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

Before the second tremor had even subsided, the sand wall had already pressed down on the front of the command post.

As Jiang Ming rushed out, the force of the wind that hit him made him take half a step back. The sand grains hit his bare skin, bringing a burning, frictional sensation.

The communication pole on the east side of the base was uprooted by the air pressure of the sandstorm's leading edge and crashed to the ground, leaving a series of dull metallic thuds.

The air raid whistle was still sounding, but it had been mostly drowned out by the wind.

Visibility dropped rapidly: fifty meters, thirty meters, ten meters, five.

Lu Qinghe's voice came from his right ear.

"Direction-finding vehicle! Follow me!"

She grabbed Jiang Ming's sleeve and pulled him forward, her footsteps quick and steady on the gravel ground, as if she had run through this Gobi Desert countless times.

The direction finding vehicle was parked about forty meters west of the command post. It was a box truck modified from a Soviet-made GAZ chassis, with a Yagi antenna and feeder connector mounted on the roof. The metal door on the side of the truck was being blown back and forth by the wind.

Old Sun was already crouching under the car, holding the end of a bundle of safety ropes with both hands; the other end of the ropes was tied to the axle.

Lu Qinghe pulled open the side door of the car and crawled inside, followed by Jiang Ming who rolled in as well.

The space inside the carriage was not large, with instrument racks on both sides, a narrow aisle in the middle, and an operating table and oscilloscope at the end.

The receiver's meter pointer had reached the mechanical stop to the right of full scale, and the speaker was filled with a continuous white noise shriek.

"The enemy radio station increased its power during the sandstorm." Lu Qinghe sat down at the control panel, her fingers resting on the knob but not moving it. "They know we can't determine direction in this kind of weather, so they took the opportunity to maximize the power."

Jiang Ming bent down and glanced at the waveform on the oscilloscope.

The time-base scan from left to right shows the entire screen filled with a dense bright band, with no clean frequency band from 4.8 MHz to 5.6 MHz. The peak value of the bright band far exceeds the calibration value of the first grid line.

The front end is completely overloaded.

"Which location is your DBM connected to now?"

"After the first stage of the RF front-end, the local oscillator is taken from the crystal oscillator module." Lu Qinghe pointed to an aluminum box wrapped with white tape on the lower layer of the rack. "But now the interference power is too strong, and the RF signal is saturated in the first stage amplifier tube before it even enters the DBM."

"Bypass the first stage and let the radio frequency signal go directly into the DBM."

Lu Qinghe glanced at him.

"Going into the mixer without amplification? Is the signal amplitude sufficient?"

"When the interference power is three kilowatts, the received level at the antenna port will not be lower than negative twenty decibels milliwatts. There is no need to amplify it. Direct mixing can actually avoid front-end saturation." Jiang Ming had already taken out the new prototype DBM-02 he brought from the canvas bag. "Replace it with this one, bypass the first stage, and adjust the local oscillator injection power to twelve milliwatts, which is a bit higher than eight milliwatts, to suppress common mode."

"The local oscillator module only outputs 10 milliwatts, how do you expect me to adjust it to 12?"

"Change the matching resistor." Jiang Ming pulled a resistor and soldering iron from his toolbox. "Is there power in the car?"

"The generator is under the vehicle; Comrade Sun can crank it by hand."

Lu Qinghe opened the car door and called out.

The howling of the wind and sand swept in, cutting her voice in half.

But Old Sun heard it.

Three seconds later, the sound of a hand-cranked generator came from under the vehicle, and one of the indicator lights on the instrument stand lit up.

Jiang Ming plugged in the soldering iron and waited for it to heat up for thirty seconds. Then he squatted down in front of the rack, disconnected the RF connection cable of the first stage amplifier tube, and used a short copper wire to directly jump the antenna port to the RF input of the DBM.

Lu Qinghe removed the cover of the local oscillator module on the other side, revealing the crystal oscillator and matching network inside.

Which resistor?

"Replace the 100-euro carbon film at the output end with a 68-euro one."

She used tweezers to hold the resistor's leads. When the soldering iron was handed to her by Jiang Ming, their fingers touched briefly without pausing, each focusing their attention back on their work.

After Lu Qinghe finished soldering the new resistor, he put the cover back on and tightened the two screws.

Jiang Ming checked each of the four ports of the DBM-02: the RF input was connected to the antenna jumper, the local oscillator input was connected to the crystal oscillator module output, the intermediate frequency output was connected to the frequency selective amplifier at the back, and the isolation port was connected to a 50-ohm dummy load.

"Close it."

Lu Qinghe pressed the power switch.

The oscilloscope's scan line flickered briefly before stabilizing again.

The dense, bright band is still there, but its shape has changed.

A noticeable dip appeared at the 5.3 MHz mark in the middle, where the brightness was at least six bars lower than on the sides.

The depression is no longer continuous noise, but a discontinuous pulse envelope that repeats approximately every 1.2 seconds.

Lu Qinghe turned the frequency knob of the frequency selective amplifier to 5.3 MHz and pulled the gain to the three o'clock position.

The white noise in the speaker faded away, revealing a sound underneath.

Tick-tock, tick-tock.

Morse code.

"Outpost calling!" Lu Qinghe put his ear close to the speaker and quickly wrote down the message on a piece of paper with his left hand.

