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VHF Logger

User guide and setup — VHF/UHF contest logger with aircraft scatter

1. First-time setup

When you open the logger for the first time, Settings opens automatically. Fill in these fields:

2. Logging a QSO

Use the entry fields in the bottom-left panel:

1. Call — the other station's callsign. Autocomplete suggests matches from your locator database (see section 5).
2. Time — filled automatically with UTC. Correct if needed (format HHMM).
3. RST S / RST R — sent and received signal reports.
4. Nr S / Nr R — serial numbers (enable under Serial numbers in Settings).
5. Loc — the other station's Maidenhead locator. Distance is calculated automatically.

Press Enter to move to the next field. The QSO is saved automatically when the locator is entered.

One-liner mode

Enable under Entry mode → One-liner in Settings. Type everything on one line and press Enter.

Important convention: the RST you send (your report to the other station) is marked with an apostrophe ' after it. The RST you receive is written without an apostrophe.

Full format: CALL [SND-RST'] [RCV-RST] [NR] LOCATOR
Locator and callsign are the only required fields — everything else is optional and falls back to defaults (RST 59).

3. Score

The score is shown continuously in the bar below the top menu:

• KM pts — sum of distances for valid QSOs
• WWL × 500 — 500 points per unique Maidenhead square (4 characters)
• Total = KM pts × band multiplier + WWL bonus

4. EDI export

Click ↓ EDI to download your contest log in REG1TEST format (Tucnak-compatible). The file can be uploaded directly to vushf.dk.

Filename: CALL_144MHz_DATE.edi

5. Locator database

Import a text file with known stations for callsign autocomplete:

G3YDY;JO01FQ;Don
G4SWX;JO02RF

Format: CALL;LOCATOR or CALL;LOCATOR;NAME — one station per line.

Click 📂 Load locator file in Settings. The database is stored in the browser.

6. Aircraft scatter

Aircraft scatter allows VHF/UHF QSOs over long distances via reflection from aircraft. Flight data is fetched via vushf.dk as a proxy — it tries airscatter.dk first and automatically falls back to OpenSky Network if airscatter.dk is unavailable. The active source is shown in the info bar below the map: 42 aircraft · airscatter.dk or 42 aircraft · OpenSky.

Getting started with scatter

1. Click ✈ Planes in the top bar — aircraft within the search radius are now fetched every 10 seconds.
2. Open the Watchlist tab in the left panel.
3. Add stations you want to monitor (callsign + locator) under Settings → Watchlist.
4. Tick the stations you want to check scatter against.
5. The logger automatically shows which aircraft are in scatter position and when the next one arrives.

What does the watchlist show?

Scatter parameters

The scatter corridor angle and minimum aircraft distance are set automatically based on the selected band. You can adjust them manually in Settings:

Map overlays

• Zone — shows the yellow scatter corridor polygon on the map
• Lines — shows a green line between your station and the remote station during active scatter

7. ON4KST chat

The logger has a built-in client for the ON4KST VHF chat network. Use it to arrange skeds with other operators during a contest.

Connecting

1. Click the KST tab in the top-left panel.
2. Enter your callsign, password and the channel you want to join (e.g. 144 for the 144 MHz room).
3. Click Connect — incoming messages appear in the chat window.
4. Type a message in the input box at the bottom and press Enter to send.
5. Click Disconnect to log out.

Right-click — scatter sked from Watchlist

When a station in the Watchlist tab is also online on KST it shows a ·KST badge next to its callsign. Right-click the callsign to open a context menu with a pre-filled scatter sked message:

CALL pls sked on 144.300 AP in 8 min

The frequency is taken from your active band and the time is the current scatter ETA. Edit the message if needed and press Enter to send it.

Online tab — all logged-in users

The Online tab (tab 4) shows all stations currently logged into the KST channel. Click Fetch active users to refresh the list. The list is filtered by distance — only stations within the configured maximum (default 1000 km) are shown.

Right-click any callsign in the Online list to send a CQ message pre-filled as /cq CALL.

8. Layout

• Drag the vertical divider between the log panel and the map to adjust the width.
• Drag the horizontal divider above the watchlist to adjust the map height.
• Switch between Log list, Watchlist, KST and Online using the tabs in the top-left.
• Select a theme (dark / dim / warm / light) from the dropdown in the top-right.

9. Keyboard shortcuts

10. Data and backup

The log is saved automatically in the browser's localStorage after every QSO — it survives browser restarts. Data is not deleted when the page is refreshed.

To move your log to another computer: use the browser DevTools (F12 → Application → Local Storage) and copy the keys zlog_log and zlog_settings.