The Instrument — the Great Falls node's day

One Nooelec NESDR SMArt v5 (RTL2832U + R820T2) (bare dongle) in Great Falls, MT (city-level), sweeping band table v4 (19 cells, 7 retired) — 0 captures over 0 h today, 5 days so far since 2026-08-27; last capture 2026-08-30 17:34:01 MT. The receiver was NOT present at the last pass. Snapshot as of 2026-08-31; every picture below is a still of committed data, never a mock.

In plain English

This page is the engine looking at its own antenna. A cheap software-defined radio in Great Falls sweeps a frozen table of frequency cells — time-signal beacons (WWV, CHU), shortwave broadcast bands, FM, air band and two reference cells that should never change — and keeps every capture's spectrum.

The point is not the pretty picture. It is a day-by-day record of how well the sky carried known signals over known distances, so that in ninety-plus days a pre-registered test can ask whether there is any rhythm in it that a simple rule cannot explain.

What you'll see: A home receiver becomes a calibrated ruler for the ionosphere — and its daily calls beat the coin they start as.

ionospheric

control

reference

capture2026-08-30 17:34 MT · 131/131

hfq:wwv109.950 – 10.045 MHz · 20 bins × 5.0 kHzband table v4 · 131 captures

Spectrum — one capture; click to tune

Waterfall — the day, newest at the bottom; click a column to tune, a row to scrub

colour = dB, per-cell floor 20 → ceiling 45 dB (5th / 99th percentile)still image of 130 captures — it moves only when a newer snapshot lands

Scan mode0 bins ≥ floor+6 dB in the latest capture · floor 15.8 dB

no cards yet — start the sweep or step

Confidence: heuristic, not a classifier — “carrier-like” means the peak is at most 2 bins wide, “broadband” means wider; nothing here identifies a station. The bar for signal fingerprinting is on Discover.

▸Learn more

The spectrum is power against frequency for one capture of one cell; the dashed line is the floor (the median bin), and ticks mark bins at least 6 dB above it. The waterfall stacks every capture of the last 24 h so a station switching on shows as a vertical streak. dB values are the receiver's own uncalibrated scale — compare within a cell, not across days or receivers. Clicking sets a "tuned" marker only; this page does not play audio.

Receivers

Receiver	Role	USB serial	Since	On the bus
Great Falls, MT (city-level)	primary	51101514	2026-08-27	no
Great Falls, MT — HF antenna (city-level)	hf	50469530	2026-08-30	yes

Each pass selects its dongle by USB serial, never by enumeration order. Both receivers sit at the same site, so they are an antenna A/B and an instrument-drift control — not the two-site baseline the strong ionospheric claim still needs. A rhythm on both is the sky; a rhythm on one is that chain.

