RTLSDR Plugin for OpenCPN
=======================================
Implement rtlsdr ability for opencpn to receive ais messages

Configuration using rtl_fm and aisdecoder
=================================================

First, you must be able to run rtl_fm and aisdecoder applications to recieve ais data.
This is independent from the plugin itself, the plugin merely runs these programs
piping the data from rtl_fm to aisdecoder and then into opencpn.  The plugin
can also perform automatic calibration.

For windows, I have compiled the needed programs using mingw, and
provided binaries already (in the buildwin/bin directory)
You must download the rtlsdr_winutilites.zip file available from sourceforge
and extract it here to compile from source on windows and correctly build packages.

Otherwise you must compile from source and install:

git clone git://git.osmocom.org/rtl-sdr.git
cd rtl-sdr
mkdir build
cd build
cmake ..
make
sudo make install

wget http://www.aishub.net/downloads/aisdecoder.tar.gz
tar zxvf aisdecoder
cd aisdecoder
cmake -DCMAKE_BUILD_TYPE=release .
make
sudo cp aisdecoder /usr/local/bin

Test with:
rtl_fm -f 161975000 -p 35 -s 48k | aisdecoder -h 127.0.0.1 -p 10110 -a file -c mono -d -f /dev/stdin

be sure to try all possible values for -p!  this program is very picky and your value must be +- 7
of the correct value to get messages (Range +- 128)  the exact correct value gives many more messages.
The plugin provides an automatic detection routine.

At this point you can simply add a udp data connection on port 10110 and not use the plugin, but the
plugin automatically invokes the programs, and provides other control.

Configuration using gnuradio
=================================================

The plugin also can run gnuradio to decode ais data, but I do not provide
binaries to do this under windows.

apt-get install libboost-all-dev uhd swig
apt-get install gnuradio gnuradio-dev
git clone git://git.osmocom.org/gr-osmosdr
cd gr-osmosdr
if gnuradio 3.6 is installed "git checkout gr3.6"
mkdir build
cd build
cmake ..
make -j2
sudo make install

sudo apt-get install libcppunit-dev libfftw3-dev python-numpy
git clone https://github.com/bistromath/gr-ais.git
cd gr-ais
for gnuradio 3.6 "git checkout 1381ceca81b0cf238eeb81da9cd77189da74022a"
mkdir build
cd build
cmake ..
make
sudo make install

Compiling
=========
* git clone git://github.com/seandepagnier/rtlsdr_pi.git

Under windows, you must find the file "opencpn.lib" (Visual Studio) or "libopencpn.dll.a" (mingw) which is built in the build directory after compiling opencpn.  This file must be copied to the plugin directory.

Build as normally:

* mkdir build
* cd build
* cmake ..
* make
* make install

License
=======
The plugin code is licensed under the terms of the GPL v3 or, at your will, later.