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

Lu Qinghe stared at the topographic map for a long time, the tip of her pencil resting on the contour line near the intersection of the north and south points.

To the east of that vast Gobi Desert, there is a rocky mountain ridge with an elevation difference of 180 meters.

"The intersection of the North Point and the South Point is fake."

Her tone was flat, as if she were stating the weather.

Chen Zhiyuan leaned over from behind her to look at the picture, and Lao Zhou also put out his cigarette and came closer.

"How can you be sure?" Old Zhou asked.

Lu Qinghe released his hand from the topographic map, letting the pencil tip slide along the direction of the rocky ridge on the east side.

"The north and south points are 900 meters apart, and the line connecting them is almost parallel to the eastern ridge. The signal comes from the northeast and hits this ridge. The reflection angle will cause the orientation judgment of the two points to be biased in the same direction. Both points receive reflected signals, so the intersection will be a false intersection."

She turned her head to look at the azimuth line of the third point to the west.

"The point to the west is at the mouth of the dry gully, which is the farthest from the ridge. To the south, there are only low earthen mounds, which do not constitute an effective reflective surface. The signal received from it is the cleanest, and the azimuth is the most reliable."

Chen Zhiyuan stared at the three lines on the diagram, his brows furrowing.

"So, the real direction should be based on the third point?"

"We can't use just one point." Lu Qinghe shook his head. "The fifth point written by that person in Beijing is right. It only counts if three stable azimuth lines intersect. But now both the north and south points are affected by reflection interference, so we can't get the true azimuth."

She straightened up, walked to the corner of the communications room, found a larger topographic map, unfolded it, and placed it on top of the original one.

"I need to move a little."

The cigarette in Old Zhou's mouth almost fell out.

"Which one should we move?"

"North Point. Move one kilometer northwest to the edge of the salt flat. The terrain there is low and flat, with no highly reflective surfaces around, offering a completely open view to the northeast."

"Move it in the dead of winter? The coaxial cable will have to be re-laid." Old Zhou's face was very grim.

"We can do it during the day tomorrow, there's still time." Lu Qinghe tucked a pencil behind her ear. "Tonight, mark the North Point data as pending verification, don't use it for the final judgment. I'll send a telegram to Beijing first, telling them the results of the first night."

Chen Zhiyuan watched her walk to the telegraph machine and sit down, her fingers flying across the paper, her handwriting strong and neat.

He had a feeling he couldn't quite explain.

The female technician never questioned the general direction of Jiang Ming's plan from beginning to end; she only made a precise correction at the execution level.

Neither blindly follow nor deny; like a scalpel, precisely cut away the parts that are unsuitable for the situation and keep what is usable.

After the telegram was finished, Lu Qinghe handed it to Chen Zhiyuan for review.

Finally, she asked Engineer Jiang to confirm: if the reflecting surface is a rocky mountain ridge, how should the relationship between the signal reflection deflection angle and the incident angle be estimated?

After reading it, Chen Zhiyuan added his own words at the end.

"Jiang Ming is more professional than you think. Don't put on airs when you call back."

The telegram was sent that night.

Beijing, the Third Electronics Factory.

When Jiang Ming saw the telegram in the confidential room early the next morning, fine snowflakes were falling outside the window, making a soft rustling sound as they hit the glass.

He looked at the data first, then the questions, and finally saw Chen Zhiyuan's personal note. His lips immediately curled down.

Putting on airs?

When has he ever put on airs?

But Lu Qinghe's question did touch on a point he hadn't quite grasped.

The relationship between the reflection deflection angle and the incident angle of a rocky ridge, requiring an feasible estimation method without any instruments to measure the incident angle, cannot be solved simply by referring to textbooks.

All five of his psychic readings that day revolved around this issue.

The pioneer of the "Firestorm" theory offered a crude but practical approximation: shortwave radiation hitting a rough, stone surface primarily results in diffuse reflection. The intensity of reflected signals deviating more than twenty degrees from the mirror surface drops to less than one-tenth of the intensity of the direct reflection. Therefore, any location with intensity less than one-third of the direct reflection can be marked as a suspicious reflection.

