Chris Collins

Tools · radio

Propagation and logbook

The greyline on a world map now or at any time, solar flux and Kp from NOAA, a simple MUF and band-opening estimate for a path, beam heading and distance, an ADIF logbook with dupe checks, statistics, a contact map and POTA/SOTA activations, and APRS — decoded from packets, KISS or a live APRS-IS feed — on a map.

Added

How to use it

Four tabs share You and DX (a Maidenhead locator, lat, lon, or — for the DX — a callsign, placed at its country’s reference point from AD1C’s cty.dat) and a UTC time (empty = now; the map and figures follow the clock).

Greyline shades the night side of a world map, with civil (−6°), nautical (−12°) and astronomical (−18°) twilight, the yellow terminator line and the point where the sun is overhead. It gives the sun’s elevation at both stations, the beam heading and distance (short and long path), sunrise and sunset for both in the next 24 hours, and the windows when both are in twilight — the greyline openings on 160–40 m.

Bands & solar shows the 10.7 cm solar flux (SFI), the planetary Kp and a 24-hour Ap, fetched from NOAA’s Space Weather Prediction Center (you can type your own), and estimates the maximum usable frequency (MUF), the optimum working frequency (FOT, 0.85 × MUF) and a rough lowest usable frequency for the path, now and over the next 24 hours, with each HF band marked open, marginal or closed. This is a simple, labelled model (below), for a feel of when bands open — not a forecast.

Logbook keeps an ADIF log in this browser. Type a callsign and the country, zones and continent appear; a ⚠ warns about duplicates (same call on the same band and mode — or by band, or the POTA rule of band, mode, UTC day and park), a frequency outside the band, or a malformed locator or reference. Click a row to edit it. Import ADIF / JSON reads .adi/.adx files from any logger (and adds countries where missing); Export ADIF writes ADIF 3.1.4. Statistics count QSOs by band, mode, country and continent; Activations groups your QSOs by your POTA park or SOTA summit and UTC day and marks valid activations (10 QSOs for POTA, 4 for SOTA); a map shows where your contacts are. The log never leaves the browser (IndexedDB) and is never in a share link — export it to keep it.

APRS decodes packets pasted as text (N0CALL-9>APRS,WIDE2-1:!4903.50N/07201.75W>…), a hex dump or file of KISS frames from a TNC, or a live APRS-IS feed around you, and puts the stations, objects and weather reports on a map with their tracks. Positions (uncompressed, compressed, Mic-E), objects, items, messages, status and weather are decoded per the APRS 1.0.1 specification.

Live APRS-IS goes through the gitwebsite app’s companion (receive-only, passcode −1; nothing is transmitted). The app connects only to TCP targets on its allow-list, and public servers are not offered automatically: add the server once with gw companion tcp add rotate.aprs2.net:14580 (or in the app’s Companion settings), then Connect. The feed is filtered to a radius around your locator (r/lat/lon/km).

Full screen (⛶ Full screen or F; Esc leaves) gives the tab’s map the whole screen.

The MUF model

foF2 (the F2 layer’s critical frequency) rises from a night floor of 2.5 + 0.012 × SFI MHz to a noon value of 5 + 0.042 × SFI MHz with the sun’s height at the path’s control point (the midpoint; on paths over 4000 km, the points 2000 km from each end, the lower deciding), and drops at high latitude in geomagnetic storms (Kp ≥ 5). The MUF is foF2 times the secant-law factor for the hop (hops of up to 4000 km off a layer 300 km up on a curved Earth — 3.3 for a 3000 km hop, the familiar M(3000)F2). The LUF is a rule of thumb for daytime D-layer absorption. The model ignores season, latitude detail, sporadic E, antennas, power and noise; use VOACAP or ITU-R P.533 for planning.

Limits

  • The sun’s position is NOAA’s algorithm (from the light planner), within about 0.01° of the Astronomical Almanac; the terminator is geometric (no refraction).

  • cty.dat gives countries and zones by prefix, not the ADIF DXCC entity numbers; QSL status, LoTW and eQSL are not handled.

  • APRS: telemetry and some rare formats are shown raw; transmitting (and a passcode) is out of scope.

  • NOAA’s feeds, wspr.live and OpenStreetMap tiles need the network; the logbook and decoders do not.

Related: ham radio (band plans, callsigns, locators), digital modes (decode FT8, PSK31, RTTY, CW, SSTV; WSPR spot maps), SDR receiver (hear the bands, APRS on 144.390 / 144.800 MHz), antennas, satellite passes, sun and moon.

Sources

  • Sun: NOAA Global Monitoring Laboratory solar calculator (after Meeus, Astronomical Algorithms). Checked against the USNO equinox and solstice times and the equation of time.

  • Solar indices: NOAA Space Weather Prediction Center JSON products (10.7 cm flux from Penticton; planetary K index), fetched directly.

  • ADIF: ADIF 3.1.4 specification. POTA activation: 10 QSOs (parksontheair.com rules); SOTA: 4 QSOs (SOTA General Rules).

  • APRS: APRS Protocol Reference 1.0.1 (Bob Bruninga WB4APR, 2000) and the APRS-IS server documentation (aprs-is.net).

Linking to an example

Share link copies the tab and settings (never your log). Parameters:

Parameter Meaning

me, dx

your locator or lat,lon; the DX locator, lat,lon or callsign

t

UTC time YYYY-MM-DDTHH:MM (empty = now)

sfi, kp

solar flux and Kp to use instead of NOAA’s

rule

dupes: band-mode, band or pota

aprs, is, km, call

APRS input (paste or live), APRS-IS server, radius (km), login call

Examples: the greyline from New England to Japan at the December solstice, London to Sydney at SFI 180, APRS.

Runs entirely in your browser — network requests go only to the services named on this page.