tirsdag den 13. marts 2012

Boat project: AIS SART Alarm

This will be a small box to attach to your AIS receivers NMEA output. It will scan the output stream for type type 14 AIVDM messages coming from an Ais SART such as the easyRESCUE. Alternatively MMSI numbers in the 970xxxxxx range will also trigger an alarm.

The decoding is done with an Atmel ATtiny to roughly $ 1,- which will drive an LED and a piezo buzzer. A pushbutton is attached to an input pin.
  • During normal operation the LED will blink slowly when AIS messages are seen.
    A push button press will test the buzzer.
  • When a SART transmission is detected, the LED will blink fast and the buzzer is activated.
    A pushbutton press will disable the buzzer, but the LED will keep blinking fast.
    Additional presses will toggle the buzzer.
  • When the SART in question (by MMSI) stops transmitting, the buzzer will be re-armed.
This can all be built for appx. ten dollars. AIS SART detectors retail for about 500 ...

Watch this space for a diagram coming up soon.

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