I started with a ship full of max-level veterans, and I'm just a complete noob.

After the meeting, Jiang Ming returned to the Third Electronics Factory with the revised summary of the planning document. As soon as he entered, he asked Fang Xudong to take out the front-end circuit diagram of the new early warning receiver.

The drawings were laid out on the worktable in the confidential compartment. The previously empty device positions were now marked with input impedance, operating frequency band, and allowable junction capacitance, just waiting for the parameters of the first batch of silicon transistors to be incorporated into the design.

Jiang Ming arranged the test cards for tubes numbered seven through twelve in sequence, and circled the samples suitable for intermediate frequency amplification and short pulse shaping based on the cutoff frequency, noise coefficient, and gain dispersion.

The 24 GHz signal is first reduced to intermediate frequency by a crystal mixer, and then given to silicon tube amplification and frequency identification. The current batch of devices cannot directly process the carrier frequency, but can determine whether the short frame signal can be completely retained from the noise.

"Da Liu is in charge of welding the frequency detector, Fang Xudong checks the local oscillator branch, all leads are run along the shortest path, the grounding copper strip is pressed at a single point, and after installation, the no-load noise is measured first."

Jiang Ming pushed the component box over and added, "Don't touch tube number seven for now. Use tube number ten to build the verification circuit first, and keep tube number seven for final reference."

Da Liu put on cotton finger cots and used tweezers to pick up tube number 10, while Fang Xudong moved the capacitor bridge and signal generator to the experimental table. The two began to build the module according to the drawings.

Zhou Chengan, a college student assistant who had just been assigned to room 502, stood at the corner of the table, holding an old vacuum tube receiver parameter booklet in his hand. After looking at the new diagrams several times, he finally spoke.

"Engineer Jiang, the vacuum tube equipment currently used at Station No. 3 can still receive pulses. The fact that we've tightened the requirements for leads, grounding, and temperature drift will significantly slow down the construction schedule."

After he finished speaking, he looked at the old rack, clearly having already calculated the margin of the existing components. "If we use mature vacuum tubes to complete the reception first, and then switch to silicon tubes later, it might be more reliable."

Jiang Ming did not immediately refute him, but only asked him to connect the old rack to the standard pulse source and set the shortest set of code width in the Aksai report as the input condition.

After the vacuum tube circuit starts working, the leading edge of the pulse on the oscilloscope is stretched, two adjacent short codes stick together, and the baseline swings up and down with the power supply ripple.

Zhou Chengan adjusted the bias twice and replaced the bypass capacitor. The waveform was recognizable, but the low-amplitude signal in the protection interval was still covered by noise.

"Attenuate the input by six decibels."

Jiang Ming looked at the screen and said, "Test it again, and record the amplitude difference between the synchronization header and the first set of short codes."

After the input signal decreased, the edges of the short code quickly spread out. Zhou Chengan's pencil, which he had prepared to record, stopped on the paper, and in the end he only wrote that it could not be stably interpreted.

Jiang Ming instructed Da Liu to disconnect the old circuit and connect the newly assembled silicon transistor frequency identification module to the same signal source, keeping the input amplitude, pulse width, and power supply conditions exactly the same.

After the No. 10 tube was put into standard bias, Fang Xudong rotated the local oscillator fine-tuning capacitor, and the baseline on the oscilloscope gradually tightened. The two short codes that were originally stuck together separated, and the guard interval also revealed its complete boundary.

Zhou Chengan bent down to check the range, worried that someone might have altered the signal source when switching circuits, so he proactively checked the attenuator and pulse generator scales.

All conditions remain in place.

Jiang Ming pushed the recording sheet to him, "Measure the peak value, baseline noise, and decision threshold. Calculate the results yourself."

Zhou Chengan measured it three times in a row, substituted the numbers into the formula, and calculated that the effective signal-to-noise ratio was improved by nearly two orders of magnitude. The pencil left a heavy mark in the last column.

He looked up at the oscilloscope again. The pulses that had been dragged into a wideband by the vacuum tube hysteresis had now become narrow peaks with clear boundaries, and the baseline extended along the center scale.

"Engineer Jiang, I considered the device speed as a redundancy indicator."

Zhou Chengan closed the parameter booklet, his face burning, but he didn't try to make amends for himself. "If the pulse width is within this range, the vacuum tube can receive the signal, but it can't distinguish the contents inside."

Jiang Ming reduced the bias of tube number 10 back to a safe value. "Remember today's conditions. The difference between the equipment being able to respond and the information being usable is a whole engineering line. Once you enter 502, all judgments must be based on reproducible data."

