The .NET Micro Framework and AIS

As it says on their website, the .NET Micro Framework is .NET for small and resource constrained devices. It offers a complete and innovative development and execution environment that brings the productivity of modern computing tools to this class of devices.

So we’ve tried it with AIS. We used the FEZ Cobra from GHI Electronics with the 3.5” touch screen:

cobra1       cobra2

Then we added a GPS receiver and implemented an embedded AIS vessel plotter. The GPS we used is the FV-M8 model from San Jose Navigation:


The device we used runs on 6V. This can be provided by batteries or an adapter. The GPS also needs a small backup battery. Without an external backup battery, the GPS will execute a cold start after every turn on. Anything between 2V and 5V should do to achieve fast GPS start-ups.

We wired the GPS to the UEXT connector pins (3.3V, GND, COM1TX and COM1RX) and supplied the backup battery power as mentioned before. Optionally, an external GPS antenna could be used, or the position could be retrieved from an external GPS device.

The vessel plotter we implemented supports dynamic, static and voyage related information, plots vessels in vicinity of your own position, has 9 range scales (0.1 Nm to 10 Nm), has a configurable proximity alarm (.05 Nm to 10 Nm with mandatory confirmation), has “target lost” indication, shows extended ship information and visualizes Rate Of Turn, Heading, Course Over Ground and projected routes of vessels.

WP_000345       WP_000346

The FEZ Cobra board has several options for receiving an AIS stream. With the ethernet port or the optional Wi-Fi module, the AIS stream could be dispatched directly to the device, for example using AIS Dispatcher.

Since the EMX module supports USB Host, another option could be to connect a receiver – such as the MarineGadget AIS receiver – to the USB port of the device. These approaches would require a .NET Micro Framework AIS parser implementation to process the AIS stream on the device.

Alternatively, the AIS data could be retrieved using web service calls. We will use this approach and make REST HTTP calls to our AIS web services. Again, there are several options to do this. We could add a wireless module and call the services over Wi-Fi, we could add a cellular radio module to reach the services over the internet, or we could just use the ethernet port on the device to connect to services on a LAN or on the internet, which is what we did here.

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