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

At the other end of the compass line, on the northern edge of the barren rocky beach, a cargo truck covered with a gray tarpaulin is parked behind the weathered rock.

The headlights were already off, and the tire tracks had been swept away by the driver with a branch.

Meng Dechang sat in the narrow radio room converted from a carriage, his maroon woolen overcoat pressed at the bottom of a wooden crate, and he had changed into the cotton-padded jacket that freight drivers usually wore.

The portable radio was set to its lowest transmission power, with the horizontal antenna laid out close to the rock crevice, transmitting a 7.03 MHz shortwave signal to Mine No. 04.

He had just sent the third set of verification codes, requesting confirmation of the southeast evacuation route from the mine, but no complete response came back through his earpiece.

The mine's main communication channel was still occupied by the encircling troops and jamming equipment, and the technical supervisor could only wait for the intervals between frequency sweeps to send short messages.

Meng Dechang glanced at his pocket watch and lowered the transmission power again. He was certain that a short message of a dozen seconds wouldn't be enough for the base to complete cross-direction finding.

Fifteen kilometers away, Jiang Ming had already marked the error circle of the barren rocky beach on graph paper, and then walked towards the Yuanlei-1 antenna.

"Master Sun, first loosen the pitch lock pin, and prepare to turn."

Fang Xudong followed him out of the carriage, and the wind lifted a corner of the mine spectrum chart in his hand.

"Once Yuanlei-1 deviates from the mine, the enemy station's main channel will lose pulse pressure, and the backup local oscillator can resume full bandwidth operation."

"I didn't say to open up the mine shafts."

"There's only one antenna. If we need to continue blocking the mine shafts, we can't use it to search for Meng Dechang anymore."

Jiang Ming squatted down next to the support and drew the half-power beam range of the Yagi antenna on the sand. He then took out the azimuth records of each direction finding station at the front line from the toolbox.

"Yuanlei No. 1 doesn't search for people; it's only responsible for closing the door."

Old Sun had already inserted the socket into the base bolt when he heard this, and he stopped.

"How exactly do I change the orientation?"

"The elevation angle was reduced from 314.6 degrees to 308 degrees, and the main lobe edge still pressed against the mine antenna array."

Fang Xudong glanced at the map. This angle was only 6.6 degrees off, still more than 100 degrees away from the barren rocky beach.

"We still can't find the target in the southeast."

"It didn't need to be found in the first place."

Jiang Ming drew three points on the draft paper: the mine shaft, the barren rocky beach, and the base, and then marked the three frequency paths respectively.

The mine received evacuation orders via the main communication channel, while Meng Dechang used a 7 MHz shortwave to wait for a response. The DBM-02 at the base was able to monitor the switching transients between the two sides.

Yuanlei-1 only needs to continue to suppress the main receiving front end of the mine, preventing the technical supervisor from sending complete coordinates outward from the existing frequency band.

"By locking down the main channel in the mine, they only have two options: remain silent or switch to the seven megahertz channel that Meng Dechang is currently monitoring."

Jiang Ming added a third line along the outer edge of the triangle.

"If they want to leave, they won't be able to wait for the car if they remain silent. They need to switch to 7 MHz, and the radio station on the barren rock beach will have to increase its power to respond."

"We don't chase after low-power short code signals, forcing them to light up themselves."

As Lu Qinghe got out of the car, she happened to hear the last sentence. She took the draft paper and checked the three-way frequency and time window.

"After the mine switched frequencies, Meng Dechang could continue to reply with the lowest power after sending just one inquiry, and the error margin would still be several hundred meters."

"Make it so that it can't be heard in the mine."

Jiang Ming wrote the pulse repetition frequency of Yuanlei-1 next to the seven MHz receiving window.

"The main channel is blocked with continuous pulses. After the mine switches to seven MHz, we do not completely block it. We only send narrow pulses at the code decision point."

The leading edge of each dot is damaged by the pulse. The mine can know that someone is responding, but it cannot confirm the coordinates and checksum. It can only ask the other party to increase the power and retransmit.

If Meng Dechang continues to maintain low power, both sides will waste time repeatedly on the same incomplete telegram, and the people in the mine will not be able to meet the evacuation deadline.

"This is an electronic fence."

Jiang Ming circled the triangle with a pencil, with the three sides corresponding to the main channel suppression, 7 MHz monitoring, and multi-station cross-direction finding, respectively.

"We don't go into the fence to grab the signal. Instead, we drive both sides to the same exit, then block both sides of the exit, leaving only enough brightness for positioning."

Lu Qinghe held the draft paper, her wrist swaying in the cold wind, the corner of the paper hitting the antenna bracket.

