Dump1090-mutability v1.15~dev and RTL-SDR V3 Bias-T Auto Switch-ON


#1

The method posted on the RTL-SDR Blog is applicable to dump1090-fa only.
It does not apply to dump1090-mutability v1.15~dev, as ALL the dump1090-mutability service files (dump1090-mutability.service) are automatically generated by systemd-sysv-generator, and all the changes made by user are overwritten at restart / reboot.

However as the systemd-sysv-generator generates dump1090-mutability.service by reading from file `/etc/init.d/dump1090-mutability, I have added bias-t start and logging script in that file, and it works OK.

STEP-1

Build package rtl_biast

#First installed Packages needed to build and to fulfill dependencies
sudo apt-get install git  
sudo apt-get install cmake   
sudo apt-get install libusb-1.0   

#Now build rtl_biast
git clone https://github.com/rtlsdrblog/rtl_biast   
cd rtl_biast   
mkdir build   
cd build   
cmake ..   
make   


#TEST-1
cd src   
./rtl_biast -b 1   

usb_claim_interface error -6


#TEST-2
sudo systemctl stop dump1090-mutability   

./rtl_biast -b 1   
Found Rafael Micro R820T tuner

STEP-2:

(1) Open file /etc/init.d/dump1090-mutability in editor.

 sudo nano /etc/init.d/dump1090-mutability

(2) In the file opened, scroll down to following portion of code
(You can quickly reach there by pressing Ctrl+w, then typing do_start, then pressing Enter Key).

# Function that starts the daemon/service
#
do_start()
{
        # Return
        #   0 if daemon has been started
        #   1 if daemon was already running
        #   2 if daemon could not be started

(3) Insert following 2 lines

/home/pi/rtl_biast/build/src/rtl_biast -b 1 >> /var/log/biast.log 2>&1
date >> /var/log/biast.log

The lines should be inserted at location shown below:

# Function that starts the daemon/service
#
do_start()
{

/home/pi/rtl_biast/build/src/rtl_biast -b 1 >> /var/log/biast.log 2>&1
date >> /var/log/biast.log

        # Return
        #   0 if daemon has been started
        #   1 if daemon was already running
        #   2 if daemon could not be started

(4) Save file (Ctrl+o) and Close editor (Ctrl+x)

(5) Reload daemon to incorporate changes, then restart dump1090-mutability.

sudo systemctl daemon-reload
sudo systemctl restart dump1090-mutability

Check log

cat /var/log/biast.log
Found Rafael Micro R820T tuner
Tue May  1 14:25:06 EDT 2018

.

Explanation of code:
/home/pi/rtl_biast/build/src/rtl_biast -b 1” switches on the bias t
>> /var/log/biast.log 2>&1” sends output (stdout+stderr) to file /var/log/biast.log
date >> /var/log/biast.log” timestamps the log

.

If you are interested only in switching-on the bias-t, and are not interested in creating biast log, then only one short line (i.e. /home/pi/rtl_biast/build/src/rtl_biast -b 1) need to be added as shown below:

# Function that starts the daemon/service
#

do_start()
{

/home/pi/rtl_biast/build/src/rtl_biast -b 1

        # Return
        #   0 if daemon has been started
        #   1 if daemon was already running
        #   2 if daemon could not be started