Class B & the FCC, sounds good

Ben Ellison

Ben Ellison

Panbo editor, publisher & chief bottlewasher from 4/2005 until 8/2018, and now excited to have Ben Stein as very able publisher, webmaster, and editing colleague. Panbo is going to the next level in 2019 and beyond.

5 Responses

  1. Roger says:

    Ben, Am I missing something here? AIS transmits the MMSI number to enable a DSC/VHF to contact that vessel if necessary. How can that work if another MMSI is used by AIS that does not correspond to the MMSI programmed into the DSC/VHF?

  2. del says:

    Roger:
    You are quite correct, the MMSI is allocated to the vessel and should be the same in both the DSC and the AIS. In the UK, MMSI’s are administered differently and are issued as part of the ships radio licence (free) and so would be the same anyway. I’m not quite sure how the US system works, but it would seem open to some confusion, perhaps?
    Maybe this is why the FCC insisted on the manufacturer code and serial number field as well as a cross check that the MMSI is correctly matched? … Maybe?

  3. Richard-I says:

    I can see one security concern. If the manufacturer does not program in the MMSI, it opens the way to user’s changing their AIS identity. Having the manufacturer’s number transmitted means that the blame comes back, so perhaps inhibiting the manufacturers’ desire to delegate programming.

  4. marinate says:

    The Class B IEC spec states that the user must not be able to alter the MMSI once programmed. Therefore even if users do have the ability to programme the MMSI they won’t be able to change it (like a DSC radio).

  5. bobetter says:

    I have a Comar CSB 200, one of the SRT boxes. Both the SW and the manual very specifically state that entering the MMSI is a one shot deal. The routine even has a “Are you sure?” module in it.

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