang, this..."

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

But after I said this, I realized that the other person's expression... didn't seem to be very good.

"its not right……"

Chang Haonan frowned slightly, staring at the result on the screen and muttered.

Wu Wei was completely confused by the slightly strange reaction:

"No...what's wrong?"

"..."

He was greeted by silence.

After a long 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 less than 15 times... How come the effect was directly reduced by two-thirds this time?"

Hearing this, Wu Wei almost choked on his own saliva——

Wow, so you mean that a five-fold increase isn't big enough?