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

Jiang Ming returned to the 502 confidential compartment, first locking the door, then placing the document bag under the lamp, and using a letter opener to cut open the seal. Inside were Lu Qinghe's military records, three photosensitive paper waveform diagrams, and a handwritten instruction sheet.

When the paper was pulled out of the envelope, the only sound in the room was the ticking of the wall clock. The waveform diagram was densely packed with black bars, with pulse intervals ranging from milliseconds to longer pauses marked in sequence. Lu Qinghe wrote down the date of each reception, the direction finding angle, and the recording device number in red pen. The last line asked the Chinese side to confirm whether to continue with the single-point test.

Jiang Ming first read the direction finding angle, then looked at the pulse arrival time. The scales on the three graphs were not completely consistent, and there was a slight deviation in the paper feed speed of the second paper. He took out the slide rule, recalculated the time scale of each graph, and then arranged the waveforms into a long line along the table.

Lu Qinghe provided the observation results, but the content sent by the other party could not be confirmed by Station No. 3. Jiang Ming could only make a judgment based on the recurring time relationships and could not write the guess into a conclusion in advance.

He stacked the three waveforms under the glass plate, adjusted the angle of the lamp, and the first pulses gradually overlapped. The originally scattered strips appeared continuously in the same position, with the width and interval remaining stable. However, the strips behind were divided into several groups, with short codes and long codes alternating in a fixed order.

Jiang Ming used a blue pencil to draw lines along the overlapping parts, and then used a red pencil to mark the intervals after each group. The duration of the first segment was the same, the code width within the group was divided into two types, and the same protective interval was left between groups.

He wrote down the words "synchronization segment," "information segment," and "protection segment" on a blank sheet of paper. Then he moved the third image closer to the light and checked the two sets of pulses in the second image that had been widened by the paper feed error.

After error correction, the code widths still fall within two discrete intervals. The timing structure becomes clearer as the number of observations increases, and the eleven pulses recorded by the No. 3 direction finding station are thus linked to the same rule.

Jiang Ming placed the red and blue pencils side by side, opened Lu Qinghe's instruction page, and circled the sentence at the end of the letter: "If this is encoding, the other party may have already moved from equipment testing to network communication."

"It's not a meteorological echo," Jiang Ming muttered to himself, his gaze still fixed on the waveform diagram.

He converted the repetition time of each header segment into the synchronization code length, marked the width of the two types of information codes as zero and one respectively, and left the missing check bits in the space at the end of the frame. The reconstructed format was not complete, but the outline of the data link was clear enough.

If such pulses are only used for ranging, the transmitter needs to wait for the echo and then calculate the distance based on the round-trip time. The continuous fixed header segments and group information become useless. The current record is more like a short frame communication sent by the ground node and received by other devices.

Jiang Ming laid out the Jiuquan radiosonde data, the Soviet guidance parameter catalog, and the Aksai waveform diagram together. The three documents represent meteorological input, guidance calculation, and electromagnetic communication, respectively. On the surface, they are separate from each other, but their timelines overlap near the summer test window.

He walked to the blackboard, wrote the pulse frame format on the left, and drew the intersection trajectory of the low Mach segment in the Soviet correction package on the right. Then, pointing from the coded frame to the guidance trajectory, he marked the three steps that were yet to be confirmed: uploading, correction, and transmission.

"It can send commands and transmit tracks back." Jiang Ming added a question mark with chalk. "At this stage, we can only confirm that it has data link characteristics. Its specific uses will require more intercepted records to verify."

The door was pushed open, and Wu Hanzhang walked in with a cigarette between his fingers. He stopped at the threshold after seeing the blackboard, and the cigarette fell from his fingers to the ground, rolling a short distance before stopping at the foot of the table.

"What is this?"

"The pulse timing data sent by Lu Qinghe." Jiang Ming handed over three diagrams. "Header synchronization, information code wide grouping, fixed protection interval, all eleven groups of records match."

Wu Hanzhang took the waveform diagram, first looking at the curve, then at the frame format written by Jiang Ming. He had worked in the factory for many years on microwave and vacuum tube equipment and knew that once the enemy connected direction finding, guidance and node communication to the same link, the front line would no longer be facing occasional test equipment.

"If the twenty-four Gihertz pre-class can't keep up, then we'll be left with nothing but the wind in the Northwest."

"You also need to be able to distinguish code width," Jiang Ming said. "A single-tube frequency exceeding 300 MHz is just the first hurdle. Group delay and junction capacitance dispersion will directly determine whether the receiver can extract short codes from the noise."

Wu Hanzhang raised his hand and placed the cigarette pack on the table, his gaze falling on the two code-width sections on the left side of the blackboard, his voice lowering even further.

