New AIS receiver: dAISy-catcher

[jvde-github]

Hi all,

just want to point out a new AIS receiver we developed together with Wegmatt, the dAISy-catcher. More information on specs and documentation can be found here. The idea was to combine the advantages of an SDR-based AIS receiver (reception quality, flexibility) with the advantages of a hardware solution (plug-and-play solution as either USB serial receiver or Raspberry Pi HAT, low power consumption, accurate signal levels and timestamps, and AIS-tuned filters for robustness).

The new device can be run with AIS-catcher using serial device as input driver.

[astuder]

Hello 👋

I worked with Jasper on this project, mainly working on the hardware while Jasper did his DSP magic.

Based on side-by-side tests, performance is comparable to running AIS-catcher with a good SDR like the Airspy HF+. At the same time, the dAISy-catcher uses about half the power of just the SDR, and that's with doing all the compute heavy work on the receiver instead of the host computer.

My favorite feature of the dAISy-catcher is the precision timestamps, though we're still looking for a good real-world application for that data. Triangulation is an obvious one, but it turned out to be trickier than expected due to the impact of topography and atmospheric conditions. The below plot shows how time-of-arrival (Y-axis) correlates with distance (X-axis), but also the differences between AIS transponders. The dotted line is expected time based on speed of light.

Happy to answer any questions.

You're also welcome to contact me by email (see profile) if you want to pitch an interesting, resource-limited project that needs a better AIS receiver, or have an application for the precision timestamps.

[ymmengin]

Hi Jasper & Adrian,

Great news. I just ordered one yesterday to replace a dAISy HAT and Uputronics LNA running on a RPi5.

Thanks,
Yves

[astuder]

Thanks! Let us know how it goes.

PS: Big Brother told me that you forgot the 16mm stacking kit. I did include one with your package. :)

[ymmengin]

Perfect! Indeed, I pulled the trigger too fast.
From the documentation, it looks like the dAISy-catcher is 12 mm tall. What's the height above USB ports?

[astuder]

This picture is with the 16mm stand-offs, which leaves a bit of room above the active cooler for the air to circulate. If the circuit board would expand over the ports on the right, it would sit flush on top of the USB ports with maybe 0.1-0.2mm to spare. The plastic body of the 2x40 header provided with the 16mm kit is the same height as the more commonly available double-shrouded stacking headers with long pins.

For comparison, the dAISy HAT sits 11mm above the circuit board of the Pi.