Propagation Beacons and WWV: Free Tools for Checking Band Conditions

You're staring at a quiet band. No signals. Is propagation dead, or is everyone just asleep? Before you call CQ into the void for 20 minutes, you've got free tools that tell you exactly what the ionosphere is doing right now. Not predictions. Not forecasts based on sunspot numbers from yesterday. Actual, real-time RF propagation data.

The NCDXF/IARU International Beacon Network

This is the most underused tool in amateur radio. Eighteen beacons spread across every continent, transmitting continuously on five frequencies, on a synchronized schedule. Free. Always there. And most hams don't even know about it.

The Northern California DX Foundation (NCDXF) and IARU maintain beacons at these locations:

• 4U1UN — United Nations, New York
• VE8AT — Eureka, Canada
• W6WX — California, USA
• KH6RS — Hawaii
• ZL6B — New Zealand
• VK6RBP — Australia
• JA2IGY — Japan
• RR9O — Novosibirsk, Russia
• VR2B — Hong Kong
• 4S7B — Sri Lanka
• ZS6DN — South Africa
• 5Z4B — Kenya
• 4X6TU — Israel
• OH2B — Finland
• CS3B — Madeira
• LU4AA — Argentina
• OA4B — Peru
• YV5B — Venezuela

Each beacon transmits sequentially on 14.100, 18.110, 21.150, 24.930, and 28.200 MHz (all in CW). The transmission cycle lasts exactly three minutes for all 18 beacons to complete one rotation on one frequency. Each beacon transmits for 10 seconds: its callsign at 22 WPM followed by four one-second dashes at 100W, 10W, 1W, and 0.1W.

Here's why the power stepping matters. If you hear the callsign and all four dashes clearly, propagation on that band to that part of the world is wide open. Hear the callsign and two dashes? Moderate propagation. Only catch the 100W dash faintly? Band is barely open in that direction. Hear nothing from a beacon that's usually S9? Band is closed to that path.

The three-minute rotation means you can assess propagation to multiple continents in under 10 minutes without transmitting a single watt.

Practical use: I keep 14.100 MHz programmed into a memory slot on my IC-7300 with a narrow CW filter (250 Hz bandwidth). When I sit down at the radio, first thing I do is punch that memory and listen for a few minutes. If I'm hearing VK6RBP or ZL6B from the US East Coast on 20 meters, I know long-path is working. If JA2IGY is booming, short-path Pacific is open. It takes all the guesswork out of band selection.

The schedule is synchronized to UTC. You can find the exact timing table at ncdxf.org/beacon — it tells you which beacon is transmitting at any given second. Match what you hear against the schedule to identify which beacon you're copying.

WWV and WWVH: Your Propagation Bulletin on the Hour

WWV (Fort Collins, Colorado) and WWVH (Kauai, Hawaii) are NIST time stations broadcasting continuously on 2.5, 5, 10, 15, 20, and 25 MHz. Most hams know them for time signals, but they also broadcast a geophysical alert at specific minutes past each hour.

The propagation-relevant broadcast:

• WWV: Minutes 18 past each hour
• WWVH: Minutes 45 past each hour

The bulletin includes:

• Solar flux index (SFI): Higher = better HF propagation. Values range from about 65 (solar minimum) to 250+ (solar maximum). Above 100 means 10 and 12 meters might be open. Above 150 and higher bands get interesting.
• A-index and K-index: Geomagnetic disturbance levels. K-index is 3-hourly (0-9 scale), A-index is daily (0-400). K≤2 is quiet, good for HF. K≥5 means a geomagnetic storm is happening, and HF propagation (especially on paths over the poles) may be severely degraded or blacked out.
• Space weather alerts: Proton events, solar flares, geomagnetic storm warnings.

The voice bulletin sounds something like: "Solar-terrestrial indices for 18 July from Boulder... Solar flux 156, estimated planetary A-index 8, estimated planetary K-index 2..."

What this tells you in plain terms: SFI of 156 means the sun is active enough to ionize the upper atmosphere well — even 10 meters might be open during daylight hours. A-index of 8 and K-index of 2 mean the geomagnetic field is quiet, so no storm-related absorption or blackouts. Good day to be on HF.

When you should worry: K-index hits 5 or above. That's a minor geomagnetic storm. High-latitude paths (US to Europe via great circle, anything polar) degrade first. Equatorial paths (US to South America, for instance) usually survive longer. If you're hearing good signals on 40 and 80 meters during what should be dead daytime hours, that's actually a bad sign — it often means the higher bands are being absorbed and energy is reflecting from lower layers.

