Deocoding Orbcomm with MultiPSK 4.31 and an RTL-SDR

MultiPSK is a signals decoding program with many available decoders to choose from. It is also able to directly connect to the RTL-SDR, or be used via a virtual audio cable. The latest beta version (available on the MultiPSK Yahoo mailing list) now allows for decoding of Orbcomm satellites which transmit at around 137 MHz. While it is not possible to decode the encrypted messages, it is still possible to decode pieces of telemetry data from the satellites. MultiPSK writes the following information about Orbcomm:

This system has been developed by the ORBCOMM society which disposes of a constellation of about 28 active LEO (“Low Earth Orbit”) satellites, transmitting between 137.2 and 137.8 MHz (+/- 2.5 KHz maximum of Doppler shift).

This system permits:

  • to handle messages (encrypted) from ground users
    (ships, trucks, oil wells…) until other ground users, through the ORBCOMM satellites, the cover being worldwide. These frames are decoded by Multipsk but not deciphered.
  • to broadcast identification, frequencies, position and orbital elements pieces of information, not encrypted. These frames are decoded and interpreted by Multipsk.

This mode is available for licencied copies, only (otherwise, the decoding is stopped after 5 minutes).

One user of MultiPSK has uploaded a video showing the Orbcomm decoding in action.

Multipsk 4.31 decoding Orbcomm

9 comments

  1. RON

    I’m going nuts here. Can’t seem to get MultiPSK to hear AIRSPY? I hear it through the laptop speakers and the headphones. SDRSharp see the AIRSPY but MultiPSK does not. Anyone have any ideas of what the heck I’m doing wrong? I’m thinking it’s an issue with the USB because I can connect my HF using the mic and headphone port and it works fine. Anything would help at this point. Thanks in advance.

  2. Jerome

    instead of adding yet more modes that wont work properly anyways, the author should revise the UI and what’s already there (and not working well either), e.g. that horribly broken RTL dongle support!

  3. Bob

    Well, geez, then why post the video at all if you don’t provide the link? That makes no sense. Wasted 20 minutes of my life looking for the button.

  4. Fouine91

    I, thanks for this info, but where did you find the 4.31 version ?
    On Patrick’s website the last version is 4.30 and i don’y have the Orbcomm button in professionnal modes. Moreover, i can see that in your video, your version number is also 4.30.
    Thank you.

    • admin

      The beta link is available on a message in the multipsk Yahoo group. I did not post the link because the author may not want new users downloading the beta.

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