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, documentation, and apps.
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 1.x includes five successfully saved decodes. In 2.0, three SSTV or Weather Fax receives are included; one use is counted when a supported mode is identified, even if reception does not finish. The one-time Permanent Full Unlock enables unlimited receiving and the digital-image and advanced transmit tools. Use Restore purchases after reinstalling or moving to a device signed into the Apple account that bought the unlock.
2.0 protocol and input help
Use the protocol guide to identify the signal family and the receiver input reference to match the source format. SSDV link profiles, Weather Fax settings and DRM A-E data sheets each link to known sample material.
DRM Mode E requires 192 kHz complex I/Q. For Weather Fax, select LPM and IOC manually. A valid SSDV telemetry frame need not contain a complete image. Compare the recording with the lossless sample library before diagnosing the radio path.
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, iPad, or Mac model, OS version, mode name, whether the source was microphone, file replay, or an external radio, 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.