OnAirSatellite & navigation · Experimental
Decode Orbcomm with an SDR
OnAir receives Orbcomm. Orbcomm subscriber downlinks, 137.2 - 137.8 MHz: 4800 bit/s SDPSK, two downlinks at once, satellites and their ephemeris.
What Orbcomm is
Orbcomm is a satellite data network with downlinks near 137 MHz, used for tracking and telemetry of assets.
Frequencies and where it is used
Satellite data downlinks, 137.2 to 137.8 MHz (4800 bit/s SDPSK).
In OnAir the tuning shortcut is Satellites, 137 MHz; you can enter any frequency your radio reaches.
What OnAir shows for Orbcomm
Two downlinks at once with Doppler tracking, satellites on the map from their ephemeris, packet log by type.
This receiver is built from the published specification and checked end to end on simulated signals. It has had little or no testing on real transmissions yet, so reports and recordings on Discord are 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.
Questions about Orbcomm
Can I decode Orbcomm 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 Orbcomm?
Receiving satellite downlinks is generally legal. Encrypted or spread content is not decoded, and voice codecs that are patented are not shipped with OnAir.
Can I try Orbcomm 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.
Try it without a radio
OnAir includes built-in synthetic test signals for most modes, so you can open this screen, see the layout and try the controls before you own a radio. The Tour button walks you through the app.