SDR software,
written from scratch.

Decodes a whole band at once from one radio. Four sets of channels sit close enough together that your receiver is already sampling all of them — six ACARS frequencies, seven NOAA weather channels, four paging channels, two APRS ones — but until now you could only decode one at a time, because those decoders work on demodulated audio and a receiver demodulates one channel at a time. This takes the raw stream instead, splits every channel out of it and runs a separate decoder on each, merging everything into one window with the frequency it arrived on at the start of the line. What it decodes follows where you tune it: point the radio at the weather band and you get all seven NOAA channels, at 931 MHz four pagers, at 144 MHz both APRS frequencies. There is a preset for each, and the panel lists every channel of whichever band you are on — whether your radio can reach it, the signal on it, and how many messages it has carried. The demodulators are the same ones those plugins use, unchanged.

Aircraft position, callsign and velocity at 1090 MHz. Decoded live off the air, with ICAO address blocks and callsigns agreeing across independent message types. The receiver's own DC offset is removed before detection, so a zero-IF dongle hears aircraft it used to bury. Version 1.7 hears considerably further: the test that decides whether a burst is a transmission at all was asking for about twice the signal-to-noise other decoders ask for, and the threshold that replaced it was chosen from seven minutes of real traffic rather than from argument — the same five minutes of sky went from 27 aircraft to 40, and from 20 of them carrying a position to 33. Version 1.8 reports what KIND each aircraft is — light aeroplane, airliner, heavy, helicopter, glider, microlight, unmanned — from the category every aircraft broadcasts beside its callsign, and FoxSDR draws each with its own icon — since 0.99.26 a shaded top view at 48 px (sized in VIEW > Display), with helicopters and a plain arrowhead for an aircraft that states no type. Measured over six minutes of real sky, 32 of the 33 aircraft that identified themselves stated one.

Turns a 24-bit aircraft address into who it actually is: registration, type and operator, shown on the map and in the track list. Since 1.1.0 it asks foxsdr.com's own aircraft database first — built from the OpenSky Network's aircraft data, and keeping no record of who asked about what — and only asks the volunteer-run adsbdb.com about aircraft we do not know.

Ship positions and voyage data on the marine band. Both channels at once from one receiver, plotted with everything else on the map.

Bell 202 packet radio from 144.800 MHz NFM audio: positions, messages, status and telemetry, validated against the AX.25 frame check.

Slow-scan pictures on HF and 2 m. The mode is read from the transmission's own VIS header, and clock drift is measured from the sync pulses, corrected, and reported in ppm.

The picture the NOAA satellites broadcast continuously on 137 MHz, built line by line as one crosses the sky. Both channels arrive side by side as sent — usually visible light beside infrared. Fitted alongside Satellites, that plugin says when NOAA 19 is next overhead and this one draws what it sends.

The direct broadcast from the GOES weather satellites at 1.7 GHz, from raw I/Q to the files it carries: full-disk pictures of the Earth, Rice-compressed imagery decompressed, and the EMWIN text products. It needs a dish of roughly a metre and a low-noise amplifier. Proven on NOAA's own published sample files; nothing taken straight off a satellite has been through it yet.

Reads the station on the 700 Hz note within 60 Hz either way, works the speed out from the signal and again after each pause, reads Farnsworth spacing and hand keys, and has an SAQ Grimeton preset.

45.45 baud amateur radioteletype on HF. Polarity is worked out from the signal rather than asked for, and both character sets are handled.

The WSJT-X weak-signal amateur mode, decoded slot by slot on the UTC clock and printed in WSJT-X's own layout — time, SNR, DT, audio frequency, message. Presets are WSJT-X's FT8 dial frequencies from 160 m to 2 m. Asked for through the app's feature box. Built on ft8_lib (MIT) and KISS FFT (BSD-3-Clause).

The four-letter calls HF aeronautical stations send to alert one aircraft's crew, with all 32 ICAO tones and the standard's timing checked — a call that misses it is still reported, with the reason. Ten North Atlantic HF presets. Asked for through the app's feature box.

All three bit rates and inverted polarity detected automatically. The BCH error-correcting code is implemented in full: damaged codewords are discarded rather than shown as text.

The digital headers carried by every US Emergency Alert System message and NOAA Weather Radio alert, printed in words: the event, who issued it, which counties it covers and how long it is valid for. The header is sent three times and this votes on the copies, so an alert survives noise that damages each one differently.

The ISS, amateur birds and weather satellites drawn live on the map with their predicted ground track, a pass table for your own station, and Doppler correction that holds a moving downlink through a pass. Orbits come from CelesTrak element sets, so what it draws is computed rather than received.

Street-level tiles under the map, fetched from a tile server you run yourself, which is what keeps the imagery licensing with whoever serves it.

Point it at a band, leave it running on a machine that is on anyway, and come back to what was actually used: which frequencies, how wide, how strong they got and how often they were there. It reads the whole receiver bandwidth at once rather than one channel at a time.

Notices a transmitter far stronger than everything else in the band the radio is sampling - usually a handheld or a mobile close by - and, if you allow it, brings the receiver to it so you hear it. It works like the Close Call feature on Uniden scanners, and is not made or endorsed by Uniden.

Maritime safety broadcasts. Roughly ten of its air-interface constants are reconstructed guesses, so it will most likely decode nothing off air — and it is published saying exactly that, in its own name.

The reference plugin: reports the RMS level of the demodulated audio, and exists to show what writing one looks like.

This decodes POA — plain ACARS — and not VDL Mode 2. POA is the original character-oriented link: 2400 baud MSK on an AM carrier, seven ASCII bits and an odd parity bit per character, on 131.550 MHz over North America and 131.725 MHz over Europe. VDL Mode 2 is a different waveform on different channels — D8PSK at 31,500 bit/s, around 136 MHz, carrying AOA rather than characters — and nothing here demodulates it.

What arrives on POA is the messages airliners and ground stations exchange — position reports, clearances, engine and maintenance traffic — printed as they come in. The window is drawn as an airliner's cockpit printer, feeding paper.

FLEX pager traffic, held in a memory you can scroll back through rather than a log that scrolls away. The window is drawn as a 1990s pager, with a liquid-crystal display and a message memory.

The two-tone sequential pages that open a station's alerting: the tone pair identifies who is being called, and the receiver responds to it as the real equipment does. The window is drawn as a fire-station alert receiver.

The VHF omnidirectional range beacons aircraft navigate on. Turn the OBS and the needle answers, exactly as the instrument in the aeroplane does. The window is drawn as a cockpit course indicator, with a working OBS knob.

The weather charts broadcast to shipping, drawn as the fax machine that used to receive them would have drawn them, lamp ladder and all. The window is drawn as a marine fax machine's control panel.

The 406 MHz beacons carried by aircraft, vessels and people. The window is an alarm panel because that is what the signal means. The window is drawn as an alarm panel, the fifteen-character identity on seven-segment glass.

The short bursts domestic electricity, gas and water meters send for drive-by reading, shown on a register like the one on the meter itself. The window is drawn as an electricity meter's register.

The garden temperature and humidity sensors on 433 MHz, displayed on the kind of console they were sold with. The window is drawn as an Oregon Scientific console.