In RTL-SDR Blog V3 dongle, the Bias-T should be switched on before decoder software starts. This problem occures in dump1090-fa and dump1090-mutability also. The solution was easy as the Bias-T startup software rtl_biast was a separate package, so in Service file following line was added:
[Service]
ExecStartPre=/home/pi/rtl_biast/build/src/rtl_biast -b 1
In case of AIS-catcher, the bias-t turn on off software is integral part of the AIS-cacher binary, so the ExecStartPre method cannot be used directly, unless a stand-alone rtl-biast package is built and installed, and Service file modified, like is done for dump1090-fa and dump1090-mutability.
Following method overcomes this issue of AIS-catcher biast.
(1) Building stand-alone rtl_biast
(2) Modifying aiscatcher’s Service file to add ExecStartPre=
(3) Delete BIASTEE on from aiscatcher.cfg file to avoid conflict
STEP (1): Install dependencies
$ sudo apt update
$ sudo apt install git cmake build-essential libusb-1.0-0-dev
STEP (2): Clone Source Code of Biast and Build It
## Enter AIS-catcher folder
cd /usr/share/aiscatcher
## Clone source-code of biast from Github and make executeable
$ sudo git clone https://github.com/rtlsdrblog/rtl_biast
$ cd rtl_biast
$ sudo mkdir build
$ cd build
$ sudo cmake .. -DDETACH_KERNEL_DRIVER=ON
$ sudo make
STEP (3): Check:
$ ls /usr/share/aiscatcher/rtl_biast/build/src
CMakeFiles librtlsdr.a librtlsdr.so.0.5git
cmake_install.cmake librtlsdr.so Makefile
libconvenience_static.a librtlsdr.so.0 rtl_biast
STEP (4): Modify aiscatcher’s Service file
$ sudo nano /lib/systemd/system/aiscatcher.service
## Add following line ABOVE the line starting with ExecStart=
ExecStartPre=/usr/share/aiscatcher/rtl_biast/build/src/rtl_biast -b 1 -d 0
NOTE: If you are using more than one dongle, run command rtl_test -t to determine device index of AIS Dongle (0, 1, 2,…). If the AIS dongle has index 1, then in above command change d 0 to d 1
BEFORE Adding New Line
AFTER Adding New Line
STEP (5): Delete “BIAST on” from AIS-Catcher config
STEP (6):
REBOOT PI