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.