Plug a Geiger counter into your computer and join a worldwide network of volunteers. Every ten minutes real counts go to a live, open map of the background dose rate, city by city.
Everywhere on Earth a little ionizing radiation passes through you all the time: gamma rays from the rocks and soil, the building you sit in, radon in the air and cosmic rays from space. It is harmless at these levels and it differs from place to place: granite reads higher than sediment, a mountain village higher than the coast. A network of cheap detectors, each watching its own corner, shows what normal looks like everywhere, so that unusual can be seen.
A Geiger-Müller tube gives one pulse for each ionizing event. At background level that is about one every two seconds.
Counts from all detectors become the median dose rate of each city, over the last hour, 3 hours, 24 hours or 7 days.
The map is open to everyone, with a history graph per place and a notice when readings are clearly higher than usual.
From the tube to the map in four steps.
The FNIRSI GC-03 with Yarrow firmware counts raw pulses of its J321 tube and keeps a pulse counter and a clock.
A small BOINC task reads the counter and cuts it into exact 10, 30 or 60 minute bins on the clock, sent every ten minutes.
Impossible values are refused at once. A day later each stream must pass a statistical test. Only then bins count and earn credit.
Cities appear as points coloured by their median dose rate. Nothing finer than a city is ever sent or shown.
The FNIRSI GC-03 is a pocket Geiger counter with a J321 tube, a colour display, a rotary knob, a battery and a USB port. Yarrow is open firmware written from scratch for it, because the original gives nothing a computer could use.
An adaptive averaging window: quiet at background level, quick when the level rises. Dead-time correction keeps strong sources honest.
Caution, danger and evacuate levels with hysteresis, sound, vibration and light, and a plain-language guide for what to do.
From one-second detail for weeks to hourly records for years, power-fail safe, with alarm moments saved every second.
Track a daily dose budget, record sessions and compare a sample against the background with a statistical verdict.
Electric and magnetic field readings with a rising tone and bars as you approach a source or a wire in the wall.
Sixteen colour themes, 16 languages, a battery gauge with health and charge cycles, and a self test of the tube, sensors and clock.
Put the detector next to any source whose dose rate you know and it finds the sensitivity of your own tube (default: 180 counts per minute for 1 µSv/h).
Raw pulse counter, identity, calibration and clock over a USB serial line, documented and open. This is what the monitor reads.
One file per language. Pick yours:
.bin file of your language onto it.The BOINC part of Yarrow is a small program that uses almost no CPU. It looks for a counter every 15 seconds, cuts the pulse counter into exact bins and sends them as BOINC trickles. A bin is only kept when it is exact: both edges read in the right second, the tube voltage on the whole time, the counter not restarted, the clock not jumped. Nothing is ever estimated or padded. Builds for Windows (x64, x86, ARM64) and Linux (x86-64, ARM64, ARMv7).
| Counter | Connection | State |
|---|---|---|
| FNIRSI GC-03 + Yarrow | USB serial | Available |
| Radioactive@Home USB counter (SBM-20; boards 2.01 to 2.60, the kit, and 3.01) | USB HID | Available |
| GQ GMC-300 / 320 / 500 / 600 | USB serial | Available |
The rule for every counter stays the same: only raw pulse counts from the tube are accepted, never a rate the counter has smoothed itself.
Yarrow Hub works on its own, without BOINC. It shows the live dose rate of your counter, keeps your history on your computer, draws graphs and statistics, shows the dose in nSv/h, µSv/h or µrem/h, rings an alarm at levels you choose and exports CSV. It runs with the FNIRSI GC-03 and with the Radioactive@Home counters. With a GC-03 it also sets the clock, calibrates the tube and installs firmware.
A network of home instruments needs to trust its numbers, and Yarrow cannot lock a volunteer's computer. So it makes the checks that fake or broken data cannot pass.
Impossible bins are refused at once: a dose rate over 1,000 µSv/h, data from the future or the distant past, an impossible dead time or sensitivity.
A day later each stream is tested. Real counts are random, so their spread must match Poisson statistics. A made-up constant is too smooth and fails.
Every detector has its own identity from its chip number. A copy of another detector's counts, a recorded day sent again or a dose rate far from the city's other detectors is held and looked at. New detectors earn a part of the credit that grows with a consistent history; up to 5 detectors per volunteer, a daily cap.
The map shows the median of a city, so one wrong detector cannot move it. Credit comes only after the checks.
Every valid bin is worth 10 credits (up to 150 bins per detector per day), granted about a day after the data arrived, once the checks are passed.
A point on the map is a city, the name you type in your preferences. Nothing finer than a city is ever sent or shown: no address, no GPS, no street. The volunteers table shows BOINC user names and amounts, never places. City positions come from GeoNames (CC BY 4.0), the world map from Natural Earth (public domain).
On Linux the BOINC client runs as its own user and may not open USB devices, so the task says No detector found although a test program finds the counter. One command lets BOINC open the counters Yarrow reads (it only touches those):
curl -fsSL https://raw.githubusercontent.com/alplix/yarrow/main/linux/yarrow-linux-setup.sh | sudo sh sudo systemctl restart boinc-client
Then unplug the counter and plug it in again. Works the same on Raspberry Pi OS. More details and what to look for in the task log: docs/linux.md.
Practically not. The monitor reads a counter about once a second and sends a small message every ten minutes.
Anywhere that stays the same, a shelf or a desk is fine. Move it rarely, the building and the surroundings are part of the reading.
That is normal: ground, building and tube differ, and one detector has a counting noise of several percent. Compare the 24-hour or 7-day value and read the pattern.
About 50 to 200 nSv/h. Granite and some volcanic rocks, stone buildings and high altitude raise it.
No. It is information from volunteers' hobby instruments. For official information follow your national authority.
Yes. Besides the FNIRSI GC-03 the monitor reads the USB counters of the old Radioactive@Home project (no flashing needed) and the GQ GMC family. Only raw pulse counts are accepted. Tell us what you have: a new counter is one small driver away.
Yes. The original bootloader and the factory tube calibration are never touched; copy the original file the same way.