ElCheapoAIS

AIS receiver with DIY antenna and cheap RTL-SDR tuner

Quick guide

1. You need: Raspberry Pi, USB RTL SDR tuner, materials for building the antenna
2. Craft the antenna (see instructions below)
3. Install Raspbian on the RPi (tested with Stretch 4.14 Lite)
4. Prepare the destination of the AIS data (i.e. create AISHub account: http://www.aishub.net/join-us)
5. Execute wget -q -O - https://git.io/fpVRc | sudo bash (Alternatively, you can ignore step 5 and 6 and follow the procedure at the end of this README)
6. Follow the instructions (prepare, calibrate and install using the account details received in step 4)
7. Profit?

Hardware

• Tuner https://www.ebay.com/itm/USB2-0-DAB-FM-DVB-T-RTL2832U-R820T2-SDR-RTL-SDR-Dongle-Stick-Digital-TV-Tun-W8M8/283032648261
• Antenna

Build the antenna

Measurements, examples and building instructions are available here: https://m0ukd.com/calculators/quarter-wave-ground-plane-antenna-calculator/. The following measurements are for a 162 Mhz antenna (for best results build one around that frequency):

You can 3d print the center holder: https://www.thingiverse.com/thing:3099905

Software

Windows (Testing)

• AISRecWinFull https://sites.google.com/site/feverlaysoft/home
• OpenCPN
  • Set the same ip and port in OpenCPN and AISRecWinFull, and start the later

Ubuntu

If your device is constantly in use even though you're not using it, it's probably used by the DVB kernel driver. To use it as an SDR receiver run the following as root before pluggin in your device:

echo "blacklist dvb_usb_rtl28xxu" >> /etc/modprobe.d/blacklist.conf

Raspbian/Raspberry Pi

Using kalibrate-rtl and rtl-ais.

Setup

  sudo apt install build-essential libtool m4 automake libfftw3-dev automake autoconf
  git clone https://github.com/steve-m/kalibrate-rtl
  cd kalibrate-rtl
  ./bootstrap && CXXFLAGS='-W -Wall -O3'
  ./configure
  make
  sudo make install

Now scan for base stations

  kal -g 42 -e 22 -s 850
  kal -g 42 -e 22 -s 900
  etc…

Example output

Find ppm error using the strongest channel from previous attempts

  kal -e 41 -c <strongest channel> -v

Example output

Copy the ppm value at the end of the output from the last step. You can write decimals in the -p argument, but it will parsed as integer.

Compile rtl_ais

  sudo apt install git librtlsdr-dev libusb-dev libpthread-workqueue-dev
  git clone https://github.com/dgiardini/rtl-ais 		
  cd rtl-ais
  make

Run rtl_ais

  sudo ./rtl_ais -n -h <UDP_SERVER> -P <PORT_SERVER> -p <PPM_ERROR> -g 60 -S 60

Done!

Test

sudo ./rtl_ais -n -h <UDP_SERVER> -P <PORT_SERVER> -p <PPM_ERROR> -g 60 -S 60