Signal K•2w ago

I don't understand what you are meaning

I don't understand what you are meaning? AIS Msg 1 is for class A vessel position report. Check Msg IDs and contents e.g. from here https://www.navcen.uscg.gov/ais-messages If needed to continue about AIS topics, then let's continue that in separate thread.

8 Replies

Владимир Калачихин•2w ago

Come on, bro, I know. AIS Search and Rescue Transmitter (SART) | IEC 61097-14 Mobile equipment to assist homing to itself (i.e. life boats, life rafts). An AIS SART transmits a text broadcast (message 14) of either 'SART TEST' or 'ACTIVE SART'. When active the unit also transmits a position message (message 1 with a 'Navigation Status' = 14) in a burst of 8 messages once per minute. AIS SARTs are also used in maritime survivor locating devices (MSLD) or man overboard (MOB) devices, as specified in RTCM 11901.1, Standard for Maritime Survivor Locating Devices as well as for AIS locating beacons on 406 MHz EPIRBs. Standard AIS SARTs can be identified by MMSI's beginning with the numbers "970", AIS maritime survivor locating devices or MOBs with MMSIs beginning with "972", and AIS EPIRB with MMSIs beginning with "974". All categories of AIS SARTs will be displayed on IMO-mandated shipboard navigation displays. Read the docks, they are rules.

Karl-Erik GustafssonOP•2w ago

Safety Msg is nr 14. In addition to that SART sends Msg 1. Msg 1 is already decoded by SK and state 14 = ais-sart is included. https://github.com/SignalK/nmea0183-signalk/blob/master/hooks/VDM.js#L42 You see SART devices listed by SK, but Msg 14 is not included now and question is mainly how safety level alarm should be handled in SK. Am I missing something?

Владимир Калачихин•2w ago

Am I missing something?

No docs about msg 14 content is present. Apparently, the combination of the three parameters: (mmsi==(970XXXXXX or 972XXXXXX or 974XXXXXX) and Navigation Status= = 14 and msg14 with mmsi==(970XXXXXX or 972XXXXXX or 974XXXXXX)) indicates a SART device: the MOB buoy, EPIRB buoy or some mobile equipment in active mode (not a test mode). And this situation can be interpreted as a MOB. But three parameters at the same time are very difficult for the nauticals 🙂 Is it possible to send Navigation Status= = 14 for a vessel with its own mmsi? Or send msg 14 with the vessel's mmsi without other conditions? And it seems native to use Navigation Status= = 14 to indicate the incident on the vessel, with send msg 14 with details. But I have not found any documentation or practice cases on this theme. Therefore, I would like the SignalK to display the message 14 in some standard way so that users apps can use it as they see fit.

Karl-Erik GustafssonOP•2w ago

SART, MOB and EPIRB are using Msg 14 for info content + Msg 1 for location SART ACTIVE or SART TEST and similar for two others, no other references. Even IA is not capable to find any souces: "I could not locate a real-world Message 14 safety-related text example from a verified source in the searches I performed." 😆
I don't know about sending this type of message, more concerned about procedure when receiving msg 14...

Владимир Калачихин•2w ago

Even IA is not capable to find any souces:

Pragmatic note: On [AISHUB] the actual content of these messages is highly variable, ranging from fairly plain English ("PLEASE REPORT TO JOBOURG TRAFFIC CHANNEL 13") through snippets of tabular data ("PAX 589 FG 36 IX 74 MOTO 10 CREW 108+1" through what look like opaque commercial codes ("EP285 IX46 FG3 DK8 PL56") to empty strings and content that looks like line noise ("]XFD5D/\7`>PA!Q DX0??K?8?>D").

I don't know about sending this type of message, more concerned about procedure when receiving msg 14

  "urn:mrn:imo:mmsi:201246757": {
    "navigation": {
      "safety_related_text": {
        "meta": {},
        "value": "We have a medical emergency!",
        "$source": "netAIS-plugin.XX",
        "timestamp": "2025-01-23T20:53:31.000Z"
      },

  "urn:mrn:imo:mmsi:201246757": {
    "navigation": {
      "safety_related_text": {
        "meta": {},
        "value": "We have a medical emergency!",
        "$source": "netAIS-plugin.XX",
        "timestamp": "2025-01-23T20:53:31.000Z"
      },

Владимир Калачихин•2w ago

BTW, What it looks like in my interpretation. (Data from the simulator.)

Владимир Калачихин•2w ago

And how looks AIS target with msg 14 and Navigation Status= = 14. (left bottom mark, simulation too)

Karl-Erik GustafssonOP•7d ago

I expected to find something similar in real life, but reality was a bit different.

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I don't understand what you are meaning

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