Chapter 1498 Distorted SAR

Chapter 1498 Distorted SAR

The lights at the Yanliang base remained on all night.

When chief designer Cheng Junhong entered the conference room, more than 8 core members of the Wuzhen 8B plan team had already gathered inside. The projector projected the bottom structure diagram of Wuzhen B plan on the wall, and the air intake of the ramjet engine could be seen highlighted in the diagram.

And between the two air intakes, there is a deep square groove.

The size is just right to accommodate the reconnaissance module that was just removed from the No. 71208 J-8C.

From the beginning of the project, "Wuzhen 8" was divided into two parallel plans, A and B.

Plan B led by Cheng Junhong uses ramjet engines. Its advantage is that its range is longer than Plan A which uses rocket engines, and it can be recycled multiple times after autonomous landing. However, the cost is that its flight altitude and speed are significantly inferior to the other.

Although for most air defense systems, a flight speed of more than Mach 4 and a flight altitude of more than 3.5 meters are already in the category of being unable to be shot down, it is ultimately far inferior to liquid oxygen and kerosene power.

Moreover, the strategic reconnaissance mission itself is not sensitive to cost. Not only is the advantage brought by reusability not enough, but the issue of return must also be considered, which eliminates the range advantage.

In order to make up for the disadvantage compared to their competitors, they had to take advantage of Plan B's requirement for less fuel (rocket engines need to carry their own oxidizer, while ramjet engines only need to carry fuel) and installed two small turbine generators inside the fuselage.

In this way, compared to Plan A which can only rely on battery power, it can power more additional reconnaissance equipment.

For example, a synthetic aperture radar that can perform reconnaissance missions under complex weather conditions.

This is also their greatest confidence in the competition.

Without any unnecessary greetings, an engineer has already inserted the hard drive into a dedicated reading device, and data is pouring down the screen like a waterfall.

"Let's look at the optical channel first." Cheng Junhong's voice was calm, but it was still not difficult to hear a hint of nervousness in it.

This is his first time as chief designer, and no one doesn't want a good start.

The technicians quickly retrieved the relevant files.

As the first set of images unfolded, a suppressed exclamation was heard in the conference room - on the screen, the PHL03 rocket launcher's iconic directional tube layout was clearly visible, and even the reinforcing ribs distributed on it could be vaguely seen.

"The experimental group's optical imaging not only has a 30% higher resolution, but also a 15% wider field of view, which is completely comparable to the A-type solution," said Wang Jiaqi, an optical engineer. "This shows that reducing the size of the optical module does not significantly affect the reconnaissance performance, and there is nothing wrong with our improvement ideas."

In order to make room for the synthetic aperture radar antenna, the design team of Plan B had to carve out space elsewhere.

The corners of Cheng Junhong's mouth rose slightly. This was the first time he showed an expression close to a smile tonight, and he signaled to switch to another area.

A little further east of the rocket launcher position, there is an artillery command vehicle parked.

But according to the reconnaissance results of the J-8C, this place was empty.

"This target should have been well camouflaged in the infrared, such as an adaptive infrared camouflage net, or even some active cooling or heat reflection measures," Wang Jiaqi continued. "But the Wuzhen-8 uses the latest multi-band infrared technology, and traditional concealment measures targeting a narrow wavelength range are unlikely to completely hide the signal."

Cheng Junhong nodded, acknowledging the other party's work achievements, but her eyes had already moved to another folder in the corner of the screen -

The synthetic aperture radar imaging results stored there are the real highlight of the night.

Yuan Xiaokang, who was in charge of radar equipment integration, also sat up straighter, ready to join the discussion at any time.

The SAR radar selected for Plan B was improved on the basis of a relatively mature plan, so the development cycle was relatively short and did not require a complete design team. Only a few people including Yuan Xiaokang were sent by the China Electronics Technology Group to cooperate with the work.

However, the moment the switch to SAR imaging was made, the atmosphere in the conference room suddenly became subtle.

The initial panoramic view looked quite good. The overall layout of the rocket launcher position was clear at a glance, including the command vehicle, which could not escape the detection of radar waves.

Even thanks to the larger effective observation field of view, another group of targets appeared at the edge of the image, which looked like another self-propelled artillery unit also participating in the Firepower-Shandan exercise.

But when Cheng Junhong asked to zoom in to vehicle-level details, problems began to emerge.

