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

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

       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.

RTL-SDR                                               0.5.0                                          rtl_adsb(1)

       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.

       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

       [-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)

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

       -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

       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)

rtl_fm[-ffreq][-options][filename]

       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.