PhosphorSSTV decodes SSTV (Slow Scan Television) signals in real time using your iPhone's microphone. Hold your phone near a shortwave radio tuned to an SSTV signal and watch the image build scanline by scanline on an authentic phosphor CRT display.
No internet connection required. No external hardware. No account. Just your iPhone and a radio.
FEATURES
- Real-time SSTV decoding via microphone — 10 modes supported
- Scottie S1, S2, DX — the most popular SSTV modes on HF
- Martin M1, M2 — widely used in European SSTV activity
- Robot 36, 72 — YCbCr colour, used by the ISS during special events
- Robot 8, 12, 24 BW — fast greyscale modes
- VIS code detection with automatic mode confirmation
- Sync-aligned slant correction — zero drift, straight vertical edges
- Progressive scanline rendering — image builds top-to-bottom like a real SSTV monitor
- Live FFT spectrum display and scrolling waterfall
- Image log with thumbnails, metadata, and sharing
- Green and amber phosphor CRT themes with scanlines, vignette, and glow effects
- No accounts, no tracking, no network access
DSP ENGINE
Per-sample Hilbert transform FM discriminator (31-tap FIR, Blackman window) for instantaneous frequency estimation. Sync-aligned line detection seeks the 1200 Hz sync pulse at every line boundary, eliminating cumulative clock drift. 512-point FFT for spectrum analysis. All signal processing runs entirely on-device.
DECODER ACCURACY
PhosphorSSTV has been tested against synthetic test patterns and third-party encoded signals across all supported modes. Detailed test results, methodology, and decoded image samples are available in the decoder test report.
WHERE TO FIND SSTV
- 20m band: 14.230 MHz USB — primary worldwide SSTV calling frequency
- 80m band: 3.845 MHz LSB (3.730 in Europe)
- 40m band: 7.171 MHz LSB (7.165 in Europe)
- 15m band: 21.340 MHz USB
- 11m band: 27.700 MHz USB — international calling
- 10m band: 28.680 MHz USB
- ISS: 145.800 MHz FM — during special SSTV events (Robot 36/PD modes)
A shortwave receiver, SDR, or WebSDR audio played through a speaker is all you need.
SUPPORT
Need help? Have a question, bug report, or feature request?
- Ask a question — get help with using PhosphorSSTV
- Report a bug — let us know if something isn't working
- Request a feature — suggest improvements or new functionality
You can also browse existing issues to see if your question has already been answered.