Receivers on a Hilltop

In radio, the single biggest upgrade you can make usually isn't a fancier receiver — it's height. A modest antenna with a clear horizon will crush an expensive one stuck behind a hill. Physics doesn't care how much you spent; it cares what your antenna can see.

My house is not on the best hill. But a spot I have access to, miles away, is — better elevation, a real view of the sky. So the obvious move: put the receivers up there, and figure out how to make them feel like they're sitting right next to me.

A radio site in a box

The site is a small, low-power computer — a little business-desktop-class box — with a handful of software-defined radios hanging off it, wired to antennas with an actual horizon. It decodes a statewide 700/800 MHz trunked system and the county VHF fire dispatch far better than anything I could hear from home, and streams that audio out to the public scanner feeds. On its own, though, it'd just be a box on a hill talking to nobody.

The magic is the tunnel. A WireGuard link reaches back from that hilltop to my lab, and from my side of it the remote radios show up as if they were plugged into my own rack. I can retune them, pull their audio, watch their decodes in the same dashboards as everything else. Miles of distance collapse into what looks, from my desk, like a local device.

The day it went dark

Here's the story that actually taught me how to build these.

I went up to swap the site's networking gear and renumber it onto a new address range. Did the work, packed up, drove home — and the box was gone. Dark. Unreachable. And now it's an hour away, on a hilltop, not answering.

Two things had bitten me at once. First, the computer was stubbornly clinging to its old network address — the lease it had before the renumber — so it was trying to talk to a gateway that no longer existed. Second, the far end of my WireGuard tunnel was pinned to a stale address too, so even once it had a network, the tunnel wouldn't come up. Classic chicken-and-egg: I needed the tunnel to fix the box, and I needed to fix the box to get the tunnel.

What saved me is a decision I'd made early and can't recommend enough: the tunnel lives on the bare-metal host, not inside the virtual machine doing the radio work. The management plane and the data plane are separate. So even with the radio side wedged, the host itself still had just enough of a path home for me to claw in — force a clean network lease with a reboot, restart the tunnel service so it re-looked-up where home actually was, and watch it come back. No drive. The receivers had been fine the entire time; the whole fight was just getting the box to admit it had a new address.

Building for the 2 a.m. that isn't there

That scare is now baked into the design. The site is built to survive a power blackout with nobody standing next to it: the BIOS is set to power the machine back on when the electricity returns, the boot menu auto-advances instead of waiting for a keyboard nobody's holding, the decoder restarts itself if it ever crashes, and a stray startup dialog that used to hang the whole thing now gets dismissed automatically on every boot. Pull the plug, wait, plug it back in — and a couple minutes later it has booted, dialed home through the tunnel, locked onto the trunk, and reconnected its feeds. Hands-free. I've tested it by yanking the power on purpose, which is a deeply unnatural thing to do to a computer you care about.

Now it just runs. There are receivers on a hilltop miles away, quietly pulling in signals I could never hear from my desk, piping them home through an encrypted tunnel like it's nothing. Every time I think about it too hard it still feels a little like cheating.

That's the invisible world again — just with a better view.