The outline of a certain transport truck appeared strangely distorted on the radar image, and the body that should have been straight became wavy.

What’s more serious is that the image quality of two adjacent rocket launchers is extremely different - the outline of one is barely discernible, while the other is distorted like some kind of monster.

If he hadn't known the nature of the target beforehand, he would have probably thought it was a Transformer that was switching forms...

On the other side, Cheng Junhong's voice remained steady, but her knuckles were tapping unconsciously on the table.

The technical team quickly retrieved the new files.

There is no particularly obvious target on the other side, the only landmark is a river.

"I'll compare it with the satellite image..."

Deputy Chief Engineer Fang Dongfei was about to open the lid of his laptop computer, but his action was interrupted by Yuan Xiaokang.

"No need." The latter pointed to one part, "The outline of the river channel in this place has been broken, and it has obviously been distorted... It's quite serious."

"Damn it." Cheng Junhong stared at the image in silence, his brows gradually furrowed.

For targets such as rocket launcher positions, partial distortion does not affect subsequent interpretation, but if you want to draw topography or more detailed parts, then such results obviously cannot meet the requirements.

He was very aware of the seriousness of the problem - synthetic aperture radar was originally the trump card of Plan B against its competitors. If it did not have obvious effects now, it would become a clown.

"Can you determine what the problem is?"

Cheng Junhong turned his gaze to the other side.

In fact, when he saw the results of the reconnaissance just now, Yuan Xiaokang had already guessed the reason almost exactly.

But out of rigor and to convince the designer, he still opened the radar backend's running log.

Soon, among the dense data stream, several key values ​​were highlighted in red.

"There is no problem with the azimuth resolution of the imaging, but the high-range resolution is very poor and the stability is very poor, sometimes good and sometimes bad." Yuan Xiaokang explained, "This is consistent with our first impression of the image. The overall effect is acceptable, but the details are greatly distorted."

The conference room fell into an awkward silence, with only the hum of the cooling fans echoing in the air.

“Can this problem be improved to some extent if a smaller field of view is allowed?”

A young engineer took the lead in breaking the deadlock.

Yuan Xiaokang shook his head almost without thinking:

"The height of synthetic aperture radar... that is, the range resolution has nothing to do with the field of view angle and the angular resolution."

As he spoke, he wrote a simple formula on a piece of paper in front of him:

"In fact, SAR relies on transmitting a wide bandwidth signal and then compressing the pulse to improve the distance resolution, so the solution to this problem is actually very simple, which is to enhance pulse compression, but..."

"But the problem lies in energy distribution." Cheng Junhong continued his words, his voice was not loud but it made everyone quiet down, "In order not to affect the structural stability and air resistance, the size of these two turbine generators is very small, and I am afraid there is no extra power to enhance the back-end data processing capabilities."

"In fact, it is very difficult for generators to even maintain the current energy supply level," Yuan Xiaokang added.

He called up the radar system's operating parameters, and compared it with Feng Xuezhong's flight data, pointing to the positions corresponding to several overload peaks: "Look at these time points, it is when the imaging quality is the worst... Of course, the J-8C's flight speed is slower than the intended installation target, but we must consider that the flight altitude is also lower, so the actual power consumption situation is also not optimistic."

In theory, the solution is simple - increase power generation or reduce energy consumption.

But the former means a larger turbine generator and a heavier body, while the latter will sacrifice reconnaissance performance, both of which will make Plan B lose its competitive advantage.

For a moment, the entire design team fell silent.

In the next few hours, several compromise proposals were proposed, but they were all rejected immediately.

If they are the only plan for Wuzhen 8, then the compromise may be acceptable.

However, it is not as good as the simple and crude Plan A.

It wasn't until the clock on the wall pointed to three in the morning that Cheng Junhong finally made a painful decision:

"Collect all the test data. Tomorrow... No, I will fly back to Chengdu this morning and report to General Manager Yang first."

He closed the laptop and the metal buckle made a crisp "click" sound.

When the crowd dispersed, Cheng Junhong stayed alone in the conference room and called up the set of comparison images again - the perfect performance of the optical channel and the defects of the radar channel formed a glaring contrast.

He suddenly remembered the bold words he had said when he launched the project two years ago: "We are not going to build a disposable reconnaissance tool, but an eye in the sky that can be used repeatedly."

And now, this dream is stuck on two small turbine generators.