How to use TropoScout

1. Quick start

1. Enter your station locator in TX (Home) QRA and press Set.
2. Choose the forecast Radius. 5000 km is the maximum; 2500 km is the default.
3. Choose PROPAGATION for the normal TropoScout model, or SCATTER (EXP) to examine the experimental turbulent-boundary proxy.
4. Choose the CLASSIC map palette or the higher-saturation VIVID palette. Use GRID ON if you want large 4-character Maidenhead squares over the map.
5. Select the amateur band you want to examine.
6. Stay in LIVE for the normal forecast timeline, or choose HISTORY to recall a recent GFS analysis.
7. In LIVE, move the forecast slider, use the 3-hour step buttons, press NOW, or press PLAY.
8. Click the map or enter an RX QRA to analyse a path.
9. Optionally enable BEACONS and/or ATV markers for the selected band.

2. Top controls

3. Forecast models

The Model selector keeps two atmospheric interpretations side-by-side without blending them together.

Experimental means experimental. NOAA GFS can show the large-scale environment in which turbulent mixing may form, but its 0.25° grid does not resolve individual turbulent eddies. TropoScout therefore does not claim that SCATTER (EXP) detects turbulence or predicts received RF power.

SCATTER (EXP) deliberately has no amateur-band frequency weighting in this first release. The proposed scattering physics depends on turbulent structure size relative to wavelength, and that structure size is not available from GFS. The selected band still controls beacons/ATV and the separate path-engineering calculations.

The experimental model is based on the meteorological environment described in WB2FKO's paper, Tropospheric Forward Scattering as an Alternative Explanation for Long-Distance VHF/UHF Propagation.

4. Reading the forecast map

The coloured overlay represents the currently selected atmospheric model derived from NOAA/NCEP GFS data. The underlying map is intentionally monochrome so the forecast colours remain visible. Use Palette to switch between the established Classic colours and the Vivid scale; the forecast score itself does not change.

In PROPAGATION mode the scale is Normal / Enhanced / Good / Strong / Exceptional. In SCATTER (EXP) it changes to Low / Moderate / Elevated / Strong / Very high. Both are qualitative opportunity scales rather than received-signal predictions.

A faint dashed circle marks the selected TX forecast radius. You can pan the map globally, but live forecast/path analysis is limited to the selected radius. The 5000 km option is intended for very wide-area monitoring; the underlying NOAA GFS grid resolution is unchanged, so zooming farther out does not add atmospheric detail.

5. LIVE / HISTORY retrospective analysis

LIVE shows the normal current GFS forecast timeline. HISTORY recalls a previous GFS analysis (+00), allowing a known propagation opening or path to be examined retrospectively with the same TropoScout atmospheric calculations.

1. Set the required TX QRA and radius.
2. Select HISTORY in the Time control.
3. Choose a UTC date and one of the 00Z, 06Z, 12Z or 18Z cycles.
4. Press LOAD. The first uncached request can take longer while the regional analysis is downloaded and processed.
5. Select an RX/path normally to inspect historical path diagnostics. Choose LIVE to return to the current forecast.

v1.1.2 range: the most recent 30 days at 0.25° GFS resolution. Recent analyses use the fast NOMADS regional filter; older analyses within that window automatically fall back to NOAA NODD/AWS. If a particular cycle is absent, TropoScout reports a short error and keeps the previous LIVE map correctly labelled. Historical operator views are cached separately and do not add reception reports or training rows to the research database.

6. Forecast time and playback

Forecast +xh shows the model forecast hour and the full valid UTC date/time. In v1.0.19 this timestamp is deliberately larger so the forecast frame is easier to identify at a glance. Use the slider to move through the available 3-hour frames.

• ◀ 3h / 3h ▶ — move one forecast frame.
• NOW — jump to the forecast frame nearest the current time.
• PLAY — animate forward through the forecast.
• Speed — choose a 2-second, 4-second or 8-second delay between forecast frames; 4 seconds is the default.
• Loop — restart at the beginning when the last frame is reached.