To insert a pulse at the code decision point, it is necessary to know the mine's transmission rhythm in advance and to align the modulation sequence of Source Thunder No. 1 with the 7 MHz listening station.

Too early a signal will cause the mine to abandon the receiver, while too late a signal will cause the complete coordinates to be missed. Excessive power may also burn out the mine's backup receiver, causing the induction to lose its target.

She looked up at Jiang Ming, who was adjusting the pulse modulator trigger delay. His hands moved without hesitation, compressing the three tactical nodes into a set of parameters that could be turned onto the knob.

From suppressing broadband interference to using atmospheric waveguides to burn through the main local oscillator, and then to dismantling irrational number frequency hopping, Lu Qinghe has revised his judgment of this electronics factory technical cadre twice.

At this moment, that judgment failed again.

While ordinary technicians would repair equipment, calculate frequencies, and modify circuits, Jiang Ming was using the enemy's will to survive to design communication routes, driving the two radios into a narrow frequency band that had been reserved in advance.

"The error in the decision point must be kept within one-eighth of a code; any deviation beyond that could destroy the entire telegram."

"So you're needed to monitor the code."

Lu Qinghe pressed the draft paper to his chest and stepped back into the direction finding vehicle.

"Comrade Song, take out the DBM-02 listening terminal and connect it to the backpack listening station. Use a 120-ohm isolation resistor and don't touch the local oscillator output."

Comrade Song opened the back cover of the equipment, unplugged the jumper cable from the original monitoring socket, and then connected the shielded cable to the seven MHz receiver.

Originally responsible for mixing and anti-interference, the DBM-02 was now separated into two channels to simultaneously capture the carrier phase of both the mine tunnel and the wasteland radio station.

Fang Xudong stood beside the antenna support, still looking at the three-way suppression model on the sketch.

"What if the mine didn't use the 7 MHz frequency and instead sent people on foot to deliver the message?"

"Fifteen kilometers, cross the encirclement line, and find the truck hidden behind the weathered rocks. We can't get there before dawn."

"What if they abandon the evacuation?"

"Then stay in the mine and wait for the First and Second Battalions."

Every escape route comes with a clear cost. Technical supervisors can choose, but they cannot find an option that avoids exposure.

Fang Xudong folded the spectrum diagram and walked to the standing wave meter to take over the monitoring.

"The thermal standing wave is 1.5, and it is still within the safe range after the azimuth deflection."

Jiang Ming reduced the main pulse repetition frequency from 998 Hz to 820 Hz and then adjusted the trigger delay to allow the pulse group to be inserted into the shortwave code interval.

Old Sun tightened the last bolt, returned to the booster cabinet to check the oil pressure, and found that the generator pointer was approaching the red zone, meaning it could only maintain full load for a maximum of half an hour.

"The equipment only has so much time left. If the mine doesn't change the frequency, we'll have to go down."

"It will change."

Jiang Ming picked up the walkie-talkie and reported the three-way model and the error circle of the barren rocky beach to the command post.

After listening, Director Wang instructed the No. 3 radar base and the No. 4 outpost to simultaneously turn their direction-finding antennas to the southeast, and to send all data directly to the main station.

"The first and second battalions shall continue to block the mine exit and prevent them from rushing underground prematurely. The reconnaissance squad shall search the central high ground."

"The remaining units will calibrate their positions based on the coordinate network that Jiang Ming is about to force out, load their bullets, and warm up their vehicles."

Reports from various units came through the frequency hopping gaps: the red flags in the North and West Gullys continued to shrink towards the mine shaft, and two jeeps in the southeast direction began loading personnel.

Jiang Ming pushed the pressure regulating handwheel to the ready position.

"Yuanlei No. 1 uses low-power ignition to lock onto the main channel first, without burning out the backup unit."

In the mine's listening room, the 7 MHz receiver indicator light came on again, and Meng Dechang's verification code was intermittently transmitted from the narrowband speaker.

The technical supervisor attempted to report the number of evacuees using the main communication channel. Just as the first set of codes left the transmitter, the narrow pulse of Source Thunder-1 was pressed into the receiving array along the inversion layer.

The main channel meter on the console kept hitting the upper limit, the gain that the protection level had just restored was reduced again, and the output code was reduced to unrecognizable breakpoints.

The operator switched the coupling line twice, but the pulse still fell with each transmission window.

"They had already predicted our frequency hopping location, so the main channel couldn't be transmitted."

The technical supervisor looked at the evacuation map to the southeast. Gunfire was gradually approaching from the two trenches outside the mine, and they had less than half an hour left.

On the far right of the control panel is a separate switch, painted red, which is connected to the seven-megahertz spare frequency band that has never been used during normal duty.

He grabbed the guillotine handle and pulled it down.