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  1. AIS Decoding with an RTL-SDR Blog v3 Dongle

    At the conclusion of my last AIS blog post, I noted that the AIS receiving station I had set up was not sustainable for the long term. It was using a full hardware radio, and the software was running in a Windows 7 virtual machine on my personal laptop. Since AIS decoding is not super useful only when my laptop is powered on, a new station setup was needed.

    One option would be buying a dedicated Raspberry Pi with a dAISy Hat receiver. It's a dual-channel receiver that spits out UART serial NMEA frames to the Raspberry Pi, and costs $70, plus a Pi for $35. But that's a lot of money for something that I don't really get any ...

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  2. Decoding AIS Signals for Marine Monitoring

    Automatic Identification System is a system for boats to broadcast their location. This is very helpful in congested waters, such as in the San Francisco Bay, where many ferries, huge container ships, and small pleasure craft are trying to avoid each other. Onboard digital chart plotters can show nearby ships, their heading, speed, and expected position a few minutes from now. Early AIS transmitters were very expensive, but the new generation of Class B transmitters are actually pretty inexpensive.

    AIS operates on two frequencies, Marine VHF channels 87B and 88B. These are the high-side duplex frequencies of channel 87 and 88, and they are 161.975 and 162.025 MHz. The data link layer is 9600 baud GMSK, packet length ...

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