Chapter 13: The Second Signal

I went back to the shack on Prentiss and didn't sleep. I pulled out my sector map and spread it on the bench and drew lines on it.

The bearing from Fletcher Street was NNW. I'd calculated it from the signal strength differential between the array on the Fletcher roof and the main receiver on Prentiss. The margin of error on that calculation was plus or minus about fifteen degrees, which was wide, but it still narrowed the field substantially. NNW from Fletcher Street, within a fifteen-degree arc, pointed to a section of the city that included the upper commercial district, the north residential blocks, and the edge of what everyone called council territory — the cluster of governmental buildings around the old courthouse where the council met.

Soren's transmitter was positioned in the warehouse building above the tunnel junction, which was roughly due west of Fletcher Street. Not NNW. My bearing had been wrong, or the signal source was not Soren's transmitter.

I'd been sloppy. I'd assumed the signal I was triangulating was the same signal Soren had described — the automated transmitter she'd deployed six weeks ago. But I hadn't confirmed that assumption against the geographic data. I'd let the discovery of Soren explain the signal, and I'd stopped questioning it.

Basic error. The kind you make when you're tired and want something to be resolved.

Now, sitting at the bench at 2 AM with the map in front of me, I corrected it. The signal on 3847 was not coming from Soren's transmitter. The bearing didn't match. Which meant there were two transmitters on the same frequency, broadcasting the same message.

Or there was one transmitter, and Soren's automated device was something else I hadn't connected properly yet.

I thought about it carefully. Soren had said her transmitter used a mechanical timer and a capacitor bank. She'd set it to transmit the message three times, on a cycle, at the same time each day. The signal I'd been receiving matched that description: three repetitions, precise interval, daily at 3:14 PM.

But I'd also noted a one-second variation in total duration between the first reception and later ones. Soren had explained this as capacitor discharge — the timing drifting as the stored charge depleted. That was technically reasonable.

Except that if the timing was drifting due to capacitor discharge, the drift should be progressive. Each day's transmission should be slightly different from the previous one. I hadn't compared them carefully enough to confirm or rule that out.

I pulled out the notebook and went through my logs. I'd recorded the transmission duration each time I'd received the signal. Three weeks of data.

The duration varied by one to two seconds, but not progressively. It oscillated. Some days longer, some days shorter, with no consistent direction. Capacitor discharge would produce a monotonic change — consistently longer or consistently shorter as the timing circuit slowed. Oscillation suggested something else. A human operator adjusting the timing. Or multiple transmitters with slightly different characteristics.

I stared at the notebook for a long time.

Two transmitters. Both broadcasting the same message, on the same frequency, at the same time of day. One from Soren's warehouse location. One from the NNW bearing — from somewhere in the council territory.

Who else knew the message?

The community in the tunnels — but they were underground and had no radio access. Elena had heard it from me, not directly. Soren had written it and set it to broadcast.

Unless Soren hadn't been the first to broadcast it. Unless someone else had gotten there before her.

I thought about the message: THE QUIET WAS ENGINEERED. THEY'RE STILL WATCHING.

Seven words. The phrasing was specific. Not the kind of thing you arrived at independently. The phrasing had to come from someone who knew — specifically knew — the history, the project, the terminology. Someone with direct knowledge.

Soren had direct knowledge. She'd built the device.

But she'd said she'd worked with others. She'd mentioned Aldren. And she'd said: I attempted to transmit through an independent channel to a contact outside Axis Corp who I believed could get it to a journalist or a regulatory authority.

The transmission had been intercepted. The contact had been removed. Soren had said she didn't know if it was pneumonia.

But what if the contact hadn't died? What if the contact had survived, and had received enough of the information before the interception to understand what they were sitting on, and had spent thirty years trying to find a way to surface it?

What if the contact was inside the council building?

I kept very still for a moment.

Then I turned on the receiver and set it to 3847 and waited.

The signal came at 3:14 PM the following day, as always. But this time I was paying different attention. I wasn't listening to the content — I knew the content. I was listening to the signal itself: the characteristics of the carrier wave, the timing of the keying, the spacing between elements.

Morse code sent by a human operator has a fingerprint. The rhythm of individual characters, the spacing between words, the particular pattern of hesitation or confidence at certain letter combinations. A trained operator has a signature as distinctive as handwriting. An automated device has its own kind of signature: perfectly regular element timing, consistent carrier power, no variation in the gaps between repeats.

I listened to the full four-minute transmission and took notes on what I heard.

Then I sat back and read my notes.

What I'd heard was not one signal. It was two signals, superimposed. The primary carrier was automated — perfectly regular, the capacitor-driven device Soren had built. Underneath it, slightly offset in frequency, was a second signal: marginally different carrier power, keying with the subtle irregularities of a human hand. The two signals were close enough in frequency and timing to sound like one clean transmission to an unanalyzed ear. But they weren't the same.

Someone was transmitting simultaneously with Soren's device. Piggybacking on the same frequency at the same time. Either they knew about Soren's transmitter and were using it as cover, or they'd independently arrived at the same frequency and time, which was too much coincidence to credit.

They knew about Soren's transmitter. Which meant they had some connection to Soren, or to the project, or to the information the signal referenced.

And they were transmitting from the council building, or somewhere close to it, in the NNW quadrant of Haven Falls.

I need to triangulate more precisely. The Fletcher Street array gave me a bearing but not a distance. To get a location rather than a direction, I needed a second bearing from a different point. Two bearings intersect at the source.

I had access to the Fletcher Street roof. I needed a second location. North of the council area, or east of it — somewhere that would give me a crossing angle of at least thirty degrees from the Fletcher bearing to produce a useful intersection.

I thought through the sector geography. The north residential district sat above the council area. I had no contacts there. The east approach was better — I knew a building on Meridian Street in the second sector that had a clear sightline north and west, a salvage depot I'd worked with twice in the last year. The owner was a man named Tolliver who ran a quiet operation and didn't ask questions when questions weren't offered.

I went to Tolliver the next morning.

He wasn't enthusiastic but he was practical. I offered him three months of priority access to any electronic components I salvaged that met his specifications — a standing arrangement worth more than most things in the sector economy — and he looked at the roof access hatch and shrugged. "You're not going to tell me what you're doing," he said.

"No."

"And it's not going to bring trouble to the building."

"Not if I can help it."

He thought about that. "You're not good at lying, Carver. You know that."

"I know," I said. "But I'm good at not being the reason trouble starts. Whatever trouble there is already exists. I'm just trying to find the shape of it."

He gave me the roof key.