Overview
DX Map shows real-time HF propagation conditions based on actual reception reports and ionospheric measurements. It helps amateur radio operators identify which bands and paths are currently open for communication.
WSPR and NCDXF data updates every 15 minutes. Ionosonde data updates every 10 minutes. The page auto-refreshes every 5 minutes.
Data Sources
WSPR Weak Signal Propagation Reporter
- What: Thousands of low-power digital beacons worldwide
- Bands: 80m, 40m, 20m, 15m, 10m
- Update: Every 15 minutes
- Best for: Overall band conditions, path discovery
NCDXF International Beacon Project
- What: 18 synchronized 100W beacons at strategic locations
- Bands: 20m, 17m, 15m, 12m, 10m
- Update: Every 15 minutes
- Best for: SSB path assessment (calibrated 100W reference)
Ionosondes Direct Ionospheric Measurements
- What: Ground-based radar stations that measure the ionosphere directly
- Data: MUF(3000) — Maximum Usable Frequency for 3000km paths
- Update: Every 10 minutes (via KC2G)
- Best for: Understanding ionospheric conditions at specific locations, predicting band openings
DX Cluster Real-time SSB Spot Network
- What: Global network of operators reporting DX stations they hear
- Data: SSB spots filtered by frequency (voice segments only)
- Update: Real-time (via VE7CC)
- Best for: Seeing where SSB activity is happening right now
Which to use? WSPR gives broad coverage across many paths. NCDXF beacons provide consistent 100W reference signals for SSB path assessment. Ionosondes show underlying ionospheric conditions. DX Cluster spots show where real SSB activity is happening right now.
DX Index
The DX Index shows how current conditions compare to what's typical for this time of day. An index of 50 means normal (1.0x typical); higher is better.
Index Scale
Paths below Good threshold are not displayed.
SSB Outlook
The SSB column (NCDXF only) estimates how likely a voice QSO is on that path, based on how many stations hear the beacon and how strong the signals are.
SSB Outlook Scale
A path needs both wide coverage (multiple skimmers) and strong signals (high SNR) to rate "Strong". A beacon with high SNR but only one skimmer won't rate well — that could be a localized fluke, not reliable propagation.
Cluster Spots (WSPR View)
In WSPR view, the SSB and Spots columns show real-time SSB activity from the DX Cluster network. This tells you where operators are actually making voice contacts right now.
SSB Outlook (WSPR)
Spots Column
Shows the count of SSB spots from the DX Cluster in the last 60 minutes for this corridor (e.g., all EU-NA spots, not just this specific grid path).
- • Spots are aggregated by corridor (EU-NA, NA-SA, etc.)
- • If F4CXO in France works US East, ALL EU-NA paths show this activity
- • Only voice frequencies are counted (beacon frequencies excluded)
- • Data sourced from VE7CC DX Cluster
Tip: Spots are corridor-aggregated: if anyone in EU is working NA on a band, you'll see that activity on ALL EU-NA paths. This answers the real question: "Is anyone working EU-NA on 15m right now?" — not just the specific grid pair.
Band Score
Band Score (NCDXF only) combines signal strength with how many stations hear the beacon. Higher score = stronger, more reliable path.
Score Scale
Best Band Indicator
Each corridor button shows which band currently has the highest DX Index (WSPR) or Band Score (NCDXF) for that path. This helps you quickly identify where to tune.
Reading the Indicators
The best band updates in real-time as conditions change. During history playback, you'll see how the optimal band shifts throughout the day.
Trend Indicators
Arrows next to the Index (WSPR) or Score (NCDXF) show how the path is changing compared to one hour ago. This helps you decide whether to call now or wait.
Trend Symbols
Hover over the arrow to see the previous value. A rising path (↑) with good conditions is ideal — you're catching the opening. A falling path (↓) may still be workable but consider calling sooner rather than later.
Solar Indices
The header bar shows current space weather conditions that affect HF propagation.
Kp Index (Geomagnetic Activity)
Higher Kp = worse HF conditions, especially on polar paths.
SFI (Solar Flux Index)
Indicates solar activity. Higher = better conditions on higher bands (10m-20m).
Solar Wind Velocity
High speeds can trigger geomagnetic storms.
DRAP (D-Region Absorption)
Highest Affected Frequency (HAF) for the sunlit hemisphere. Frequencies below this value suffer 1dB+ absorption from solar flares. Affects only sunlit paths.
Example: 30 MHz means all HF bands are degraded on sunlit paths.
Ionosondes
Ionosondes are ground-based radar stations that measure the ionosphere directly by sending radio pulses upward and analyzing the reflections. Click the Ionosondes button to display real-time MUF readings from stations worldwide.
What is MUF(3000)?
MUF(3000) is the Maximum Usable Frequency for a 3000km path. It indicates the highest frequency that will be reflected back to Earth at that location. Higher MUF means higher bands are open.
Data source: Ionosonde data is provided by KC2G, which aggregates readings from GIRO (Global Ionospheric Radio Observatory) stations. Only stations with confidence ≥50% and readings less than 2 hours old are displayed.
Note: Ionosonde markers are only displayed in 2D map view.
MUF Map Overlay
The MUF Map button displays an interpolated heatmap showing estimated MUF values across the globe. This provides a visual overview of ionospheric conditions beyond just the ionosonde station locations.
Color Scale
Purple/blue indicates low MUF (nighttime, polar regions), while green/yellow indicates high MUF (daytime, equatorial regions). The overlay updates every 10 minutes.
