Send modes explained
Photo, Hybrid, Open Signal digital and analogue SSTV — what each send mode is for, what it costs in airtime, and which one to pick for the station you are working.
Open Signal sends pictures four ways. The mode chips on the Transmit screen pick one; the staged preview always shows the honest result and the true cost before anything keys.
Photo (recommended for quality)
The actual JPEG file travels over the air in error-corrected bursts and decodes pixel-perfect at the far end — like EasyPal. Choose the size (e.g. 480 px) to trade airtime against resolution. A missed burst is repaired by the fountain-code stream; deep fades just mean it takes a little longer.
Hybrid (fastest — needs internet both ends)
The full-quality picture uploads through the Open Signal picture service and only a short link goes over RF (~5 seconds of airtime). The receiver’s app fetches the original automatically. Full detail, GIFs stay animated, barely any airtime — see Hybrid mode.
Digital (Open Signal’s own colour mode)
The picture is wavelet-compressed and streamed as colour data. Progressive: the receiver sees it sharpen as bursts arrive. Good middle ground when the other side runs Open Signal and there’s no internet.
Analogue SSTV (works with everyone)
Classic Martin/Scottie/Robot/PD transmission — any SSTV program on any radio can receive it. Quality is what analogue SSTV is: noise shows as streaks. The transmit bar shows a live time left countdown while it plays out. See SSTV modes.
Which one?
| You want | Use |
|---|---|
| Best quality over RF only | Photo |
| Fastest, both ends online | Hybrid |
| Other side isn’t running Open Signal | SSTV |
| RF-only to another Open Signal station | Digital or Photo |
New to Open Signal?
Start with the overview — what it does, the honest status, and how the pieces fit together.