Record first
Both formats reward keeping the raw receive. A WAV or IQ file is the difference between a single attempt and a replayable experiment.
Mode comparison
SSDV versus analog SSTV: what changes at the receiver.
The names are close enough to invite confusion. Analog SSTV sends a picture as timed audio tones. SSDV sends packetised JPEG fragments, usually through a separate digital modem or frame layer.
Operational comparison
| Question | Analog SSTV | SSDV |
|---|---|---|
| What is on the channel? | Continuous audio tones that directly encode line timing, luminance, and colour components. | Digital packets carrying JPEG scan data and metadata. |
| How is the mode identified? | VIS or family-specific sync timing, with some historical modes requiring manual selection. | Packet type, callsign, image ID, packet ID, dimensions, flags, CRC, and optional FEC. |
| What should be recorded? | Audio WAV, decoded frame, mode, slant correction, frequency, and receive notes. | Raw audio or IQ, demodulated packet file, valid and failed packet counts, FEC corrections, and reconstructed JPEG. |
| How does failure look? | Slant, tearing, colour order problems, noise lines, sync loss, or wrong mode selection. | CRC failures, uncorrectable packets, missing packet IDs, incomplete MCU blocks, or a JPEG with visible gaps. |
| What improves the next receive? | Cleaner audio level, better timing correction, stronger path, and correct mode family choice. | Better modem lock, byte alignment, packet boundary recovery, FEC success, and combining packets from multiple listeners. |
Shared receiving habits
Trust public source notes
Satellite and balloon teams often publish frequency, timing, and format hints. Check the source before guessing from a partial receive.
Keep an evidence trail
A pretty image without frequency, UTC time, mode, transport, and decoder settings is less useful than a noisy image with a good log.
Why keep SSDV on SSTV.org.uk?
SSTV.org.uk is centred on pictures carried by radio. Analog SSTV remains the main reference library, but SSDV belongs in the same community notebook because UK high-altitude ballooning and amateur-satellite experiments have made digital image packets part of the wider receive practice. The site keeps the boundary explicit: SSDV is related image work, not an analog SSTV mode row.