Opacity Control
When the MUF Map is enabled, an opacity slider appears in the legend panel (bottom-right of the map). Adjust it to balance visibility of the heatmap with the underlying map details.
How it works: The overlay is generated by interpolating MUF readings from all available ionosonde stations using radial basis function (RBF) interpolation. Areas far from any station may be less accurate. The ionosonde marker colors match the overlay gradient for easy comparison.
Note: MUF Map overlay is only displayed in 2D map view.
Reading the Map
Arc Colors (by Band)
Path arcs are colored by band — green for higher frequencies, red/purple for lower:
Arc Thickness (by Quality)
Thicker arcs indicate better propagation quality (higher DX Index or Band Score). This lets you quickly identify the strongest paths at a glance.
Path Labels
Each path shows a label at its midpoint with the DX Index (WSPR) or Band Score (NCDXF). The label background color matches the band color for easy identification.
Path Endpoints
Endpoint labels show the location name (e.g., "Central Europe", "US East Coast"). Click any endpoint label to filter to all paths from/to that location. Click again to deselect. Your selection persists when changing band or region filters.
Grayline (Day/Night)
Toggle the grayline overlay to see the day/night terminator. A yellow sun marker shows the current subsolar point. The grayline zone often provides enhanced propagation as the ionosphere transitions between day and night states.
Filtering
- Region: Filter by corridor (e.g., EU-NA, EU-AS). Each button shows the best band and a colored dot for path quality.
- Band: Show only specific bands
- Click a row: Highlight that specific path on the map. Click again to return to your previous view.
- Hover a row: The path animates on the map with flowing dashes
- Click endpoint: Filter to all paths from/to that location
Endpoint selection is "sticky" — it persists when changing bands or regions, and auto-clears only if no matching paths exist.
Table Sorting
- Click column header: Sort by that column
- Click again: Toggle ascending/descending
- Sortable columns: From, To, Region, Band, Index/Score, SNR, Skimmers, SSB
Default sort groups paths by transmitter and shows highest index first.
3D Globe View
Click the 3D Globe button (top-right of map) to switch to an interactive 3D visualization. The globe provides a more intuitive view of great-circle paths and global propagation patterns.
Globe Features
- Arc colors: Same band colors as 2D map (10m green → 80m purple)
- Arc thickness: Thicker = higher quality (scales with zoom level)
- Day/night terminator: Shows current grayline with sun position marker
- Auto-rotation: Globe slowly rotates until you interact with it
- Click paths: Click arcs or endpoints to filter, same as 2D map
Navigation
- Drag: Rotate the globe
- Scroll: Zoom in/out
- Hover: Shows path details tooltip
Tip: The 3D globe is especially useful for visualizing polar and transpolar paths that appear distorted on flat maps. Arc thickness automatically adjusts as you zoom — thicker when zoomed in, thinner when zoomed out.
Note: Ionosonde markers and MUF Map overlay are only available in 2D map view. These buttons are hidden when viewing the 3D globe. Grayline (day/night terminator) works in both views.
History Playback
Use the controls at the bottom of the map to review the past 48 hours.
- ▶ Play: Animate through history
- 1x / 2x: Toggle playback speed (1 or 2 frames per second)
- Slider: Drag to jump to a specific time
- LIVE: Return to real-time data
The header badge shows LIVE for real-time data, HISTORY during playback, DELAYED if data is >15 min old, or STALE if >1 hour old.
What Updates During Playback
All map features update to show historical values: path data, filters, grayline, best band indicators, solar indices, ionosonde markers, the MUF map overlay, and the 3D globe. This lets you see how ionospheric conditions evolved alongside actual propagation.
DX Chat
Connect with other amateur radio operators using the built-in chat. Click the blue chat bubble in the bottom-right corner to open the chat panel.
Getting Started
- Enter your callsign to join the chat
- Your callsign is validated (must be a valid amateur radio format)
- Click "X online" to see who's currently connected
- Click any callsign in the user list to view their QRZ page
Features
- Real-time messaging with other DX Map users
- Message history preserved (last 100 messages)
- Unread message badge when chat is closed
- Chat automatically hides in fullscreen mode
- Press Escape to close the chat panel
Keyboard Shortcuts
Control the map quickly using your keyboard.
Playback
Display
Fullscreen Mode
Fullscreen mode shows the map with a compact solar indices bar (Kp, Solar Wind, SFI, DRAP) at the top-left. Overlay toggle buttons (Grayline, Ionosondes, MUF Map) appear at the top-right, along with the 2D/3D toggle and Exit button. Playback controls remain at the bottom. Press F or click the Fullscreen button to toggle.
Operating Tips
For SSB/Phone
- • In WSPR view: "Strong" or "Moderate" cluster spots = active SSB on this path
- • "No Spots" with high Index = band open but no one calling — be first!
- • In NCDXF view: Look for "Strong" or "Moderate" SSB outlook
- • Check that Index is ≥80 for reliable two-way communication
For CW
- • CW works with weaker signals — "Weak" SSB outlook may still be workable
- • Index 50+ is usually sufficient for CW contacts
- • Single-skimmer paths can still yield QSOs for skilled ops
For Digital (FT8/FT4)
- • Digital modes work even with "Unlikely" SSB outlook
- • Any visible path on the map is potentially workable
- • WSPR data directly indicates digital-mode band conditions
During Geomagnetic Storms (Kp 5+)
- • High-latitude paths (polar, transatlantic) degrade first
- • Equatorial paths often remain open
- • Lower bands (40m, 80m) may be more stable than 20m+
- • Watch for post-storm enhancement 12-24 hours after Kp drops