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
• 14 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
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
• 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
Note: It's super important to get a clean audio signal into the decoder. There's a new help section in settings with audio setup advice, USB adapter recommendations, and decode troubleshooting.
LIVE CAMERA MODE
• Real-time camera feed with front/back camera switching
• Three trigger modes: Continuous, Motion-triggered, or Periodic interval
SUPPORTED MODES (14 total)
• Martin M1 (114s), Martin M2 (58s)
• Scottie S1 (110s), Scottie S2 (71s), Scottie DX (269s)
• Robot 36 (36s), Robot 72 (72s
• PD50, PD90, PD120, PD160, PD180, PD240, PD290
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 14 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. Buy once, use forever. We do not use, sell or share your data for advertising or marketing purposes.
Be aware: Encoded images are audio signals, meaning anyone receiving the audio can decode them!
REQUIREMENTS
• iOS 18 or later
• Camera access for live mode
• Microphone access for live decode
This simple, no nonsense utility was built by a ham radio operator for ham radio operators. 73!
非常感谢您的支持，对我意义重大！希望中文本地化对您有帮助，虽然目前是 AI 翻译的。如有任何问题或功能建议，欢迎随时联系我。73！
Very nice THS
爱得门
After the update, some problems have been fixed, and the effect is very good. Thanks to the author's contribution spirit!
开发者回复
Thanks for the kind words. Whenever you have any issues, or ideas for future feature development, don't hesitate to reach out via the support page!
Good
WangHanbo_9191
It's okay when the receiving function seems to be unavailable.
开发者回复
Thanks a lot for trying out the app, and thank you for taking the time to write a review. They help me figure out what works and what doesn't for other people! The 0.4 version had a bug in the audio interface for phone versions other than the devices I had for testing. Upgrading to the new version, especially 0.7, should help increase decode quality and alleviate crashes.Good luck decoding images :)
