AIS DSC MOB - confused

[jonathanhsm]

I'll ask the manufacturer and report back. In my reading I understood there were 'closed loop' systems where only the nominated MMSI (ie my boat is alerted) and 'open loop' where everyone is pinged. Surely the latter must be the case because as I said if I press the DSC button on the fixed VHF on my boat there's no point in it just alerting myself ?

 

[jakew009]

I'll ask the manufacturer and report back. In my reading I understood there were 'closed loop' systems where only the nominated MMSI (ie my boat is alerted) and 'open loop' where everyone is pinged. Surely the latter must be the case because as I said if I press the DSC button on the fixed VHF on my boat there's no point in it just alerting myself ?

Looking at the manual for the MOB2 device, it seems that the Class M devices can in fact now make DSC all ships calls, so I guess the SMRT one is going to do the same.

The MOB2 only has a 1 watt radio so it's not going to go very far anyway...

 

[Laser310]

i read something about the new class m devices, but didn't get what the fuss was about...

what are the significant differences between one of the new class m devices and the old devices?

 

[jonathanhsm]

In my limited understanding Class M devices limit AIS transmissions to channels 1 and 2 .... releasing the other 'cluttered' AIS channels for other emergency uses. And old devices which transmit on these frequencies will eventually be phased out.

 

[st599]

In my limited understanding Class M devices limit AIS transmissions to channels 1 and 2 .... releasing the other 'cluttered' AIS channels for other emergency uses. And old devices which transmit on these frequencies will eventually be phased out.

AIS only has 2 frequencies. There's a new system VDES which is rolling out across the EU (but not the UK) which has more digital channels.

 

[jonathanhsm]

AIS only has 2 frequencies. There's a new system VDES which is rolling out across the EU (but not the UK) which has more digital channels.

Thanks for the correction - have to admit it's all Greek to me - the blurb on Smrt website equally opaque.

This regulation (Class M) aims to prevent the Automatic Identification System (AIS) from being overwhelmed by off-ship devices like fishing net markers. From January 1, 2025, only Class-M DSC (Digital Selective Calling) MOB devices and Mobile AtoN will be allowed to use AIS Channels 1 & 2.

The regulation affects all devices not part of or fitted to a vessel, known as AMRD (Autonomous Maritime Radio Devices). Once adopted by each EU country, AMRDs that do not use DSC or have a DSC receiver, such as AIS-only MOBs, must either be taken out of use or moved to channel 2006, which requires a bespoke receiver.

This decision applies to all CEPT member countries, with each national authority deciding whether to adopt or reject it. In countries adopting ECC/DEC/(22)02, non-compliant MOBs will be illegal to use or license.