Notes from the foothills.

Two people a mile apart with a hill between them, each with a good radio, can fail to hear each other — while a handheld with a clear view of a ridgeline can reach a repeater 15 miles off. The difference is almost never the power setting. It is what sits between the two antennas, and how high they are.

Radio that travels like light

The bands a household radio uses — the VHF and UHF channels of GMRS and ham handhelds, and the roughly 900 MHz band a LoRa mesh relay runs on — all travel in nearly straight lines, the way light does. “LoRa mesh” here means the network of low-power radios that pass short text messages hop to hop with no cell tower in the path. Straight-line travel is the fact everything else follows from: unlike the shortwave bands that bounce off the upper atmosphere to cross oceans, these frequencies go where they can be “seen,” and stop at the horizon or the first ridge.

That horizon grows with height, not power. A rough rule from the same line-of-sight math: the distance in miles to the radio horizon is about the square root of twice the antenna’s height in feet. A handheld held at head height — 6 feet — sees about 3.5 miles. Lift one antenna to 500 feet above the terrain, on a ridge, and its horizon alone reaches about 30. That is the whole reason two-way networks put repeaters on ridgelines: a single antenna high enough to see over the terrain can be heard across a wide area, where two radios down among the hills cannot see past the ridge between them.

What the terrain takes

Height buys line of sight; terrain and trees take it back. A hill or ridge in the path blocks or severely degrades the signal outright. Conifer canopy is subtler but real: pine needles are 50 to 60 percent water during the growing season, and water absorbs radio energy. A modeled 915 MHz path loses about 18 decibels over 300 feet of pine forest, and wet foliage adds another 3 to 8 decibels — enough that a marginal link in a dry February can quit in a humid July with no hardware fault at all.

There is also the Fresnel zone — the football-shaped volume of clear air a signal needs around the straight-line path, not just the sightline itself. At 915 MHz over a 1.7-mile hop that zone runs about 50 feet out from the direct path, and an obstruction poking into it degrades the link even when the line looks open. Getting an antenna ten feet above a treetop can recover more signal than a legal amplifier ever could.

What to do with it

The practical read: on these bands, height and clearance from obstructions determine range more reliably than power output. Before reaching for a more powerful radio, put the antenna higher and in the clear — a mast, a rooftop, a few feet above the canopy — and test from where you actually stand, not from the driveway. This is also the honest limit of line-of-sight radio in the foothills: it goes where it can see, and no wattage argues with a ridge. A radio that can see the ridgeline will reach it; one boxed in by trees and rock will not.

On a single radio channel, only one station can be heard at a time. If two transmit at once, they step on each other and both messages are lost — so a well-behaved radio listens first and waits for a gap before it keys up. That politeness does quiet, constant work in a LoRa mesh — the network of low-power radios that pass short text messages hop to hop when there is no cell tower in the path — and MeshCore’s newest firmware reworks how it happens.

MeshCore’s v1.17.0 release, out August 9, rebuilt the part of the firmware that decides when the channel is clear. The project describes the change in its release notes as one that “could be the most significant performance improvement for all meshes.”

Listening on a shared channel

The idea is older than radio itself: take turns on a shared line. In networking it goes by listen-before-talk — a station checks whether the channel is busy and holds off until it falls quiet. On a LoRa radio there are two ways to run that check. One is a hardware feature called channel activity detection, or CAD, where the radio chip itself sniffs for a signal. The other is to do the sensing in software, watching the radio’s own status flags.

MeshCore leans on the software path, and 1.17.0 fixes two long-standing faults in it: cases where the radio’s interrupt flags “get ‘stuck,’” and — “the big one” — proper detection of a packet’s preamble, the short lead-in a receiver uses to recognize that a real transmission is starting. Miss the preamble and a node can begin talking over a message already in the air.

The project’s own summary is that the reworked software scheme now “performs on par with hardware CAD, but without the 4 second lock-up glitches that CAD still suffers from” — which is why MeshCore still ships with hardware CAD switched off. That is a trade-off stated plainly: both methods detect a busy channel, and the software one avoids a stall the hardware one has not shaken.

