MEWS: Marine Electronics Wiki

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====== AIS / VDES ======

There is a possibility to transmit arbitrary data using AIS transponders. This could be used to send text messages and telemetry by sending the same messages as might be sent over LoRa. I think AIS also has its own weather report format(s) and text messaging.

AIS may allow for longer range between vessels, and use of extensive shore and satellite receiver networks.

This could be done, with AIS Addressed Binary Messages, or Broadcast Binary Messages. Messages types 6 and 8 may be suitable.

Some AIS transponders will accept NMEA0183 ABM and BBM sentences of data to transmit this way, e.g. Furuno FA-150. I do not know if any affordable or Class B devices will do it.

Furuno FA-70, a Class B device,  list ABM and BBM as Input sentences in the [[https://www.furuno.it/docs/OPERATOR_MANUAL/OME45150A1_FA70.pdf|manual]] in SOTDMA mode only, but says something about "acknowledgement", so I'm not sure. It costs nearly 1000 GBP from an online shop. 

The Ocean Signal ATB1 {{ :912s-02692-atb1-user-manual-v01.11-en.pdf |manual}} says it supports ABM and BBM sentences //in and out// on NMEA0183, and equivalent looking PGNs on NMEA2000. It is a Class B device with SOTDMA. It is also one of the cheaper and more popular devices, but I have anecdata that it is unreliable.

[[maiana|Maiana]] is an Open Source AIS Transponder.

OpenCPN will now decode weather data sent over AIS binary messages: [[https://www.cruisersforum.com/forums/f134/question-what-is-this-ais-target-282096.html#post3851100|see here]].

====== RF ======

Tune aerials to 162 MHz.

  * Channel A 161.975 MHz (87B)
  * Channel B 162.025 MHz (88B)


===== VDES - VHF Data Exchange System =====

Apparently people noticed that AIS could be used for things like weather data, lock water levels, and AtoN battery levels, and AIS is becoming busier. So they decided to expand the system and create VDES. This will use some of the current VHF telephony channels for data. It seems to be defined already but not yet in use.

===== Links =====

[[https://www.itu.int/dms_pubrec/itu-r/rec/m/R-REC-M.1371-5-201402-I!!PDF-E.pdf|AIS Standard: ITU-R M.1371-5]]

https://publications.vtt.fi/julkaisut/muut/2010/AIS_Binary_Messages-Develpoments_in_the_Baltic_and_Progress_in_IMO.pdf

A paper: [[https://www.transnav.eu/Article_Sharing_Ships%E2%80%99_Weather_Data_via_Tetreault,53,987.html|Sharing Ships’ Weather Data via AIS]]

[[https://www.iala-aism.org/technical/connectivity/vdes-vhf-data-exchange-system/|IALA VDES FAQ]]

[[https://www.itu.int/dms_pubrec/itu-r/rec/m/R-REC-M.2092-0-201510-I%21%21PDF-E.pdf|Recommendation ITU-R M.2092-0]] - VDES, looks like a vague early specification, at a quick glance.

[[https://navcen.uscg.gov/sites/default/files/pdf/AIS/IALA_G1117_Ed2_VHF_Data_Exchange_System_VDES_Overview_Dec2017.pdf|IALA VDES Overview]]