“Th-thank you.”
The three of them stammered their thanks, still stunned. Before they could say more, the waitress had already set out the tableware, smiled slightly, and quickly retreated out of sight.
Bai Yang finished his dinner without further incident. After evening self-study, he rushed straight home to demand answers, wanting to know exactly what these people had told the school to make the teachers look at him as if his days were numbered. But when he got home, he found a group of people crowded in his bedroom, chatting enthusiastically. Bai Yang was startled—
“Yes, yes, that’s right, it’s Zifeng Tower, only a five-minute walk to get there.”
“Hold on a moment, we’re looking at the map.”
“Look! Old Wang, see if there are any shortcuts nearby?”
“How fast can that giant eyeball move? Let’s see if we can estimate a safe range…”
Bai Yang pushed open the door: “What are you doing?”
The three older men turned their heads simultaneously like thieves caught in the act, their expressions suggesting they’d been caught conspiring.
“Chatting with the young lady.”
His dad was holding the hand mic while Wang Ning and Zhao Bowen stood on either side of the chair, one holding a large map and the other holding a tablet computer.
“You’ve already made contact with her?” Bai Yang was somewhat surprised. He glanced at the time – it was only eleven o’clock. “This early?”
“Earlier than you think,” Zhao Bowen said. “We made contact three hours ago.”
“BG4MSR, my son’s back from school. You can continue your chat, OVER.” Old Bai readily gave up his position, placing the hand mic on the desk.
“This… isn’t it only possible to make contact after eleven? Why so early today? Three hours ago?” Bai Yang dropped his backpack and squeezed over. The Icom-725 radio’s speaker crackled with the girl’s clear voice: “BG? BG4MXH? Are you back?”
“It’s me, I just got back, OVER.” Bai Yang pressed the hand mic to reply, then turned to ask his father, “What’s going on? It’s not even time yet?”
Their experience over the past few months had taught them that this radio could only connect with BG4MSR after eleven at night, never at other times. Bai Yang had tested this himself, specifically trying at 9 AM, noon, 6 PM, and 8 PM on a weekend, but none of these attempts had succeeded.
Only connections after eleven at night were guaranteed to work.
“That’s because we’ve advanced our understanding of it another step,” Zhao Bowen pointed at the radio. “We’ve found indirect evidence that the Black Moon is a crucial factor affecting trans-temporal communications.”
“What kind of evidence?”
“The evidence is in the frequency,” Zhao Bowen answered. “It was just a hypothesis at first. During the time we took this IC-725 out for inspection, the team had several theories about the cause of trans-temporal communications. Today we successfully verified one of them—”
“I can’t stand how you beat around the bush,” Old Bai criticized. “Can’t you get to the point?”
“I need to explain the context, don’t I?” Zhao Bowen rolled his eyes. “If you’re so capable, you explain it.”
“Fine, I will!” Old Bai snorted. “The reason is very simple. We were able to contact BG4MSR early because she was already there.”
Bai Yang didn’t understand what this meant.
“That’s right, you could connect with BG4MSR at seven in the evening, always could,” Zhao Bowen interjected. “No need to wait until after eleven.”
“But I tried!” Bai Yang was surprised. “It didn’t work at all!”
“Because your frequency was wrong,” Old Bai said.
“14.255 MHz,” Bai Yang said.
“At seven or eight in the evening, she’s not on 14.255 MHz,” Old Bai said. “That’s the key.”
Bai Yang was confused.
“Then where is she?”
“Around 14.305 MHz,” Old Bai answered. “That’s what we’ve tested.”
Bai Yang didn’t believe it. He decided to grab the hand mic and ask directly: “BG4MSR, BG4MSR, question for you, do you adjust your radio frequency at night? OVER.”
“Frequency adjustment?” the girl said. “No, I’m always on 14.255 MHz.”
“See, she says she hasn’t adjusted the frequency,” Bai Yang leaned back casually against the chair.
“Of course, she hasn’t adjusted the frequency, but frequency changes don’t have to be manual,” Zhao Bowen explained. “You know about Doppler radar, right? Using changes in radar wave frequency to calculate a target’s flight speed – this principle is often used in amateur radio activities.”
“Satellite communications,” Bai Zhen said.
So-called satellite communications were a fairly common amateur radio activity. Besides direct frequency communication, repeater stations, and ionospheric reflection, HAMs could also conduct amateur radio activities using artificial satellites in orbit. These satellites responsible for relaying amateur radio signals were called amateur satellites – like the Lilac series satellites developed by the Harbin Institute of Technology, of course, the International Space Station was also a super-sized amateur satellite (the ISS played quite an important role in the world amateur radio activities). Anyone could make long-distance calls through amateur satellites, but it’s important to note that amateur satellites were low-orbit satellites. Unlike geosynchronous satellites, low-orbit satellites didn’t maintain a fixed position relative to the ground – they passed overhead at high speeds. Once there was relative velocity, the Doppler effect on electromagnetic waves became a factor that couldn’t be ignored.