Why this matters in terrain like ours: where a network is built from a small number of deliberately placed ridgeline repeaters — MeshCore’s design, and the reason it suits canyon country — those few relays share the airtime among themselves. With fewer nodes, each collision costs proportionally more, because there is no thick swarm of alternate paths to paper over a lost packet. Cleaner listen-before-talk is worth the most exactly where repeaters are sparse.

If you run a node

Two practical notes for anyone actually flashing a MeshCore device. First, 1.17.0 migrates a node’s stored settings to a new JSON format automatically on upgrade; the release notes say the old binary configuration is left in place, so a node can still be rolled back to older firmware if needed. Second, a patch — v1.17.1, August 14 — followed five days later with further radio fixes, and it is the one to flash rather than the .0.

Collision avoidance is invisible when it works. On a mesh of only a few solar repeaters, the difference is a message that arrives on the first try instead of the third.

Curious about the network? Get in touch via the contact page.

In the Highway 4 and Highway 49 corridors, word that a fire has jumped a ridge or a road is closing can reach you along several channels — and they don’t all work the same way. Sorting out which alerts land on your phone, and what to fall back on when none can, is worth doing this month — National Preparedness Month is the usual prompt — and it takes only an evening.

The alert nobody signs up for

The message that buzzes every phone at once — an evacuation warning, a flash-flood alert — is a Wireless Emergency Alert (WEA). WEA is not a subscription: there is nothing to sign up for. Officials send it through a federal system, and cell towers in the targeted area broadcast it to every capable phone connected to them. Because it rides a broadcast channel rather than ordinary texting, it gets through when the network is congested.

The catch is in that last phrase: connected to them. In a canyon, or a stretch of the corridor with no bars, there is no tower to carry the alert, and it never reaches the cabin up the draw. The automatic channel is only as wide as cell coverage — which, in this terrain, is not everywhere.

The alert you have to ask for

County sign-up systems answer a different limitation — not the dead spot, but WEA’s blunt aim. A broadcast covers a whole tower’s footprint; a county system reaches the specific numbers and addresses you register. Calaveras County runs Calaveras Alert, and Tuolumne County runs its own alert system — both built on the Everbridge platform, both operated by each county’s Office of Emergency Services. Register once and the county can reach the cell, landline, email, and text contacts you list with the notices tied to where you live.

These still travel over the phone and data networks, so they are not immune to an outage — a copper landline may ring after the cell bars are gone; a text will not. Enroll every address that matters, and re-confirm an old registration: alerting platforms change hands, and a years-old sign-up may sit on a system your county dropped.

A nonprofit app for fire alerts

Another option is Watch Duty, a 501(c)(3) nonprofit whose dispatchers, first responders, and reporters compile wildfire information from official sources and radio traffic into a free phone app. It pushes a notification when a fire it is tracking threatens life or property near you. Like the county’s text and email, it needs a data connection, so in a true dead spot it is no substitute for a tower in range — a way to stay oriented, not an official order; those come from the sheriff and NWS Sacramento.

When the network itself is down

Every option so far needs a working link — a tower in range or a data connection. When an outage takes those down, what keeps working is radio, on frequencies that never route through a carrier.

On the Highway 4 side, the Ebbetts’ Radio Safety Net runs GMRS repeaters and holds weekly practice nets on a published schedule. GMRS is a licensed service with no exam and a $35 FCC license that covers a whole household. Each county also has an amateur radio group publishing net times and repeater and scanner frequencies anyone with a receiver can monitor: the Calaveras Amateur Radio Society and, in Tuolumne, TCARES. RepeaterBook lists ham repeaters near any address by town or ZIP.

S.I.E.R.R.A works the same idea in a different band: a LoRa mesh running MeshCore — solar-powered relays that pass short text messages over radio instead of the cell network. The mesh map shows which repeaters are on the air; the contact page is the way in for anyone who wants to help run it.

None of these is an official warning channel — evacuation orders still come from the sheriff, and the Live Feed mirrors them. But a GMRS handheld, or a scanner tuned to a local net, is how neighbors keep hearing the corridor when the towers go quiet — and, like the county sign-up, it works only if set up beforehand.

In the Highway 4 and Highway 49 corridors, cell coverage is uneven on an ordinary afternoon. Add a public-safety power shutoff, or a busy fire day when half the county reaches for a phone at once, and the bars you were counting on can thin out or drop. The plan that helps most on that day is the one your household wrote down before it.

