Chapter 74: Baseline and Gap

The knob had a heavy drag to it. Lin Chen did not turn it immediately. He checked the stopwatch first. Eight minutes and forty seconds remained. A 0.2 dB offset—if he forced the adjustment in one go, it would cause an abrupt change in contact resistance and make the noise floor jump again. He had to compensate step by step. First, switch the attenuator to the 5 dB setting and observe the slope of the curve’s return. Second, record the knob position when the deviation fell back to 0.1 dB. Third, use the remaining time for fine adjustment.

He extended his right hand. His index finger and thumb closed around the metal knob. The pads of his fingers could feel the faint wear in the threads and the slight rebound of the spring inside. He turned it one click clockwise. Click. The green waveform on the screen dropped by 0.08 dB. He stopped. Waited three seconds. The waveform stabilized. No rebound. He quickly jotted down the reading on the graph paper: 3.2. A dull ache rose from his left foot beneath the table; the swelling in his ankle crept up along his calf like a taut rubber band cinched into the seams of his bones. He adjusted his posture, shifting his weight onto his right leg. His breathing remained even. He could not let it turn chaotic. If the rhythm broke, his hand would shake.

Second click. Click. The waveform dropped another 0.06. Total: 0.14. 0.06 remaining. He let go of the knob and picked up his pen. On the scratch paper he wrote out the calculation at speed: remaining deviation divided by step sensitivity, multiplied by the thermal drift coefficient. The result pointed to the 4.7 mark on the knob. He gripped it again, backed it off half a notch counterclockwise, then nudged it forward two millimeters clockwise. The feel in his fingertips replaced sight. He stared at the screen. The waveform slowly sank until it finally overlapped the baseline. The indicator stopped flashing and turned a steady green.

Four minutes and fifteen seconds remained.

He connected the signal source. Set the frequency to 100 MHz. Pressed output. A sharp peak appeared in the middle of the screen. He picked up the multimeter and checked the DC bias voltage at the input terminal. The reading was normal. He began recording data. Frequency points, amplitude values, signal-to-noise ratio, harmonic distortion. The tip of his pen traced an unbroken line across the page. Every number corresponded to a keystroke, a reading, a mental calculation. No pause. No hesitation. His world shrank to this workbench, this machine, and the pen in his hand. Outside the window, the diesel generator still hummed, its low-frequency vibration traveling up the desk legs into his wrist. He treated it like a metronome. His breathing followed its rhythm. Inhale. Exhale. Record. Verify.

Three minutes and twenty seconds. The data recording was complete. He ran one final full-band scan. The curve on the screen was smooth—no burrs, no abnormal spikes. He checked every parameter on the graph paper again. The error relative to the theoretical derivation was within the allowable range. He set down the pen. Folded the graph paper in half and slid it into the answer envelope. Pulled the zipper shut.

The proctor walked past him and glanced at the stopwatch. Time was up. Hand in your paper.

Lin Chen stood. The instant his left foot touched the ground, a sharp stab of pain shot through the joint. He clenched his back teeth and made no sound. Slowly, he powered down the equipment, unplugged the test leads, and returned the attenuator and multimeter to the insulated case. The zipper closing made a very soft sound. He slung the canvas bag over his shoulder. The strap bit into his collarbone. The weight was still there. He turned and walked out. He kept his stride to twenty-five centimeters. Avoided the wet patches on the corridor floor. The soles of his shoes whispered against the cement.

When he stepped out of Laboratory Three, the corridor air was cooler than it had been that morning. He leaned against the wall and slowly flexed his left ankle. The swelling pain had already turned into a steady sore numbness, and the muscles trembled faintly beyond his control. He took out his water bottle and unscrewed the cap. The water had gone completely cold. He took a sip. It slid down his throat and made his stomach cramp lightly. He had not eaten lunch. He had burned through too much energy. But he did not go to the cafeteria. Cafeteria food cost money. He walked to the corner of the stairwell and sat down. From his canvas bag he took out the last half of a cold steamed bun. He chewed slowly. His throat was dry when he swallowed. When he finished, he wiped his fingers clean with a tissue. He crumpled it into a ball and stuffed it into his pocket.

At four in the afternoon, the theory scores and raw practical-test data would be posted together on the bulletin board. He did not need to ask around ahead of time. The result was already written in those numbers. He closed his eyes and replayed today’s sequence in his head. Combined preheating. Ripple calibration. Phase-slip compensation. Manually flattening the baseline step by step. Every move had landed at the edge of his contingency plan without crossing over it. The tolerance had been squeezed to the limit, but the machine had not failed, and the data had not broken. He opened his eyes. The sky was beginning to dim. Clouds gathered again, swallowing the slant of sunlight. The smell of diesel in the wind had faded, replaced by the oily scent drifting from the cafeteria in the distance.