Zhou Chengan nodded, took the temperature drift test record sheet, and wrote down the solder joint length, copper strip position, and test conditions item by item according to the device number reported by Fang Xudong.

After the initial overall adjustment was completed, Jiang Ming placed the module into a simple temperature chamber and measured the changes in pulse leading edge, frequency center and group delay under low temperature and high temperature conditions, respectively.

After the temperature rose, the frequency identification center shifted. Instead of adjusting the local oscillator, Jiang Ming added a temperature compensation resistor to the bias branch and then repeated the test using the same set of short frame pulses.

The second curve returned to the allowable range, and the change in group delay was pushed into the design boundary. Da Liu then added a fixing buckle to the compensation branch to prevent transportation vibration from changing the contact state.

When Fang Xudong sealed the records, the factory canteen had already started serving lunch. The aroma of braised pork wafted into the corridor from the stairwell, and the sounds of lunchboxes clattering and workers talking in line could be heard outside the door.

Upon smelling the aroma, Da Liu put the welding torch back on its stand. "Last night, Engineer Jiang mentioned improving the meals, and the canteen is actually doing it today. This time, we won't have to dip our steamed buns in the soup."

The people around the worktable laughed a few times, and Zhou Chengan also loosened his shoulders and back, then put the drift record into a file bag, preparing to go eat after the seal was put on.

The sound of a car came from the direction of the courtyard gate. Director Wang's jeep drove into the 502 courtyard, and two security officers carried a metal box of evidence into the archives room on the first floor.

The previously seized old railway timetables, cancelled freight numbers, and materials from five joint nodes were all packed into a box. After Director Wang completed the handover and signed the documents, he took the evidence to the higher-level task force to prepare for expanding the scope of surveillance.

Jiang Ming saw the vehicle drive out of the gate again through the second-floor window. Just as he looked away, he heard hurried footsteps in the stairwell.

Comrade Song pushed open the door and came in, clutching a high-grade waterproof film box with the Northwest Military Region's top-secret markings in his hand, the edge of the lid still bearing the transport seal wax.

"The Aksai No. 3 station has just arrived. Lu Qinghe has requested that we skip the routine summary and go straight to your judgment."

Jiang Ming wiped the machine oil off his hands, checked the film cartridge number and seal, and only took it after confirming that they matched the registration. He then placed it under the sunshade to open the seal.

The box contained two sheets of photographic paper and a copy of a military telegram. The first sheet still showed a 24 GHz pulse paper feed diagram, but the second sheet showed a long string of consecutive codes.

Jiang Ming pressed the photographic paper under the glass plate, aligned the synchronization head and guard interval with a ruler, and then split the data segments according to the previously identified short frame structure.

This batch of signals has bypassed the fixed loop commonly found in equipment self-tests. Grouping numbers, pre- and post-checks, and duplicate confirmation structures have been added to the data segments, and the three segments can also close each other.

Lu Qinghe noted at the end of the report that the same set of codes appeared successively from three directions, and the reception strength and arrival interval continued to change. The existing equipment could only retain some of the long codes, and the short codes were still lost.

Jiang Ming marked the three times the images appeared on the edge of the map, then stopped the pencil in his hand in the airspace west of Aksai and returned to the verification section on the photographic paper.

"Single-machine testing is complete."

He pushed the photographic paper in front of Fang Xudong, saying, "This set of codes has already taken on the tasks of node confirmation and data verification. The enemy's airborne radar has begun to enter the air network communication."

The atmosphere that had just relaxed in the cubicle tightened again.

Da Liu looked at the silicon tube module on the experimental table that had just completed temperature drift calibration, while Zhou Cheng'an put the old electron tube parameter book into the drawer.

Jiang Ming picked up the phone and demanded that the communications room immediately reply to Aksai: retain all original recordings and improve the time alignment level of multiple stations; the practical verification of the 502 new module should be put into the highest sequence ahead of schedule, and the first batch of retest data should be sent directly along the dedicated line.

After the order was passed down, Fang Xudong led his team to repackage the module, Da Liu worked on the docking plug and vibration damping clip, and Zhou Chengan copied the occurrence times of the three signals into the retest table.

The clock on the wall pointed to the evening of late July. A westerly wind carrying the smell of hot earth blew in through the cracks in the window, blowing the edges of the photographic paper up, only to be pressed down by Jiang Ming with blueprints of a new type of receiver.

The 24 GHz preamplifier on the blueprints, the network coding on the photographic paper, and the autonomous guidance planning document on the corner of the table were placed on the same workbench for the first time.

As the westerly wind swept over the factory, it brought thick clouds. By the time Aksai's reply reached 502 via the dedicated line, the first few drops of rain had already begun to knock on the windowpane.