Playback speed can be set to 2 s, 4 s or 8 s; 4 s is the default. In PROPAGATION mode TropoScout keeps up to three future overlays warm. SCATTER (EXP) deliberately keeps only the immediate next frame warm to reduce browser decode pressure. A loaded PNG is considered ready on browser image load; decode is best-effort and a stale preload times out so it can be retried. Rendered overlays are cached on the VPS NVMe, so revisiting a band/hour is normally much faster. If a frame is still being prepared, the previous frame remains visible until the new one is ready.

7. Beacons and ATV repeaters

The BEACONS and ATV buttons show stations for the currently selected band and within your selected TX radius. The button text also shows selected-band and overall counts.

Beacon data come from BeaconSpot / UK Microwave Group only. TropoScout no longer merges IARU, TU Dresden, RSGB/ETCC, REF, WIA/VK, VHF.NZ/ZL, G0LGS or local beacon files into the live layer, avoiding stale records from secondary caches. The BeaconSpot feed is refreshed daily and filtered by the selected band and TX radius.

ATV repeater data are merged from the current national/community sources used by TropoScout: UK RSGB/ETCC, Netherlands VERON and Belgium UBA, plus ATV-RepeaterMap.com / DL5BCA as a European supplementary source covering German, UK, Dutch, Belgian and Swiss systems. Overlapping entries are merged and operator-confirmed local corrections are applied afterwards. Click a beacon or ATV marker to view its details and use it as the RX path endpoint.

ON4KST stations

The compact KST login controls sit at the far right of the main operator row, immediately after the antenna POL selector. Enter your ON4KST callsign and password, choose a room (Microwave is the default), and press Connect.

After ON4KST accepts the login, TropoScout polls the room user list using the same classic /SH US method used by the DXLog KST Bridge. The KST map-layer button is enabled automatically and current room users with valid Maidenhead locators are drawn on the map.

Click a KST station and choose USE RX to use that station's advertised locator as the normal TropoScout RX endpoint. SET A and SET B select two KST endpoints without changing your normal TX→RX forecast path. When both are selected, press PLOT in the A–B panel to draw the station-to-station line, show QRB/QTF and zoom the map to the pair. Changing A or B removes the previous line until PLOT is pressed again.

Credentials: TropoScout never stores the KST password in browser storage, files, logs or the research database. The VPS holds it only long enough to complete the classic ON4KST login and discards it immediately after sending it. ON4KST's classic port 23000 service is Telnet, so the VPS→ON4KST leg is a legacy unencrypted connection.

8. Selecting and clearing a path

A path can be selected by entering an RX QRA, clicking a map position, or clicking a beacon/ATV marker. The right-hand panel then shows the selected TX/RX, distance, bearing, atmospheric path result and engineering information.

The path must remain inside the active forecast radius. Use Clear beside RX to remove it and return the map to the TX station view.

9. Band forecast / scatter components

TropoScout supports 6 m, 4 m, 2 m, 70 cm, 23 cm, 13 cm, 9 cm, 6 cm and 3 cm. In PROPAGATION mode the selected band weights the forecast overlay. In SCATTER (EXP) the meteorological overlay is frequency-neutral; the band still controls beacons/ATV repeaters and the separate path-engineering calculations.

Once an RX path is selected, PROPAGATION mode compares opportunity across all supported bands. In SCATTER (EXP), this card instead explains the experimental score using inversion strength, refractive anomaly, wind shear, thermal-front strength, moisture contrast, vertical motion and boundary/PBL height. The experimental score is not frequency weighted.

10. Propagation / scatter detail and path diagnostics

In PROPAGATION mode, Path duct plots the strongest diagnosed trapping layer along the great-circle route. In SCATTER (EXP), the tab becomes Scatter layer and plots the strongest candidate turbulent boundary plus the GFS planetary-boundary-layer height.

Coverage describes how much of the path is associated with diagnosed trapping/enhanced conditions. A strong middle section can be useful even when the duct is not continuous from TX to RX, so TropoScout distinguishes path topology rather than reducing everything to one yes/no result.

11. Terrain, Fresnel and path engineering

Select an RX path and open the Terrain tab. TropoScout uses Copernicus DEM GLO-90 elevation data. RADIO EARTH is the normal engineering view and includes the 4/3-effective-Earth bulge used by the path calculations. FLAT EARTH is a display-only alternative that removes Earth curvature from the plotted terrain so individual ridges and obstructions around the radio horizon are easier to identify, especially on UHF and microwave paths.