He stood. Walked back toward the dormitory. Twenty-five-centimeter strides. No stepping in puddles.

By the time he got back to the dorm, it was completely dark. The sound-activated light in the corridor was broken, so he opened the door in darkness. He did not switch on the light. He took off his gray shirt and draped it over the back of the chair. He removed the shoe from his left foot. The sock had stuck to the edge of the wound; he peeled it away carefully. He dabbed iodine around the wound with a cotton swab. The dark red seepage had already formed a thin scab, but the edges were still pale. No pus. The healing was slower than expected, but still within control. He applied fresh gauze and fixed it in place with tape. His movements were practiced, his face blank.

He sat on the edge of the bed and opened his notebook of wrong answers. He added a page on the phase slip he had encountered during today’s practical exam. During the transition from a cold machine to a warm one, the phase noise of the reference oscillator changed with the temperature gradient. The contact resistance of the manual attenuator would undergo tiny abrupt shifts during stepping. The compensation formula needed a time-decay term. He wrote out the derivation. The pen tip stayed steady. When he was done, he closed the notebook.

The balance on the books was six yuan and eight jiao. The train ticket had already been used. Emergency funds: zero. There was no work-study assignment tomorrow. He had to get through tonight and tomorrow morning. Wait for the result.

He lay down. The canvas bag rested beside his pillow. His mother’s letter from home was tucked against Principles of Measuring Instruments. It weighed almost nothing. He closed his eyes. There was no excitement in his mind, and no anxiety either. Only those numbers, those curves, and the drag of the knob. They meshed together like gears, tight and seamless. Sleep came quickly. Dreamless.

At seven the next morning, footsteps in the corridor woke him. No alarm clock. His body clock started on time. He sat up. Put on his shoes. Slid his left foot onto the cardboard insole. The swelling pain remained. He slung the canvas bag over his shoulder and went downstairs.

A few people were already gathered in front of the bulletin board. The sheets had been printed the night before, and the ink had not fully dried yet. Lin Chen did not squeeze in. He stood on the edge until the crowd thinned a little, then stepped forward.

Theory score: 89. Rank: seventh. Raw practical-test data: error rate 1.4%. Rank: fourth. Overall evaluation: passed. Qualified for the provincial competition.

He stared at the line. He did not smile. He did not sigh in relief. He merely lowered his gaze. Beneath the list was a line of small print: The provincial competition required reporting on the fifteenth of next month at the Provincial Electronics Institute. Participants must bring a personal equipment list and an eight-hundred-yuan deposit for lodging, meals, and equipment. Failure to report on time would be treated as withdrawal.

Eight hundred yuan.

He stood before the bulletin board while the wind made the pages rustle loudly. He took out his notebook, turned to a blank page, and wrote: 800. Days until reporting: 21. Daily disposable funds: 0.4 yuan. Shortfall: 796 yuan.

He closed the notebook. Slipped the pen back into his pocket. Turned and walked back. Twenty-five-centimeter strides. No stepping in puddles.

Back in the dormitory, he opened his canvas bag and took out the letter from home. This time, he opened it. The paper unfolded, the handwriting neat, carrying the familiar scent of soapberry. His mother wrote that the autumn harvest had gone smoothly, his father’s back injury was improving, and Xiaoman was taking medicine on time and had not convulsed again at night. At the end was one line: Chen, don’t try to shoulder the money alone. The family can still scrape some together. You just keep moving forward.

He folded the letter again and slipped it back into the inner compartment. The weight had not changed. But it pressed down more solidly now.

He sat at the desk and spread out a fresh sheet of graph paper. Then he began drawing up a list. Short-term rental prices around the Provincial Electronics Institute. Bus routes. Estimated costs for food, lodging, transport, and consumables during the provincial competition check-in period. A breakdown plan for the eight hundred yuan. Work-study channels. Used-book buyback. Managing laboratory consumables on behalf of others. Every item was marked with projected income and a time point. The tip of his pen made a fine, dense scratching sound across the paper. Outside the window, the cloud cover split along one seam, and sunlight slanted in across the wet cement floor. The wind carried the smell of soil and diesel.

Twenty-one days. Seven hundred and ninety-six yuan. Four lines interwove again. Meshed. Locked tight.

He set down his pen. Picked up his water bottle. Took a sip. The water had already gone cold. He screwed the cap back on. Slung the canvas bag over his shoulder. The strap bit into his collarbone. He walked to the door and stopped. Looked back once at the notebook of wrong answers and the insulated case on the desk. Then he pulled the door open and went out.

The window at the end of the corridor stood open. Wind poured in. He drew a deep breath. The air smelled of dust. He stepped forward.