The female pioneer of precision instruments added the following criteria: the reflected signal will drift in azimuth as the position of the emission source changes. The deviation in the direct direction does not exceed ±2 degrees, while the deviation in the reflected direction can reach ±8 degrees or more.

The final key insight comes from historical fragments: if an enemy radio station changes its frequency or adjusts its power, the azimuth of its direct beam remains the same, but its intensity will change; the azimuth and intensity of its reflected beam will change simultaneously.

The best way to verify this is through the other party's own adjustments.

In the afternoon, I called back and compiled a list of three executable criteria.

First, azimuth data with an intensity less than one-third of the strongest point are marked as suspected reflections and are not included in cross-calculation.

Second, if the deviation in the same orientation does not exceed plus or minus two degrees for three consecutive days or more, it is considered a reliable line; if the deviation exceeds five degrees, it is discarded.

Third, when the other party changes frequency or power, the orientation changes with the direction of reflection, while the direction of direct radiation remains unchanged.

At the end, he added: "Comrade Lu's relocation plan is correct. Using the edge of the saline-alkali flat as the new northern point can avoid the eastern ridge to the greatest extent. The third criterion can only be verified when the other party changes the frequency again. Until then, use the first two criteria to filter the data."

The telegram was sent.

Northwest China, two days later, at night.

The north point has been moved to the edge of the saline-alkali flats, and the newly laid coaxial cable is buried half a foot deep in the frozen soil.

Lu Qinghe personally calibrated the antenna level at the new location and used a compass and the light on the top of a distant iron tower to perform double azimuth alignment.

At 10:19 p.m., the abnormal pulse reappeared.

Record data at three points simultaneously.

After ten minutes of recording, the three sets of data were run back to the base communications room by the communications soldier.

Chen Zhiyuan marked the three sets of numbers on the topographic map.

New North Point 338 degrees, moderate to strong.

South point 324 degrees, weak.

The third point, 340 degrees to the west, is strong.

The pencil in his hand stopped.

The azimuth lines of the new north point and the third point are almost parallel, differing by only two degrees.

The south point is more than ten degrees off and has the weakest signal. According to Jiang Ming's first criterion, it can be discarded directly.

Only two lines remain.

Parallel, not intersecting, cannot be positioned.

Just as Chen Zhiyuan was about to frown, Lu Qinghe walked in from outside the door, slammed the notebook on the table, and opened it.

"You only looked at the azimuth, not the time deviation I recorded."

She pointed to a column of numbers in the notebook.

"For the same pulse, the third point in the west received it about 0.4 seconds earlier than the new northern point. The average time is stable between 0.3 and 0.5 seconds."

Chen Zhiyuan stared at the column of numbers.

"Did the signal arrive from the west first?"

"It didn't arrive from the west first." Lu Qinghe picked up a pencil and drew an arc on the topographic map. "The signal source is closer to the third point. The two azimuth lines are parallel, indicating that the source is very far away and the directional difference is not obvious. But the time difference indicates that it is not infinitely far away in the due northeast, but rather deviating to the west within a finite distance."

She drew an extension line along a 339-degree direction, roughly calculated the distance range using the time difference, and finally the pencil tip landed on an area marked with a dotted line.

The area was marked as: Abandoned Camel Trail.

Old Zhou leaned over for a look, and his expression changed.

"Before liberation, that place was an old route used by mule caravans and camel caravans. After the highway was built, it was abandoned, and now even herders don't go there anymore. There are several collapsed old post stations and dry wells inside. The terrain is low, so they can't be seen from the outside."

Lu Qinghe put down her pencil and straightened up.

The communications room was silent for a few seconds.

Chen Zhiyuan closed the notebook and sat down next to the telegraph machine.

"Heading to Beijing. The three corrected azimuth lines are pointing to the same abandoned camel trail for the first time."

He paused here, then added a few more words.

"Request instructions on the next steps."