*******************************************
*                                         *
*             SimpleSSTV                  *
*     SSTV Encoder/Decoder/Transmitter    *
*        for macOS and iOS                *
*                                         *
*******************************************


ENCODING (Image -> Audio)
=========================

  1. Load an image via drag-and-drop
     (macOS), photo library (iOS),
     or capture with camera
  2. Image auto-resizes to 320x256
  3. Select mode (Martin M1 is a
     good default)
  4. "Encode & Play" to transmit via
     speakers (for VOX-triggered
     radio), or "Save" as WAV/M4A
  5. Enable FSK ID to transmit your
     callsign (MMSSTV compatible)


DECODING (Audio -> Image)
=========================

  1. "Start Listening" for live mic
     input, or load a file
     (WAV, M4A, MP3)
  2. On macOS: System Audio capture
     for webSDR/SDR software
     (requires Screen Recording)
  3. Mode auto-detected from VIS code
  4. Image appears line-by-line with
     waterfall spectrogram
  5. FSK ID callsign detected and
     displayed if present


AUDIO TRIMMING
===============

  Precision editor for captured audio:

  - Dual-view: overview + zoomed strip
  - Drag handles for fine positioning
  - VIS auto-detection marks the SSTV
    signal start on the waveform
  - Spectrogram overlay shows signal
    frequency content


LIVE MODE (Camera -> SSTV)
==========================

  Automates capture-and-transmit:

  - Continuous: back-to-back TX
  - Motion:     TX on movement
                (adjustable sensitivity)
  - Periodic:   TX every 1-60 min
                (field day / unattended)

  iOS: switch front/back camera.
  Device stays awake during Live Mode.


RE-DECODE & HISTORY
===================

  Decoded images auto-save to history.
  From there you can:

  - Browse with timestamps
  - Re-decode: override mode, adjust
    sync position, correct slant
  - Preview before saving
  - Right-click / long-press to export


SUPPORTED MODES
===============

  Mode          Time   Notes
  ----------    -----  ----------------
  Martin M1     114s   Popular in Europe
  Martin M2      58s   Popular in Europe
  Scottie S1    110s   Popular in N. America
  Scottie S2     71s   Popular in N. America
  Scottie DX    269s   High resolution
  Robot 36       36s   Fast, YCbCr color
  Robot 72       72s   YCbCr color
  PD50           50s   Compact PD mode
  PD90           90s   PD mode
  PD120         126s   ISS favorite
  PD160         161s   PD mode
  PD180         187s   ISS favorite
  PD240         248s   High resolution PD
  PD290         289s   Highest resolution PD


FAQ
===

  Q: Why is my decoded image slanted?
  A: Sample rate mismatch or TX clock
     drift. App resamples to 44100 Hz
     automatically, but if still
     slanted, use Re-decode from
     history for manual correction.

  Q: App isn't detecting my signal?
  A: VIS code must be present at the
     start. If recording starts mid-TX
     or VIS is noisy, use Force Decode
     and select mode manually. Check
     waterfall for visible signal.

  Q: What audio formats for decode?
  A: WAV, M4A (AAC), and MP3.
     Different sample rates handled
     automatically.

  Q: What formats for export?
  A: WAV (uncompressed) and M4A.
     WAV for quality, M4A for sharing.

  Q: What is FSK ID?
  A: Transmits your callsign as
     digital data after the image.
     Compatible with MMSSTV.

  Q: Works with my radio?
  A: Yes, if you can route audio.
     - USB audio interface
     - Cable from headphone to mic
       (with level attenuation)
     - Acoustic coupling (hold mic
       near speaker, works in a pinch)
     Set radio to VOX for auto TX.

  Q: How does motion detection work?
  A: Adaptive background model that
     handles lighting changes and
     camera bumps. Sensitivity 1-50%.

  Q: What is the watermark?
  A: Free version adds small text.
     Remove it or set custom text
     (e.g. your callsign) with a
     one-time in-app purchase.

  Q: Can I receive ISS SSTV?
  A: Yes! ISS transmits on 145.800
     MHz FM during SSTV events,
     typically PD120 or PD180 mode.
     SimpleSSTV supports both.


LANGUAGES
=========

  Available in 10 languages:

  Arabic, Chinese (Simplified),
  Dutch, English, French, German,
  Polish, Portuguese (BR), Spanish,
  Turkish

  Full right-to-left support
  for Arabic.


ACCESSIBILITY
=============

  - VoiceOver: full support
  - Image descriptions via Apple
    Intelligence (on-device)
  - Clear status indicators and
    audio feedback


REQUIREMENTS
============

  macOS  15.0 (Sequoia) or later
  iOS    18.0 or later

  Mic access for live decode.
  Camera access for Live Mode.
  No internet needed - fully offline.


PRIVACY
=======

  No data collected or transmitted.
  No accounts, analytics, cloud sync,
  or third-party SDKs. Everything
  stays on your device.

  Full Privacy Policy


CONTACT
=======

  Email: jeroen@strangeloop.nl

  73 de Strange Loop Software


*******************************************