SimpleSSTV vs PhosphorTEX

SimpleSSTV is a native iOS app for encoding, decoding, and live-transmitting slow-scan television (SSTV) signals — the method ham radio operators use to share images over audio frequencies. Slow-scan television converts images to audio tones. Each pixel's brightness becomes a specific frequency between 1500-2300 Hz. Sync pulses at 1200 Hz mark line boundaries. The result is an audio signal you can transmit over any voice-capable radio, or record for later playback. SSTV has been used by amateur radio operators since the 1950s. It's still actively used today on HF bands, VHF repeaters, and for receiving images from the International Space Station. ENCODING (Image → Audio) • Load any image from your photo library, camera, or Files • Automatic resize and crop to SSTV resolution • 21 supported modes covering all major SSTV formats • Real-time encoding with progress visualization • Play audio directly through speakers for VOX-triggered transmission • Export to WAV or M4A for later use • Optional FSK ID and CW ID (Morse code) callsign transmission • Test pattern generator for signal testing LIVE CAMERA MODE • Real-time camera feed with front/back camera switching • Three trigger modes: Continuous, Motion-triggered, or Periodic interval • Adjustable motion sensitivity with adaptive background model • Captures and encodes directly from camera to audio • Perfect for portable operation, field day, and unattended stations DECODING (Audio → Image) • Load WAV, M4A, or MP3 audio files containing SSTV signals • Live microphone capture for real-time SSTV reception • Automatic mode detection via VIS code identification • Progressive line-by-line image preview during decode • FSK callsign detection from received signals • Precision audio trimming with dual-view waveform editor • Re-decode saved images with different mode, sync offset, or slant correction • Handles real-world signal imperfections: timing drift, noise, sample rate variations • Optional decode watermark stamps mode, timestamp, and callsign on received images • Waterfall spectrogram display shows signal frequency over time SUPPORTED MODES (21 total) • Martin M1, M2, M3, M4 • Scottie S1, S2, S3, S4, DX, DX2 • Robot 36, Robot 72, Robot BW8 • PD50, PD90, PD120, PD160, PD180, PD240, PD290 • Wraase SC2-180 ISS SSTV EVENTS • Get notified when the International Space Station transmits SSTV images • Automatic alerts before and during events, with frequency, mode, and callsign info • Info card on the decode tab with event details and countdown FAQ & SETUP TIPS • Practical advice on audio setup and USB adapters • Decode quality troubleshooting • Quick reference for all 21 SSTV modes IMAGE LIBRARY • Automatic saving of encoded and decoded images • Grid view with full preview, metadata, and sharing • Re-decode any saved image with different settings • Filter by encoded or decoded 10 LANGUAGES Available in Arabic, Chinese (Simplified), Dutch, English, French, German, Polish, Portuguese (BR), Spanish, and Turkish — with full right-to-left support. PRIVACY No accounts, no analytics, no tracking. Your images and audio stay on your device. Free to encode and decode. Optional one-time Pro purchase unlocks watermark customization and Listening Station Mode. We do not use, sell or share your data for advertising or marketing purposes. Be aware: Encoded images are audio signals — anyone receiving the audio can decode them! REQUIREMENTS • iOS 17.6 or later • Camera access for live mode • Microphone access for live decode Built by a ham radio operator for ham radio operators. 73!

PhosphorTEX is a real-time NAVTEX maritime-safety decoder for iPhone. Tune a shortwave receiver to 518 kHz, 490 kHz, or 4209.5 kHz, hold your iPhone near the speaker, and watch navigational warnings, gale warnings, ice reports, and other maritime safety information scroll across an authentic amber phosphor CRT display. NAVTEX (Navigational Telex) is broadcast worldwide under the IMO Global Maritime Distress and Safety System (GMDSS). Every coast, mariners and ship's radio officers depend on it for up-to-the-minute storm warnings, search-and-rescue notices, navigational hazards, and coastal traffic advisories. PhosphorTEX brings that same live maritime feed to your iPhone — offline, on-device, no account, no network. SIGNAL PROCESSING PhosphorTEX implements the full CCIR-476 SITOR-B protocol stack in Swift with purpose-written DSP. • Synchronous 7-bit framer with DPLL clock recovery • Time-diversity FEC: alpha / rep pair-merge per CCIR-476 spec • Shift-until-valid phase search with sentinel-aligned alpha / rep routing — locks to the correct character boundary automatically • Polarity auto-detection — works with maritime-receiver tuning (mark ~1615 Hz) and SDR tuning (mark ~1085 Hz) equally, no toggles • Automatic frequency control with sub-bin parabolic peak interpolation and ±3 Hz/frame centre-tracking clamp • 170 Hz shift locked to spec (±85 Hz around centre) • Live 512-point FFT spectrum and scrolling waterfall display DECODE VIEWS • CARDS — parsed NAVTEX messages as colour-coded cards: station letter, subject badge (SAR/piracy, nav warning, met warning, ice report, met forecast…), serial number, timestamp, FEC quality badge, full body text • TAPE — raw teleprinter character stream, for purists NAVAREA SCHEDULE Built-in database of 42 NAVAREA coast stations across NAVAREA I through XVIII (Cullercoats, Niton, Rogaland, Oostende, Reykjavik, Mondolfo, Las Palmas, Horta, and more). The SCHEDULE tab shows a live 24-slot grid with the current 10-minute broadcast slot highlighted in real time against a ticking UTC clock. MESSAGE LOG Every decoded message is logged locally with timestamp, header, body, and FEC statistics. Swipe to delete. Tap for full view. Export the whole log as plain text via iOS share sheet. CONFIGURATION • Two phosphor themes: classic amber and green • Three font sizes for the decoded output • AFC on/off with manual mark frequency override for unusual receivers • Invert mark/space for LSB-convention receivers • Per-subject mute list (urgent D-category SAR/piracy messages always override) • Alert toggles for SAR/piracy and vital (serial-00) messages PRIVACY PhosphorTEX makes zero network requests. No account, no cloud, no analytics, no tracking, no third-party SDKs. Audio is processed entirely in memory — nothing is recorded, stored, or transmitted. Microphone access is used only for live signal decoding. WHAT YOU NEED An iPhone and a shortwave receiver tuned to NAVTEX — 518 kHz for international English, 490 kHz for national language broadcasts, or 4209.5 kHz for tropical HF. Most entry-level general-coverage receivers work. WebSDR audio played through a speaker works too. PhosphorTEX is part of the Phosphor suite of retro-CRT radio tools: PhosphorRTTY (RTTY), PhosphorCW (Morse), PhosphorFeld (Hellschreiber), PhosphorSSTV (slow-scan TV), and more. Look out for bundles as new apps become available. Built in Swift with Apple's native frameworks only. No external dependencies. Runs entirely on-device.