I got caught by this once. Early in my HF career, I heard 80 meters full of signals at 2 PM local time and thought "great conditions!" Nope. It was a geomagnetic storm. The higher bands were completely dead. The 80-meter signals were coming from a few hundred miles via NVIS (Near Vertical Incidence Skywave), not any kind of DX propagation. Lesson learned.

WSPR: The Crowd-Sourced Propagation Map

WSPR (Weak Signal Propagation Reporter, pronounced "whisper") isn't a beacon network in the traditional sense — it's a distributed network of hundreds of transmitting and receiving stations worldwide, all running automated low-power signals and reporting what they hear to a central database.

WSPR stations transmit on specific frequencies within each band:

• 3.5946 MHz (80m)
• 7.0386 MHz (40m)
• 10.1387 MHz (30m)
• 14.0956 MHz (20m)
• 18.1046 MHz (17m)
• 21.0946 MHz (15m)
• 24.9246 MHz (12m)
• 28.1246 MHz (10m)

Transmissions are 110.6 seconds long, narrow bandwidth (~6 Hz), and typically run at 200 mW to 5W. The WSPR protocol can decode signals at -28 dB below the noise floor. This means WSPR will show propagation paths that are too weak for voice or even FT8 contacts — it's detecting the first faint hints that a band is opening.

How to use it without transmitting: Go to wsprnet.org and look at the map. Filter by band and time. If you see WSPR spots on 10 meters between your region and, say, South Africa, there's propagation on that path. Might be weak — WSPR decode doesn't guarantee you'll make a voice contact — but the band isn't completely dead.

The real power is pattern recognition over time. Check WSPR maps for the same band at the same time of day over a week. You'll start seeing the propagation rhythms — when paths open and close, which bands peak at which hours. It's like having hundreds of automated propagation monitors working for you constantly.

PSKReporter and the Reverse Beacon Network

Two more free tools that complement the beacons:

Reverse Beacon Network (RBN): A network of automated CW and RTTY skimmer stations. Every time you call CQ in CW, dozens of skimmers decode your signal and report your SNR. Even if you're not a CW operator, you can watch the RBN to see who's hearing what. If skimmers in Europe are decoding US stations on 15 meters, the band is open. Check it at reversebeacon.net.

PSKReporter (pskreporter.info): Same concept but for digital modes. Decoded FT8 and FT4 signals are reported by the many stations running WSJT-X or similar software with reporting turned on. The map shows real-time propagation based on actual signals being decoded worldwide. It's the most comprehensive propagation picture available because FT8 is everywhere now.

A thread on the QRZ forums had someone compare propagation predictions from VOACAP against actual PSKReporter data over a month. The prediction software was roughly 65% accurate for general trends but frequently wrong about specific path openings and timing. Real-time tools like PSKReporter caught openings that models missed entirely.

Building a Propagation Checking Routine

Here's my quick routine before an operating session, takes about 5 minutes:

1. Check WSPR map for the band I want to operate (30 seconds)
2. Tune to 14.100 MHz and listen for beacons — which continents am I hearing? (2-3 minutes)
3. Glance at PSKReporter for the target band to see real-time activity (30 seconds)
4. If things look promising, call CQ. If not, try a different band or wait.

That's it. No apps, no subscriptions, no paid services. All free infrastructure maintained by the amateur radio community.

Solar Cycle Context

All of this data is more useful when you understand where we are in the solar cycle. We're currently in Solar Cycle 25, which began in December 2019 and (as of mid-2024) has been exceeding initial predictions. Solar flux has regularly been above 150, meaning the higher HF bands (10, 12, 15 meters) are seeing excellent propagation during daylight hours.

During solar minimum (last one was 2019-2020), the beacons on 28.200 MHz will be silent for days. Only 20m and lower bands are reliably open. During solar maximum (which we're approaching now), you might hear beacons on 28.200 MHz from all over the world during a single rotation. The difference is dramatic.

Smartphone Apps That Aggregate This Data

If you want all this in your pocket:

• HamClock (free, runs on Raspberry Pi or desktop): Shows solar indices, band conditions, DXCC paths, grey line, and more on a single display
• Solar Ham (solarham.net, also has an app): Real-time solar data, X-ray flux, proton events
• DX Propagation (various apps): Pulls SFI/K-index and gives band-by-band estimates

But nothing replaces actually listening. Apps and websites give you the conditions — beacons and WSPR tell you what's actually making it through the ionosphere to your specific antenna at your specific location. Your antenna, your terrain, your local noise floor — that's what matters.