Each cell's day 2026-08-31

no daily rows yet

Frozen calls

20 frozen · 14 gradedBrier 0.250 vs null 0.2504 classes · as of 2026-08-31

question	p	null	frozen	target	outcome	brier
fof2upWill IF843's latest foF2 tomorrow be higher than today's latest?	0.50	0.50	2026-08-31	2026-09-01	open	—
inv2Will the 12Z Great Falls sounding tomorrow show a lowest-3-km inversion >= 2 K?	0.50	0.50	2026-08-31	2026-09-01	open	—
skip10Will hf:ham10m show >= 1 station (median over daylight captures) tomorrow?	0.50	0.50	2026-08-31	2026-09-01	open	—
wwv20Will the WWV 20 MHz carrier reach >= 3 dB over floor at any capture tomorrow?	0.50	0.50	2026-08-31	2026-09-01	open	—
fof2upWill IF843's latest foF2 tomorrow be higher than today's latest?	0.50	0.50	2026-08-30	2026-08-31	yes	0.250
inv2Will the 12Z Great Falls sounding tomorrow show a lowest-3-km inversion >= 2 K?	0.50	0.50	2026-08-30	2026-08-31	yes	0.250
skip10Will hf:ham10m show >= 1 station (median over daylight captures) tomorrow?	0.50	0.50	2026-08-30	2026-08-31	open	—
wwv20Will the WWV 20 MHz carrier reach >= 3 dB over floor at any capture tomorrow?	0.50	0.50	2026-08-30	2026-08-31	open	—
fof2upWill IF843's latest foF2 tomorrow be higher than today's latest?	0.50	0.50	2026-08-29	2026-08-30	yes	0.250
inv2Will the 12Z Great Falls sounding tomorrow show a lowest-3-km inversion >= 2 K?	0.50	0.50	2026-08-29	2026-08-30	yes	0.250
skip10Will hf:ham10m show >= 1 station (median over daylight captures) tomorrow?	0.50	0.50	2026-08-29	2026-08-30	yes	0.250
wwv20Will the WWV 20 MHz carrier reach >= 3 dB over floor at any capture tomorrow?	0.50	0.50	2026-08-29	2026-08-30	yes	0.250
fof2upWill IF843's latest foF2 tomorrow be higher than today's latest?	0.50	0.50	2026-08-28	2026-08-29	no	0.250
inv2Will the 12Z Great Falls sounding tomorrow show a lowest-3-km inversion >= 2 K?	0.50	0.50	2026-08-28	2026-08-29	no	0.250
skip10Will hf:ham10m show >= 1 station (median over daylight captures) tomorrow?	0.50	0.50	2026-08-28	2026-08-29	yes	0.250
wwv20Will the WWV 20 MHz carrier reach >= 3 dB over floor at any capture tomorrow?	0.50	0.50	2026-08-28	2026-08-29	yes	0.250
fof2upWill IF843's latest foF2 tomorrow be higher than today's latest?	0.50	0.50	2026-08-27	2026-08-28	yes	0.250
inv2Will the 12Z Great Falls sounding tomorrow show a lowest-3-km inversion >= 2 K?	0.50	0.50	2026-08-27	2026-08-28	yes	0.250
skip10Will hf:ham10m show >= 1 station (median over daylight captures) tomorrow?	0.50	0.50	2026-08-27	2026-08-28	yes	0.250
wwv20Will the WWV 20 MHz carrier reach >= 3 dB over floor at any capture tomorrow?	0.50	0.50	2026-08-27	2026-08-28	yes	0.250

▸Learn more

Each row is a probability frozen the day before its target and graded by arithmetic from the receiver's own record. The model is a fixed rule (persistence blended with a trailing base rate), shrunk to 0.5 while the base has fewer than 10 days — so for now (5 days frozen) every p is an honest coin, and the Brier score measures the coin, not a forecaster. Nothing here is advice and nothing feeds skywatch.

▸What do these words mean?

Spectrum — Signal strength plotted against frequency at one instant. A peak is a station; the flat floor between peaks is the noise the receiver hears when nothing is there.

Waterfall — A picture of radio over time: each row is one moment's spectrum, colour is strength, and rows scroll down like water. Signals show as vertical streaks; you can see a band open or a broadcaster sign on.

SDR (software-defined radio) — A receiver where the radio work happens in software: a small USB stick digitises a wide slice of the spectrum and a computer does the tuning and decoding. Ours is a Nooelec NESDR SMArt v5 in Great Falls, Montana.

Carrier — The steady, unmodulated tone a transmitter sits on. A time-signal station's carrier is a clean, constant line in the spectrum, which makes it a perfect thing to measure day after day.

Beacon — A transmitter that sends a known signal from a known place on a schedule, so anyone can use it as a ruler. WWV (Colorado), WWVH (Hawaii) and CHU (Ottawa) are time-signal stations we use exactly this way.

dB (decibel) — The decibel, a logarithmic unit for comparing power. +3 dB is double, +10 dB is ten times, +20 dB is a hundred times. Radio uses it because signals span an enormous range.

SNR (signal-to-noise ratio) — How far a signal stands above the background hiss, in decibels. 0 dB means signal and noise are equal; each +10 dB is ten times the power. WSPR decodes down to about −30 dB — well below what an ear could hear.