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.

Ships are labelled on the map with their names once they have sent them.

The two text services a ship’s radio keeps watch on: NAVTEX navigational and weather warnings on 518, 490 and 4209.5 kHz, and GMDSS Digital Selective Calling on VHF channel 70 and the HF distress frequencies. Messages print on a teleprinter, and a call that carries a position puts the vessel on the map. It is checked against the ITU tables and the IMO manual’s own worked examples; no real NAVTEX or DSC transmission has been decoded yet.

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

A station that moves, such as a balloon, draws a trail on the map with the altitude it reports.

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.

Meteor-M weather-satellite pictures on 137 MHz, from raw I/Q. Everything from the radio down to the data packets is written from published CCSDS documents and tested against them, but the last step, turning image packets into pixels, is a reconstruction. On a real pass it should lock and report what it hears, then refuse each image packet out loud rather than draw a wrong picture.

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.

Follows Vaisala RS41 weather-balloon sondes on 400 to 406 MHz: serial number, position, height, climb rate and wind, with each balloon’s trail on the map, up to four at once. It finds the sondes’ carriers itself, because nobody publishes them. It has never seen a real flight, and two details of the frame format are unconfirmed, so it may report nothing until it is checked against a real RS41. Asked for through the app’s feature box.

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. Optional PSK Reporter reporting under your own callsign — off until you enter one and switch it on — needs FoxSDR 0.99.43 or later for its settings boxes. 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 signalling of DMR digital radio, from NFM audio: colour code, group or private call, talkgroup, radio IDs, and the emergency and encryption flags. No voice is decoded and nothing is decrypted: DMR’s voice codec is patent-encumbered and is not in the plugin. Tested against a transmitter built from the standard, not yet against a real burst off the air.

What a TETRA cell broadcasts about itself, from raw I/Q: its network and colour codes, system information, slot assignments and channel grants, with whether each is encrypted. It plays no audio: no TETRA speech codec is present and nothing is decrypted, so a voice channel is labelled and left alone. Verified against a synthetic transmitter built from the ETSI standard, not yet against a real cell.

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.

Digital radio from Band III: it lists every station on a DAB or DAB+ multiplex and plays the one you pick, with its scrolling text and slideshow. Off the air in West Yorkshire it played stations from BBC National DAB and Digital One, DAB+ included. The slideshow and the title-and-artist tags have not yet been seen on a real signal, which is why it is still marked experimental. It needs exactly 2.048 MS/s, which an RTL-SDR offers. DAB+ sound needs ffmpeg, which you install yourself: the plugin contains no AAC decoder.

HD Radio, the digital signal beside many US FM stations: HD1 to HD8 audio, station and track information, album art, and traffic and weather maps. The plugin contains no decoder: it loads the libnrsc5 library you already have from NRSC5 Studio, a separate GPL program, and says so on its panel when it cannot find one. It has decoded nrsc5’s recorded sample, but never a live station inside FoxSDR.

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.

Works out what a digitally modulated signal is, BPSK, QPSK, 8PSK or 16-QAM, and measures it: symbol rate, carrier, EVM, MER, SNR and I/Q imbalance, with the constellation, eye and spectrum in one picture. It reads the live receiver channel or a recording in the common I/Q file formats, and can export the recovered bits. Tested against synthetic signals only, never a real off-air capture.

HF propagation in one picture: a world map with the grey line and a heat map of the bands likely to be open from your locator, solar indices, the NCDXF beacon schedule with tune presets, and a meteor-shower calendar. Predictions come from VOACAP, built in, which matches ITS’s own program on its test circuits but has never been compared with the air. It fetches solar data from N0NBH and NOAA while its window is open, and never sends your locator.

The Sun, planets and Moon drawn from orbital elements and turned with the keys on its plate, with NASA’s latest Sun pictures, the SOHO coronagraph, NASA’s list of coronal mass ejections, solar-wind readings and NOAA’s aurora forecast beside them. It contacts NASA and NOAA servers only for what is on screen. Tested against recorded responses, not yet inside FoxSDR’s own window.

A software TNC: 1200 baud AX.25 packet radio for Winlink Express, APRS clients and other packet programs, over KISS on a local TCP port. It can transmit, but only after you have granted it transmit and armed the transmitter yourself. Tested against a simulated host and a scripted client; not yet tried on the air. Not affiliated with ARSFI or Winlink.

Winlink-compatible e-mail through the internet gateway: a mailbox, a compose form and the B2F protocol. It makes no radio transmission yet, and needs an existing Winlink account. It passes tests against a fake gateway and another author’s implementation, but has never talked to the real Winlink servers. Not affiliated with ARSFI or the Winlink team.

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.

HFDL, the HF half of airliners’ ACARS, from USB audio: ground-station squitters, log-ons, messages and positions, printed on a cockpit message printer. About sixty of its air-interface values are reconstructions, because the standards that state them are paid documents, so it will most likely decode nothing off air until a real recording corrects it. It still reports each burst’s pre-key tone and carrier, so you learn whether it heard one.

The digital data link airliners use in the VHF airband, between 136.1 and 136.975 MHz: ACARS messages and ground-station announcements, up to twelve channels at once from raw I/Q, printed on a flight-deck message printer, with the positions stations announce put on the map. It has never decoded a signal from an aeroplane, and fifteen details of the signal could not be confirmed from any document, so it is published to be corrected against a real recording, not relied on.

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 868 MHz bursts European heat, water, gas and electricity meters send for walk-by reading, in Wireless M-Bus modes S, T and C, shown on a meter register with a roster of every meter heard. Most meters encrypt their readings, and it decrypts only those whose keys you enter, for meters you own or may read. It decodes the standard’s own example telegrams exactly, but has not yet heard a real meter.

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.