Microphone receiving
Allow microphone access, set the radio volume so the spectrum is visible without clipping, keep the speaker close to the device, and start receive before the VIS header if automatic mode detection is desired.
Support
Support for SSTV receiving and transmitting.
Most receive issues come from audio routing, microphone permission, signal level, mode mismatch, or a transmission that ended before the frame completed.
File decoding
WAV is the safest input format. If a compressed recording fails, export or convert it to WAV, keep the original sample rate if possible, and start decode from the beginning of the SSTV transmission.
Lite unlock
Lite includes five successfully saved decodes. Use Restore purchases after reinstalling or moving to a device signed into the same Apple account that bought Permanent Decode Unlock.
Receive checklist
| Symptom | Likely cause | What to try |
|---|---|---|
| No image starts | VIS header missed, wrong mode, or low audio level | Record the whole pass, choose the mode manually, and confirm sync energy is near the 1200 Hz marker. |
| Image is slanted | Sound-card or device clock mismatch, Doppler drift, or tuning offset | Use slant correction, retune so the video band sits between 1500 and 2300 Hz, and keep the receiver stable during the frame. |
| Colors look wrong | Wrong mode family or partial decode | Compare VIS/mode notes. Martin and Scottie are RGB families; Robot, PD, and MMSSTV MP/MR/ML use color-difference coding. |
| Satellite image breaks up | Short pass, fading, Doppler, antenna polarization, or event gaps | Check the official event frequency and mode, begin recording before AOS, and expect multiple passes for a clean image. |
Permissions used by the apps
Microphone
Used only when you start live receive so the app can decode audio from a radio, speaker, or acoustic source.
Photos and Files
Used when you import an image or audio file, save decoded images, export WAV files, or keep RX/TX archive items.
Location
Used for satellite pass timing and direction calculations when the satellite tools need your observing location.
Mode support
The app-supported mode list is published in the docs and generated from the Swift mode table during the site build. If a mode is shown as reference-only or needs-verification, it is included for study and comparison, but it is not presented as a supported receive/transmit path.
Contact
For support, include the app edition, app version, iPhone or iPad model, iOS/iPadOS version, mode name, whether the source was microphone or file decode, and a short description of the signal source. Do not send private call logs or third-party recordings unless you have the right to share them.