"Can you calculate the indicators?"

Jiang Ming took out a slide rule, wrote down the relationship between symbol width and receiving bandwidth on the table, then converted the channel phase change into group delay, and then added the passband range and allowable fluctuations of the receiving preamplifier on the blackboard.

"First estimate the bandwidth based on the shortest code width, then put the repetition period of the synchronization segment into the decision window. The group delay of the receiving branch should be kept within a small proportion of the symbol duration. The passband flatness should be controlled to the thousandth level, the junction capacitance dispersion should be within the picofarad range, and if the diffusion junction depth drifts, the phase of the preceding stage will also drift."

Wu Hanzhang looked up at the line of numbers, then reached into his inner pocket and took out the safe key.

"The funding approval has just arrived, so we'll put the conventional equipment on hold for now."

He walked to the metal cabinet, opened the bottom folder, and listed the photolithography mask machine, high-purity tungsten rhenium probe, junction capacitance measurement bridge, and microwave test accessories on the purchase order. He crossed out the original quota for supplementing ordinary oscilloscopes and general power supplies, and the silicon devices and 24 GHz preamplifier filled the entire list.

Jiang Ming took the purchase order, and after seeing the amount allocated, he placed the diffusion furnace modification drawings on top of it.

"We'll modify this furnace at the Institute of Physics first. The device process and receiver specifications must use the same set of numbers, with junction depth, junction capacitance, cutoff frequency, and group delay corresponding to each one."

"Fang Xudong is in charge of numbering, Da Liu is in charge of circuits, and Lao Sun is in charge of the furnace." Wu Hanzhang closed the safe. "I'll be in charge of materials and time."

After this arrangement was implemented, the resources that were originally scattered among silicon materials, diffusion processes and microwave devices in the factory began to move along the same list. Purchase orders, waveform diagrams and diffusion furnace drawings were bound together, and the red and blue lines on the paper stretched from the laboratory all the way to the confidential room.

Jiang Ming took out the schedule. He circled the Fifth Academy's guidance verification node in late July with a red pencil, wrote the recording date of Aksai 11 pulse groups next to it, and arranged the calculation results of the Soviet correction package for tomorrow afternoon. The three lines squeezed to an intersection in the same week.

"The Soviet side's calculations will be ready by tomorrow afternoon at the earliest." Jiang Ming pressed the tip of his pencil against the intersection. "Once they shut up, we'll take over the progress."

Wu Hanzhang stared at the horizontal and vertical red lines and did not ask any further questions about the ultimate purpose of the enemy's communication links. All he could confirm was that resources had to be in place first and components had to be manufactured first. Any waiting would reduce the means of judgment for the front line.

The phone rang suddenly. Jiang Ming grabbed the receiver, and Da Liu's voice came from the Institute of Physics, with the sound of a metal cover being dismantled in the background.

"Jiang, the diffuser tube has already started preheating. There's a problem with the thermocouple compensation wire; it looks like it's been tampered with, the connector has been switched, and the bridge reading doesn't match the standard gauge."

Jiang Ming looked at the three waveform diagrams on the table, then shifted his gaze to the newly nailed diffusion furnace modification drawings. The thermocouple compensation line number in the lower right corner had been crossed out with a pencil, and the line end mark was in the opposite direction to that on the drawing.

"Stop the preheating, seal the control cabinet, everyone stay on site, and no one is allowed to disconnect any wires." Da Liu responded, and the metallic sound on the other end of the phone immediately stopped. Wu Hanzhang had already grabbed his coat, and Jiang Ming put the pulse diagram, purchase order, and diffusion furnace drawings into a file bag, sealed it tightly, and walked towards the door.

Just as he reached for the door, the phone on the table rang again. Da Liu's voice came through the static, tinged with anxiety: "Engineer Jiang, there's a piece of newly soldered solder next to the compensation line, and under the solder joint is half an old process card. The number has been scratched off, but the furnace temperature scale on it completely overlaps with the first preheating curve we're going to run tonight."

Jiang Ming's hand stopped on the doorknob, and Wu Hanzhang also stopped in his tracks.

The pulse frame format that hadn't been erased from the blackboard was a few steps away from the furnace temperature curve on the desktop. The pages that were just two separate threads were now pulled together by the same phone call.

Jiang Ming pressed the receiver back into place, turned to Wu Hanzhang and said, "Go to the Institute of Physics and lock down the scene first."

When the two came downstairs, the factory's jeep was already running outside the door.

Before the first heat from the diffusion furnace had even entered the constant temperature zone, another unseen hand had already reached into the control circuit. This time, Jiang Ming had to nail down every trace left on-site before it pushed the malfunction into the furnace temperature.