When a satellite entered range, the electromagnetic waves would be compressed and frequency would increase due to the rapidly decreasing distance. When the satellite left range, the distance would increase, the electromagnetic waves would stretch out and the frequency would decrease. This principle was the same as hearing the whistle of a train change pitch as it approached and left a station.
Therefore, when HAMs communicated via satellite, they had to adjust their transmit and receive frequencies based on the satellite’s position. This was called the Doppler shift.
“I know all this.”
Bai Yang certainly understood what the Doppler effect was, but he and BG4MSR weren’t communicating via satellite, so why would they be affected by the Doppler effect?
“Don’t be impatient, let us finish,” Zhao Bowen said. “Based on current experiments, we can draw a preliminary conclusion. Around 6:30 PM, we can faintly detect a tiny signal. After 7 PM, the signal becomes clear enough for normal conversation. At that time, the frequency is 14.305 MHz, significantly higher than 14.255 MHz. Why is that?”
Bai Yang thought for a moment.
“Because something is entering range?”
“Later at night, after 2 AM, the optimal communication frequency drops to 14.235 MHz. Why is that?”
Bai Yang thought again.
“Because something is leaving range?”
“What exactly is entering and leaving range?” Zhao Bowen asked. “Think about the timing – what appears at 6:30 PM? Reaches a stable position around midnight? And then starts moving away after midnight?”
Bai Yang slapped his forehead.
“The Black Moon.”
“Exactly. This is the indirect evidence we’ve found. The radio frequency changes align with the Black Moon’s position changes. The Black Moon must be a crucial factor affecting trans-temporal communications – this is the first solid evidence we’ve found,” Zhao Bowen said. “The frequency shifts about 10 KHz per hour. That’s not a small change, which is why you couldn’t contact BG4MSR before eleven – she wasn’t within your reception range at that time.”
Bai Yang understood now.
He couldn’t contact BG4MSR during the day because the Black Moon wasn’t in the sky.
He couldn’t contact BG4MSR before eleven because the frequencies didn’t match.
In SSB mode, the transmission bandwidth was very narrow (note that any transmission occupies bandwidth – if a radio station transmitted at 15.000 MHz, it occupied a range of frequencies centered on 15.000 MHz, not just the single point of 15.000 MHz). Generally speaking, among various radio modulation methods, FM used the most bandwidth, with FM greater than AM greater than SSB greater than CW. CW was for telegraph, using the least bandwidth, but CW could only dit-dah. SSB’s advantage was that you could use it for direct voice communication while occupying a narrow frequency band. The SSB mode Bai Yang used only occupied about 20 KHz bandwidth, with his transmissions mainly concentrated in the narrow range of 14.255 MHz to 14.275 MHz. Once the other party’s signal left this range, he couldn’t receive it.
Using midnight’s 14.255 MHz as a baseline, calculating with a 10 KHz shift per hour, the frequencies in the early evening would all be higher than this number. At 7 PM, BG4MSR’s frequency was 14.305 MHz; at 8 PM, 14.295 MHz; at 9 PM, 14.285 MHz; only around 10 PM did it start entering Bai Yang’s receivable range.
This was the first time Zhao Bowen and the others had confirmed the Black Moon’s significant influence on trans-temporal communications.
“We’ve always suspected the Black Moon was the cause of trans-temporal communications, but only today did we confirm it,” Zhao Bowen continued. “We had BG4MSR cooperate with our experiment, coming online at 7 PM tonight to test frequency changes. And guess what? We were right.”
“Why does it have this effect?” Bai Yang didn’t understand. “The Black Moon isn’t a relay station, the signal isn’t being sent toward it, so why would it cause a Doppler effect?”
“Right, you’re not using directional antennas – even satellite communications need Yagi antennas. The Black Moon isn’t a relay, and this Doppler effect isn’t caused by the Black Moon’s movement speed,” Zhao Bowen nodded. “So we’ve made a further hypothesis about its influence at a deeper level. This hypothesis is quite bold… it wasn’t my idea, I’m not that daring. It came from a colleague at the Institute of Physics. He said space and time are inseparable – if the Black Moon affects time, we can’t expect space to remain unaffected. The Doppler effect on radio signals is just an external manifestation of the Black Moon’s influence on space…”
“What’s changing isn’t the electromagnetic wave frequency, but the space the waves are traveling through,” Zhao Bowen paused. “The Black Moon might be stretching and compressing space on a large scale.”