In FLAT EARTH view, TX H and RX H mark the smooth 4/3-Earth radio-horizon distances from each terminal. The raw terrain, straight TX-to-RX line and 60% first-Fresnel reference remain visible. Switching the display does not change propagation, diffraction, P.2001 or any other engineering calculation.

The terrain view/engineering panel can show direct-ray clearance, first Fresnel-zone clearance, 60% F1 clearance, separate TX/RX radio-horizon distances, dominant obstruction, free-space path loss, a simple diffraction estimate and an engineering baseline.

AGL means above ground level. Enter the physical antenna height above the ground at each station; do not add the site's ASL height yourself.

12. ITU-R P.676 24/47 GHz gaseous loss

For every selected path, TropoScout v1.0.19 samples the forecast frame's GFS 2 m temperature, relative humidity and surface pressure along the same great-circle route and applies the ITU-R P.676-13 line-by-line gaseous-attenuation method.

The Engineering panel reports separate O2 (dry-air/oxygen), H2O (water-vapour) and Total loss at 24.048 GHz and 47.088 GHz, together with mean sampled temperature/RH/pressure and the percentage of the route covered by usable weather samples.

This is a forecast-dependent surface-path engineering estimate. It is not blended into PROPAGATION or SCATTER (EXP). v1.0.19 does not include rain attenuation or cloud liquid-water attenuation in this figure; those are separate higher-frequency mechanisms for later development.

13. ITU-R P.2001 reference

Where the optional P.2001 package is installed and applicable, TropoScout shows long-term/climatological basic transmission-loss reference values separately from the live GFS forecast.

Do not interpret P.2001 as today's duct forecast. It is a separate path reference and is intentionally not blended into the live propagation score.

14. Mobile operation

On a phone/tablet the interface changes to a compact operator layout. The map remains prominent and the information area is split into tabs such as Summary, Bands, Detail, Path and Engineering.

The SETTINGS button exposes less frequently changed antenna/playback controls so they do not consume permanent screen space.

15. How to interpret TropoScout

TropoScout is an opportunity forecast, not a guarantee that a contact will be possible. It is most useful when the live atmospheric forecast, path geometry and your own operating experience are considered together.

• PROPAGATION: GFS → refractivity N → modified refractivity M → gradient/trapping diagnosis.
• SCATTER (EXP): GFS → inversion/refractive contrast + shear/mixing proxies → experimental turbulent-boundary opportunity.
• Static engineering: terrain, effective-Earth and Fresnel geometry plus simple loss diagnostics.
• Forecast microwave gas loss: ITU-R P.676-13 O2/H2O attenuation at 24.048 and 47.088 GHz from sampled GFS surface weather.
• Climatological reference: ITU-R P.2001 where available.

GFS 0.25° pressure-level data cannot resolve every shallow boundary-layer or evaporation duct, particularly very local/coastal features. Real-world signals can therefore outperform or underperform the model.

16. Troubleshooting

No coloured forecast appears

Set a valid TX QRA and allow the regional forecast to prepare. A new QRA/radius may need to download its first GFS frame.

PLAY shows BUFFERING

The next forecast frame is still being prepared or loaded. TropoScout keeps the previous complete raster visible. In v1.1.2 browser preloads have a timeout/retry path; SCATTER warms only the immediate next frame while PROPAGATION can warm up to three.

No beacon/ATV markers

Check that the layer is enabled, the correct band is selected, and that stations exist within your TX radius for the active databases.

Terrain says pending

Terrain/P.2001 is calculated only after an RX path has been selected and may require terrain tiles to be fetched/cached on first use.

Changes after an upgrade are not visible

Force-refresh the main TropoScout page with Ctrl+F5 so the new JavaScript/CSS is loaded.

Playback performance

While PLAY is running, TropoScout animates the propagation overlay only. Path duct diagnostics and the RX M-profile refresh when playback is paused/stops, when NOW is pressed, or when a forecast frame/RX is selected manually. This prevents long animations from overloading the forecast service. First-use regional frames are pipelined server-side. Browser image decoding no longer gates SCATTER playback; an image that has loaded can be displayed immediately while decode remains best-effort.