NAME

       rtl_fm - a simple FM demodulator for RTL2832 based DVB-T receivers

DESCRIPTION

       Uses  a  re-purposed  DVB-T receiver as a software defined radio to receive narrow band FM
       signals and demodulate to audio. Written for  and  incorporated  in  the  osmocom  rtl-sdr
       project.

       Narrowband  FM  is  commonly  used  by  public  service  agencies  and commercial dispatch
       operations in the VHF and UHF bands.  Also can demodulate Wideband FM,  as  found  in  the
       88-108  MHz  FM  broadcast  band.   Experimental  options  include  AM,  LSB,  USB and DSB
       demodulation.

       Much software is available for the RTL2832. Most of the user-level packages  rely  on  the
       librtlsdr library which comes as part of the rtl-sdr codebase. This codebase contains both
       the library itself and also a number of command line  tools  such  as  rtl_test,  rtl_sdr,
       rtl_tcp, and rtl_fm. These command line tools use the library to test for the existence of
       RTL2832 devices and to perform basic data transfer functions to and from the device.

       Because most of the RTL2832 devices are connected using USB, the librtlsdr library depends
       on the libusb library to communicate with the device.

USAGE

       With a suitable antenna for receiving the signal attached to the rtl-sdr supported device,
       this program will output the digital audio data decoded from that signal. The data can  be
       listened  to  by  piping  to  Sox or aplay applications to play the stream on the computer
       sound card.

SYNOPSIS

       rtl_fm [-f freq] [-options] [filename]

OPTIONS

       -f frequency_to_tune_to [Hz]
               use multiple -f for scanning, (requires squelch)
               ranges supported, -f 118M:137M:25k

       [-M modulation (default: fm)]
               fm, wbfm, raw, am, usb, lsb
               wbfm == -M fm -s 170k -o 4 -A fast -r 32k -l 0 -E deemp
               raw mode outputs 2x16 bit IQ pairs

       -s sample_rate (default: 24k)

       -d device_index (default: 0)

       -g tuner_gain (default: automatic)

       -l squelch_level (default: 0/off)

       -o oversampling (default: 1, 4 recommended)
               for fm squelch is inverted

       [-o oversampling (default: 1, 4 recommended)]

       -p ppm_error (default: 0)

       [-E enable_option (default: none)]
               use multiple -E to enable multiple options
                  edge:   enable lower edge tuning
                  dc:     enable dc blocking filter
                  deemp:  enable de-emphasis filter
                  direct: enable direct sampling
                  offset: enable offset tuning

       filename ('-' means stdout)
               omitting the filename also uses stdout

Experimental options

       [-r resample_rate (default: none / same as -s)]

       [-t squelch_delay (default: 10)]
                +values will mute/scan, -values will exit

       [-F fir_size (default: off)]
                  enables low-leakage downsample filter
                  size can be 0 or 9.  0 has bad roll off

       -A std/fast/lut choose atan math (default: std)

       filename
               (a '-' dumps samples to stdout)
               (omitting the filename also uses stdout)

EXAMPLES

       Produces signed 16 bit ints, use Sox or aplay to hear them.

       rtl_fm ... - | play -t raw -r 24k -es -b 16 -c 1 -V1 -
                                | aplay -r 24k -f S16_LE -t raw -c 1
                       -M wbfm  | play -r 32k ...

       rtl_fm ...  -s 22050 - | multimon -t raw /dev/stdin

SEE ALSO

       RTL-SDR wiki documentation: http://sdr.osmocom.org/trac/wiki/rtl-sdr

       Rtl_fm Guide: http://kmkeen.com/rtl-demod-guide/

       sox(1), play(1), aplay(1)

       Other rtl-sdr programs:

       rtl_adsb(1), rtl_eeprom(1), rtl_sdr(1), rtl_tcp(1), rtl_test(1)

AUTHOR

       This manual page was written by Maitland Bottoms for the Debian project (but may  be  used
       by others).

COPYRIGHT

       Copyright (c) 2013 A. Maitland Bottoms <bottoms@debian.org>

       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.