September is National Preparedness Month, and of all the readiness chores it prompts, the cheapest and most overlooked is a written household communication plan — an agreement, made ahead of time, for how your family reaches each other and where you regroup when the usual channels are busy or down. It costs nothing and takes an evening.

A few pieces do most of the work.

An out-of-area contact. Pick one person who lives well outside the foothills — a relative in another state is ideal — and make them everyone’s check-in point. During a local emergency, calls across town compete for the same loaded circuits, while a call or text to someone out of the area is often easier to complete. Each family member reports “I’m okay, I’m here” to that one contact, who relays it around. It turns a dozen failing local calls into one that stands a better chance.

Text, don’t call. When networks are saturated, a text message may go through when a voice call will not — short data messages slip through gaps a held-open voice channel can’t. Texting also leaves voice capacity for people who need a live line. If you must call, keep it brief, and space out your attempts rather than redialing in a rush, which only adds to the congestion.

Put it on paper. A plan that lives only in a dead phone is no plan. Write the contact numbers and the meeting spots on a card for each wallet, backpack, and glovebox, and keep a copy in the phone too. Ready.gov has a fill-in wallet card if you’d rather not start from a blank page.

Name where you regroup. Decide two places to meet if you can’t reach each other — one near home, one outside the immediate area — so “we couldn’t get through” doesn’t also become “we don’t know where you went.”

A channel that skips the phone network. A pair of handheld radios gives a household a way to talk that never touches a cell tower. The FRS radios sold in blister packs need no license and work out of the box for short range; a GMRS license — no exam, and once one adult holds it every family member is covered under the single callsign — adds power and range on the same band for a flat $35 over ten years. Agree on a channel now, while you can read the manual, not while the lights are off.

A household plan costs almost nothing and takes one evening. Pick the contact, print the cards, name the meeting spots, and set the channel this month. The plan is already in place before the dry weeks give way to the first shutoff.

Curious about the network? Get in touch via the contact page.

When a disaster knocks out power and phone lines across a whole town, one quiet job still has to happen: counting the damage — which roads, which structures, how bad — and getting that picture back to the people running the response. Late in July, a county emergency office in Wisconsin handed part of that job to volunteer radio operators. It is a model that already operates in the Calaveras and Tuolumne foothills, and one a licensed operator here can be part of.

On July 27, an EF-3 tornado with winds near 140 mph cut a twelve-mile path through Appleton, Menasha, and Fox Crossing, downing power poles and transmission lines. The Winnebago County Emergency Management Office asked the local Amateur Radio Emergency Service — ARES, the volunteer program licensed “ham” operators run for exactly this — to help. Across three days that week, ARES operators were paired with Community Emergency Response Team members and county staff into damage-assessment teams, each assigned a section of the wreckage. The operators were the link: passing each team’s findings back to a net control station at the coordination center.

The radios did not replace the response; they carried it. And the operators were not strangers who turned up with equipment — they were an organized group the county already knew to call.

ARES and RACES

ARES and its government-activated counterpart, RACES (the Radio Amateur Civil Emergency Service), are how licensed amateurs plug into a formal emergency response. What separates them from a neighborhood radio net is the standing relationship: written agreements with the agencies, a known chain of net control, and operators who train to move structured message traffic rather than just talk.

This is not theoretical in our counties. During the 2013 Rim Fire, Tuolumne County ARES staffed a Red Cross shelter and the county emergency operations center, running message traffic for days. Today TCARES holds agreements with CAL FIRE, the U.S. Forest Service, the Sheriff’s Office, and the county Office of Emergency Services; across the county line, the Calaveras Amateur Radio Society lists emergency communications as a core part of its program and runs a weekly net.

The honest catch is that this is work, not a purchase. A GMRS license — $35, no exam — is the low doorway for reaching family and neighbors. Being useful to a county in an incident is a rung up: it takes a Technician amateur license, which means passing a 35-question exam, then affiliating with a local group and showing up for the drills. The $35 federal fee is the small part.

None of that comes together during the emergency itself. The office in Wisconsin had a team to call because the team already existed — licensed, affiliated, and practiced — before the storm. Anyone in the foothills who wants to be on that list can start the same way: contact TCARES or the Calaveras Amateur Radio Society and ask when the next net and exam session meet.