softfm-jj1bdx: Software decoder for FM broadcast radio with RTL-SDR (for MacOS and Linux)

• This repository is forked from SoftFM

Modification of this fork from the original SoftFM

• Remove ALSA dependency to make this software run on macOS
• Fix other glitches on macOS
• Merge ngsoftfm code
• Add quiet mode

macOS usage example (also works on Linux)

./softfm -f 88100000 -g 8.7 -b 1.0 -q -R - | \
    play -t raw -esigned-integer -b16 -r 48000 -c 2 -q -

Original README begins here

SoftFM is a software-defined radio receiver for FM broadcast radio. It is written in C++ and uses RTL-SDR to interface with RTL2832-based hardware.

This program is mostly an experiment rather than a useful tool. The purposes of SoftFM are

• experimenting with digital signal processing and software radio;
• investigating the stability of the 19 kHz pilot;
• doing the above while listening to my favorite radio station.

Having said that, SoftFM actually produces pretty good stereo sound when receiving a strong radio station. Weak stations are noisy, but SoftFM gets much better results than rtl_fm (bundled with RTL-SDR) and the few GNURadio-based FM receivers I have seen.

SoftFM provides:

• mono or stereo decoding of FM broadcasting stations
• real-time playback to soundcard or dumping to file
• command-line interface (no GUI, no visualization, nothing fancy)

SoftFM requires:

• Linux
• C++11
• RTL-SDR library (http://sdr.osmocom.org/trac/wiki/rtl-sdr)
• supported DVB-T receiver
• medium-fast computer (SoftFM takes 25% CPU time on my 1.6 GHz Core i3)
• medium-strong FM radio signal

For the latest version, see https://github.com/jorisvr/SoftFM

Installing

The Osmocom RTL-SDR library must be installed before you can build SoftFM. See http://sdr.osmocom.org/trac/wiki/rtl-sdr for more information. SoftFM has been tested successfully with RTL-SDR 0.5.3.

To install SoftFM, download and unpack the source code and go to the top level directory. Then do like this:

$ mkdir build
$ cd build
$ cmake ..

# CMake tries to find librtlsdr. If this fails, you need to specify
# the location of the library in one the following ways:
#
#  $ cmake .. -DCMAKE_INSTALL_PREFIX=/path/rtlsdr
#  $ cmake .. -DRTLSDR_INCLUDE_DIR=/path/rtlsdr/include -DRTLSDR_LIBRARY_PATH=/path/rtlsdr/lib/librtlsdr.a
#  $ PKG_CONFIG_PATH=/path/rtlsdr/lib/pkgconfig cmake ..

$ make

$ ./softfm -f <radio-frequency-in-Hz>

# ( enjoy music )

License

GPL2 (although some code specifies GPL3).

NGSoftFM, copyright (C) 2015, Edouard Griffiths, F4EXB

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 2 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/gpl-2.0.html

SoftFM, copyright (C) 2013, Joris van Rantwijk

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 2 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/gpl-2.0.html