RTLSDR-Airband

RTLSDR Airband is a Linux program intended for AM/NFM voice channels reception and online streaming to services such as liveatc.net

Features

• Multichannel mode - decode up to eight AM or NFM channels per dongle (within bandwidth frequency range)
• Scanner mode - decode unlimited number of AM and/or NFM channels with frequency hopping in a round-robin fashion (no frequency range limitations)
• Decode multiple dongles simultaneously
• Auto squelch and Automatic Gain Control
• MP3 encoding
• Stream to Icecast or SHOUTcast server
• Record to local MP3 files (continuously or skipping silence periods)
• Multiple streaming/recording destinations per channel
• Mixing several channels into a single audio stream (both mono and stereo mixing is supported)

Performance

x86

• ~4% per dongle on i5-2430m at 2.1 GHz

Raspberry Pi

• FFT using Broadcom Videocore IV GPU
• No overclock required when using 1 dongle plus another dongle running dump1090
• Turbo overclock setting recommended on RPi V1 when using 2 dongles (no overclocking is necessary on RPi V2)

Other ARMv7-based platforms

• FFT using main CPU
• Tested on Cubieboard2 - ~50% CPU when using 1 dongle

Demo

Building

Linux (Raspbian)

• Install RTLSDR library (http://sdr.osmocom.org/trac/wiki/rtl-sdr):

   sudo apt-get update
   sudo apt-get install git gcc autoconf make libusb-1.0-0-dev libtool
   cd
   git clone git://git.osmocom.org/rtl-sdr.git
   cd rtl-sdr/
   autoreconf -i
   ./configure
   make
   sudo make install
   sudo ldconfig
   sudo mv $HOME/rtl-sdr/rtl-sdr.rules /etc/udev/rules.d/rtl-sdr.rules
  

• Blacklist DVB drivers to avoid conflict with SDR driver - before connecting the USB dongle create file /etc/modprobe.d/dvb-blacklist.conf with text editor (eg. nano) and add the following lines:

   blacklist r820t
   blacklist rtl2832
   blacklist rtl2830
   blacklist dvb_usb_rtl28xxu
  

• Download a release tarball from from https://github.com/szpajder/RTLSDR-Airband/releases and unpack it. Example:

   tar xvfz RTLSDR-Airband-1.0.0.tar.gz
   cd RTLSDR-Airband-1.0.0
  

  Alternatively you can pull the latest code from git:

   git clone https://github.com/szpajder/RTLSDR-Airband.git
   cd RTLSDR-Airband/
  

  If you want cutting-edge features which didn't make it into a release yet, checkout the unstable branch:

   git checkout unstable
  

  Be aware that it might be experimental, buggy, or at least, untested.

• Install necessary dependencies:

   sudo apt-get install libmp3lame-dev libvorbis-dev libshout-dev libconfig++-dev
  

• Set the build options and run make. Available build options:

  PLATFORM=platform_name - selects the hardware platform. This option is mandatory. See below.

  NFM=1 - enables NFM support. By default, NFM is disabled.

  Warning: Do not enable NFM, if you only use AM (especially on low-power platforms, like RPi). This incurs performance penalty, both for AM and NFM.

  Examples:

  Build a binary for RPi version 1 (ARMv6 CPU, Broadcom VideoCore GPU):

   PLATFORM=rpiv1 make
  

  Same platform, but with NFM support enabled:

   PLATFORM=rpiv1 NFM=1 make
  

  Building for RPi V2 (ARMv7 CPU, Broadcom VideoCore GPU), with NFM support:

   PLATFORM=rpiv2 NFM=1 make
  

  Building for other ARM-based platforms without VideoCore GPU (FFTW3 library is needed in this case), NFM disabled:

   sudo apt-get install libfftw3-dev
   PLATFORM=armv7-generic make		# for ARMv7 platforms, like Cubieboard
  

  PLATFORM=armv8-generic make # for 64-bit ARM platforms, like Odroid C2

  Building for generic x86 CPU (FFTW3 library is needed in this case), NFM enabled:

   sudo apt-get install libfftw3-dev
   PLATFORM=x86 NFM=1 make
  

• Install the software:

   make install
  

  By default, the binary is installed to /usr/local/bin/rtl_airband.

• Edit the configuration file to suit your needs. See chapter "Configuring" below.

• You need to run the program with root privileges - for example:

   sudo /usr/local/bin/rtl_airband
  

  The program runs as a daemon (background process) by default, so it may look like it has exited right after startup. Diagnostic messages are printed to syslog (on Raspbian they are directed to /var/log/messages by default).