The wind outside the carriage was so loud it sounded like it was going to tear the sheet metal apart. The sand hitting the carriage walls sounded like a torrential downpour of metallic particles, but the intermittent Morse code from the loudspeaker squeezed out word by word through the gaps in the noise.

"Outpost No. 4 calling command, outpost No. 4 calling command, please respond." Lu Qinghe read out the translated code, his voice tense.

The sound of running came from behind the directional vehicle. A communications soldier in a cotton military uniform crawled into the vehicle from the sandstorm, his face covered in yellow dust with only his eyes showing.

"Report! Command post has received a signal from outpost number four, requesting the orientation-finding vehicle to confirm the location!"

Lu Qinghe had already placed his hand on the orientation knob. The drive motor of the Yagi antenna hummed on the roof of the car, and the signal amplitude fluctuated on the meter as the antenna rotated.

"Azimuth 31.5, elevation -2," she reported the data.

The communications soldier turned and ran outside.

Jiang Ming straightened up, his back bumping against the corner of the instrument stand, causing him a sharp pain.

The space inside the carriage was too cramped; if two people stood up at the same time, their shoulders would touch.

"What is the local oscillator power reading?" he asked.

Lu Qinghe glanced down at the milliwatt meter on the module.

11:08.

It is nearly 50 percent higher than the previous 8 milliwatts, the common-mode residual has been reduced, and the intermediate frequency output signal-to-noise ratio has increased from 18 dB to at least 24 dB.

As the antenna on the roof was being turned back to its original position, it was blown off course by a crosswind, and a metallic screeching sound came from the feeder connector.

"The feeder cable is loose." Lu Qinghe looked up at the inspection hatch on the roof. "We have to go up and tighten it, otherwise the next gust of wind will tear the cable off."

She grabbed the wrench and started to climb toward the access panel.

Jiang Ming stopped her.

"I'll go up, you stay down here and keep an eye on the signal."

"You don't know where the feeder cable runs on the roof." Lu Qinghe tucked the wrench into her belt. "I've been on it twenty times."

She climbed onto the access panel by stepping on the crossbar of the instrument rack, leaving half of her body exposed to the sandstorm on the roof of the vehicle. Her sand-proof scarf was blown open, revealing half of her cheek, and sand particles left red marks on her skin.

Jiang Ming followed and climbed up. The wind was three times stronger than it felt inside the carriage. He gripped the flange bolts of the antenna base with one hand and kept his body low to avoid being blown away.

The feeder connector is located at the base of the antenna mast. The locking nut of an N-type connector is loosened by two turns, and the outer sheath of the coaxial cable has been worn through by sand and gravel, revealing the copper braid layer.

Lu Qinghe knelt beside the antenna pole, holding the bracket with his left hand and using a wrench in his right hand to tighten the nut back.

The wind blew between the two of them, making the back of her military uniform bulge into a hemisphere.

As the nuts were tightened, Old Sun's voice came from under the carriage, coming from the direction of the safety rope. The wind ripped it into fragments, and only half of it could be heard: "...Get down...it's too windy..."

Lu Qinghe put the wrench away and moved it back towards the inspection port.

Jiang Ming rolled down first, and after her feet landed on the carriage floor, she looked up and stretched out one hand.

She grabbed his hand and slid down from the access panel. When she landed, she lost her balance and leaned forward, her shoulder hitting his chest. She stopped for less than half a second before straightening up.

Neither of them spoke.

Lu Qinghe retied the sand-proof cloth, walked back to the control panel and sat down.

The signal from the loudspeaker was still there, and the Morse code from outpost number four had turned into a continuous, repetitive call.

Then the signal content changed.

It is no longer a call to the command center.

Lu Qinghe's pencil stopped on the paper.

Her fingers tightened, leaving a white mark from her fingernails digging into the pencil.

"What content?" Jiang Ming asked, observing her expression.

Lu Qinghe turned the note around for him to see.

The paper contained the newly translated plain text:

Outpost No. 4 urgently reports that a large number of people have been spotted moving about three kilometers to the northeast, estimated to be about thirty to forty people, carrying equipment and gathering towards the mine. Requesting assistance.

Before the last two characters were finished being written, a string of sounds that did not belong to Morse code suddenly came through the speaker.

Gunshots.

A dense, continuous whistling sound, mixed with sand and dust, poured in from the other end of the microphone.

Then came the sentry's shouts, the words fragmented by gunfire and wind, but two words remained crystal clear.

"Enemy agents are gathering, towards the mine!"

Lu Qinghe's hand remained pressed on the telegraph key, his knuckles taut and white.

The wind was still howling outside the vehicle, the sandstorm showed no signs of abating, and visibility was still less than five meters.

Jiang Ming stared at the 5.3 MHz indentation on the oscilloscope. The outpost signal within the indentation fluctuated violently amidst the gunfire, its amplitude rising and falling like a spark that could be extinguished at any moment.

Suddenly, the gunshot in the headphones was swallowed up by a sharp, sweeping noise.

The interference bright bands on both sides of the oscilloscope jumped outwards at the same time, and the 5.3 MHz dip also shifted slightly.

Lu Qinghe suddenly looked up, her fingers pressing tightly against the earphones.