OnAirDecode SSDV pictures with an SDR
SSDV: balloon and satellite pictures, built up packet by packet.
- Group
- Weather & science
- In the mode list
- balloon / satellite pictures, 70 cm
What SSDV pictures is
SSDV (Slow Scan Digital Video) pictures from high-altitude balloons and amateur satellites: FM / FSK channel, 256-byte SSDV packets checked with their CRC-32 and the Reed-Solomon code, the JPEG rebuilt as packets arrive (grey where packets are missing), saved as JPEG when complete. Plain FSK 1200 - 19200 baud and RTTY-framed bytes 300 - 1200 baud are tried at the same time, both polarities.….
Frequencies and settings
OnAir takes any frequency you type; the numbers above are the mode's starting point and the range its table describes. In the app the shortcut label is balloon / satellite pictures, 70 cm.
What OnAir shows
SSDV (Slow Scan Digital Video) pictures from high-altitude balloons and amateur satellites: FM / FSK channel, 256-byte SSDV packets checked with their CRC-32 and the Reed-Solomon code, the JPEG rebuilt as packets arrive (grey where packets are missing), saved as JPEG when complete. Plain FSK 1200 - 19200 baud and RTTY-framed bytes 300 - 1200 baud are tried at the same time, both polarities. Scrambled / AX.25 / IL2P framing, Wenet (LDPC, 115 kbaud) and LoRa are not handled. SSDV code by Philip Heron (GPL-3.0-or-later).
Limits and what it was checked with
Checked with generated signals and impairments; recordings of real signals welcome.
Which radio you need
Any radio that tunes this range works. An RTL-SDR covers roughly 24 MHz to 1.7 GHz, and every other radio in the radio guide reaches it too. Antenna height and a clear view of the transmitter matter most.
Receiving and the law
Questions about SSDV pictures
Can I decode SSDV pictures with an RTL-SDR?
Usually yes for narrowband signals, as an RTL-SDR tunes roughly 24 MHz to 1.7 GHz at up to about 2.4 Msps. Wide signals such as TV channels need a faster radio, and OnAir says next to the source what the selected radio can do.
Is it legal to receive SSDV pictures?
Receiving these signals is legal in most countries. OnAir is a receiver.
Can I try SSDV pictures in OnAir without a radio?
Yes. Most modes include a built-in synthetic test signal, so you can open the screen and try the controls before you own a radio.