Software to turn the RTL2832U into a SDR receiver
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.TH "rtl_adsb" 1 "0.5.0" RTL-SDR "User Commands"
rtl_fm \- a simple FM demodulator for RTL2832 based DVB-T receivers
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.
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.
.B rtl_fm [-f freq] [-options] [filename]
.IP "-f frequency_to_tune_to [Hz]"
use multiple -f for scanning, (requires squelch)
ranges supported, -f 118M:137M:25k
.IP "[-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
.IP "-s sample_rate (default: 24k)"
.IP "-d device_index (default: 0)"
.IP "-g tuner_gain (default: automatic)"
.IP "-l squelch_level (default: 0/off)"
.IP "-o oversampling (default: 1, 4 recommended)"
for fm squelch is inverted
.IP "[-o oversampling (default: 1, 4 recommended)]"
.IP "-p ppm_error (default: 0)"
.IP "[-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
.IP "filename ('-' means stdout)"
omitting the filename also uses stdout
.SH Experimental options
.IP "[-r resample_rate (default: none / same as -s)]"
.IP "[-t squelch_delay (default: 10)]"
+values will mute/scan, -values will exit
.IP "[-F fir_size (default: off)]"
enables low-leakage downsample filter
size can be 0 or 9. 0 has bad roll off
.IP "-A std/fast/lut choose atan math (default: std)"
.IP filename
(a '-' dumps samples to stdout)
(omitting the filename also uses stdout)
Produces signed 16 bit ints, use Sox or aplay to hear them.
.IP "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 ...
.IP "rtl_fm ... -s 22050 - | multimon -t raw /dev/stdin"
RTL-SDR wiki documentation:
Rtl_fm 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)
This manual page was written by Maitland Bottoms
for the Debian project (but may be used by others).
Copyright (c) 2013 A. Maitland Bottoms <>
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
GNU General Public License for more details.