• If you wish to start the program automatically at boot, you can use example startup scripts from init.d subdirectory. Example for Debian / Raspbian:

   sudo cp init.d/rtl_airband-debian.sh /etc/init.d/rtl_airband
   sudo chmod 755 /etc/init.d/rtl_airband
   sudo update-rc.d rtl_airband defaults
  

Configuring

By default, the configuration is read from /usr/local/etc/rtl_airband.conf. Refer to example configuration files in the config/ subdirectory. basic_multichannel.conf is a good starting point. When you do make install, this file will get copied to /usr/local/etc/rtl_airband.conf (unless you already have your own config file installed). All available config parameters are mentioned and documented in config/reference.conf.

Command line options

rtl_airband accepts the following command line options:

-h                      Display this help text and exit
-v                      Display version and exit
-f                      Run in foreground, display textual waterfalls
-c <config_file_path>   Use non-default configuration file
-Q                      Use quadri correlator for FM demodulation (default is atan2)
                        (this option is available only if rtl_airband was compiled
		    with NFM support enabled)

Troubleshooting

Syslog logging is enabled by default, so first of all, check the logs for any error messages, for example: tail /var/log/messages. Common problems:

• Problem 1: the program fails to start on RPi. It dumps the error message:

  Dec 27 08:58:00 mypi rtl_airband[28876]: Can't open device file /dev/vcio: No such file or directory

  Solution: you need to create /dev/vcio device node. To do that, you need to know the correct major number. Older Raspbian kernels (before 4.0) used 100, newer ones use 249, so first check that:

  pi@mypi:~$ grep vcio /proc/devices 249 vcio

  This means /dev/vcio must be created with a major number of 249:

  sudo mknod /dev/vcio c 249 0

  In other case, substitute 249 with the number taken from grep output above.

• Problem 2: the program fails to start on RPi. It dumps the error message:

  Dec 27 08:58:00 mypi rtl_airband[28876]: Can't open device file /dev/vcio: No such device or address

  or:

  Dec 27 08:58:00 mypi rtl_airband[28876]: mbox_property(): ioctl_set_msg failed: Inappropriate ioctl for device

  This means you have /dev/vcio, but its major number is probably wrong:

  pi@mypi:~$ ls -l /dev/vcio crw-rw---T 1 root video 100, 0 Jan 1 1970 /dev/vcio

  This one was created with a major number of 100. grep vcio /proc/devices shows the correct number - if it's different, then delete it (sudo rm /dev/vcio) and create it again (see above).

• Problem 3: the program fails to start on RPi. It dumps the error message:

  Unable to enable V3D. Please check your firmware is up to date.

  Most often this is a problem of people who changed the default CPU:GPU memory split by setting gpu_mem to something lower than 64 MB. Check your /boot/config.txt and remove the gpu_mem setting altogether, if it's there. Then save the file and reboot the Pi.

• When the program is running in scan mode and is interrupted by a signal (eg. ctrl+C is pressed when run in foreground mode) it crashes with segmentation fault or spits out error messages similar to these:

  r82xx_write: i2c wr failed=-1 reg=1a len=1 r82xx_set_freq: failed=-1 rtlsdr_demod_write_reg failed with -1 rtlsdr_demod_read_reg failed with -7

  This is due to a bug in libusb versions earlier than 1.0.17. Upgrade to a newer version.

License

Copyright (C) 2015-2016 Tomasz Lemiech [email protected]

Based on original work by Wong Man Hang [email protected]

This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License along with this program. If not, see http://www.gnu.org/licenses/.

Open Source Licenses

###fftw3

• Copyright (c) 2003, 2007-14 Matteo Frigo
• Copyright (c) 2003, 2007-14 Massachusetts Institute of Technology
• GNU General Public License Version 2

###gpu_fft BCM2835 "GPU_FFT" release 2.0 Copyright (c) 2014, Andrew Holme. All rights reserved.

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###libmp3lame

•  Copyright (c) 1999 Mark Taylor
  

•  Copyright (c) 2000-2002 Takehiro Tominaga
  

•  Copyright (c) 2000-2011 Robert Hegemann
  

•  Copyright (c) 2001 Gabriel Bouvigne
  

•  Copyright (c) 2001 John Dahlstrom
  

• GNU Library General Public License Version 2

###libogg Copyright (c) 2002, Xiph.org Foundation

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• Neither the name of the Xiph.org Foundation nor the names of its contributors may be used to endorse or promote products derived from this software without specific prior written permission.

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###librtlsdr

• Copyright (C) 2012 by Steve Markgraf [email protected]
• GNU General Public License Version 2

###libshout

• Copyright (C) 2002-2004 the Icecast team [email protected]
• GNU Library General Public License Version 2

###libvorbis Copyright (c) 2002-2008 Xiph.org Foundation

Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:

• Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.

• Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution.

• Neither the name of the Xiph.org Foundation nor the names of its contributors may be used to endorse or promote products derived from this software without specific prior written permission.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

###libconfig Copyright (C) 2005-2014 Mark A Lindner

This library is free software; you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License published by the Free Software Foundation; either version 2.1 of the License, or (at your option) any later version.

This library is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details.