DVB-T USB SDR
From charlesreid1
Overview
Plug It In
First thing is to hook up the antenna to the USB dongle, and plug the USB dongle into the computer, and make sure the computer sees it:
$ lsusb | grep -i rtl Bus 001 Device 003: ID 0bda:2838 Realtek Semiconductor Corp. RTL2838 DVB-T
Get Software
Gnu Radio
First thing is to install gnuradio.
apt-get install gnuradio
Cmake
Yer gonna need Cmake.
apt-get install cmake
Boost/GSL Development
Then we'll install the Boost and GSL headers/development libraries for building scripts:
apt-get install libboost-1.49 libboost-dev libgsl0-dev
(Note that both of these were found using aptitude search [keyword]).
RTL-SDR Project
Next, clone into the rtl-sdr repository:
git clone git://git.osmocom.org/rtl-sdr.git
This project contains the software needed to interpret the raw I/Q packets sent from the antenna to the computer.
Now build the RTL-SDR project:
mkdir build cd build cmake ../
LibUSB Error
cmake ../ -- The C compiler identification is GNU 4.7.2 -- Check for working C compiler: /usr/bin/gcc -- Check for working C compiler: /usr/bin/gcc -- works -- Detecting C compiler ABI info -- Detecting C compiler ABI info - done -- Build type not specified: defaulting to release. -- Extracting version information from git describe... -- Found PkgConfig: /usr/bin/pkg-config (found version "0.26") -- checking for module 'libusb-1.0' -- package 'libusb-1.0' not found -- Looking for libusb_handle_events_timeout_completed -- Looking for libusb_handle_events_timeout_completed - not found -- Looking for libusb_error_name -- Looking for libusb_error_name - not found -- libusb-1.0 not found. -- Looking for include file pthread.h -- Looking for include file pthread.h - found -- Looking for pthread_create in pthreads -- Looking for pthread_create in pthreads - not found -- Looking for pthread_create in pthread -- Looking for pthread_create in pthread - found -- Found Threads: TRUE CMake Error at CMakeLists.txt:69 (message): LibUSB 1.0 required to compile rtl-sdr -- Configuring incomplete, errors occurred!
Oh no dude! We're doomed!
Naw, it's cool, we can fix that by installing LibUSB, since that's what the last line of the error said to do.
$ apt-get install libusb Reading package lists... Done Building dependency tree Reading state information... Done E: Unable to locate package libusb
Oh no dude! We're doomed!
Naw, just kidding, we can fix that by looking for libusb-related packaged with aptitude:
$ aptitude search libusb p libusb++-0.1-4c2 - userspace C++ USB programming library p libusb++-dev - userspace C++ USB programming library development files i libusb-0.1-4 - userspace USB programming library i A libusb-1.0-0 - userspace USB programming library p libusb-1.0-0-dbg - userspace USB programming library development files p libusb-1.0-0-dev - userspace USB programming library development files p libusb-1.0-doc - documentation for userspace USB programming i A libusb-dev - userspace USB programming library development files [......]
We need both the regular and the development versions of LibUSB 1.0. So the package we need is: libusb-1.0-0-dev
apt-get install libusb-1.0-0-dev
Return to the SDR Project
Okay, now we can go back to our build directory in the rtll-sdr project, and re-run cmake:
$ cmake ../ -- Build type not specified: defaulting to release. -- Extracting version information from git describe... -- checking for module 'libusb-1.0' -- found libusb-1.0, version 1.0.17 -- Found libusb-1.0: /usr/include/libusb-1.0, /usr/lib/x86_64-linux-gnu/libusb-1.0.so -- Udev rules not being installed, install them with -DINSTALL_UDEV_RULES=ON -- Building with kernel driver detaching disabled, use -DDETACH_KERNEL_DRIVER=ON to enable -- Building for version: v0.5.3-12-ge3c0 / 0.5git -- Using install prefix: /usr/local -- Configuring done -- Generating done -- Build files have been written to: /root/codes/sdr/rtl-sdr/build
All done! Just kidding, you gotta make it first:
make Scanning dependencies of target convenience_static [ 5%] Building C object src/CMakeFiles/convenience_static.dir/convenience/convenience.c.o Linking C static library libconvenience_static.a [ 5%] Built target convenience_static Scanning dependencies of target rtlsdr_shared [ 10%] Building C object src/CMakeFiles/rtlsdr_shared.dir/librtlsdr.c.o [ 15%] Building C object src/CMakeFiles/rtlsdr_shared.dir/tuner_e4k.c.o [ 20%] Building C object src/CMakeFiles/rtlsdr_shared.dir/tuner_fc0012.c.o [ 25%] Building C object src/CMakeFiles/rtlsdr_shared.dir/tuner_fc0013.c.o [ 30%] Building C object src/CMakeFiles/rtlsdr_shared.dir/tuner_fc2580.c.o [ 35%] Building C object src/CMakeFiles/rtlsdr_shared.dir/tuner_r82xx.c.o Linking C shared library librtlsdr.so [ 35%] Built target rtlsdr_shared Scanning dependencies of target rtl_adsb [ 40%] Building C object src/CMakeFiles/rtl_adsb.dir/rtl_adsb.c.o Linking C executable rtl_adsb [ 40%] Built target rtl_adsb Scanning dependencies of target rtl_eeprom [ 45%] Building C object src/CMakeFiles/rtl_eeprom.dir/rtl_eeprom.c.o Linking C executable rtl_eeprom [ 45%] Built target rtl_eeprom Scanning dependencies of target rtl_fm [ 50%] Building C object src/CMakeFiles/rtl_fm.dir/rtl_fm.c.o Linking C executable rtl_fm [ 50%] Built target rtl_fm Scanning dependencies of target rtl_power [ 55%] Building C object src/CMakeFiles/rtl_power.dir/rtl_power.c.o Linking C executable rtl_power [ 55%] Built target rtl_power Scanning dependencies of target rtl_sdr [ 60%] Building C object src/CMakeFiles/rtl_sdr.dir/rtl_sdr.c.o Linking C executable rtl_sdr [ 60%] Built target rtl_sdr Scanning dependencies of target rtl_tcp [ 65%] Building C object src/CMakeFiles/rtl_tcp.dir/rtl_tcp.c.o Linking C executable rtl_tcp [ 65%] Built target rtl_tcp Scanning dependencies of target rtl_test [ 70%] Building C object src/CMakeFiles/rtl_test.dir/rtl_test.c.o Linking C executable rtl_test [ 70%] Built target rtl_test Scanning dependencies of target rtlsdr_static [ 75%] Building C object src/CMakeFiles/rtlsdr_static.dir/librtlsdr.c.o [ 80%] Building C object src/CMakeFiles/rtlsdr_static.dir/tuner_e4k.c.o [ 85%] Building C object src/CMakeFiles/rtlsdr_static.dir/tuner_fc0012.c.o [ 90%] Building C object src/CMakeFiles/rtlsdr_static.dir/tuner_fc0013.c.o [ 95%] Building C object src/CMakeFiles/rtlsdr_static.dir/tuner_fc2580.c.o [100%] Building C object src/CMakeFiles/rtlsdr_static.dir/tuner_r82xx.c.o Linking C static library librtlsdr.a [100%] Built target rtlsdr_static
Gnu Radio Baz
The Baz extension for gnu radio:
git clone https://github.com/balint256/gr-baz.git
and apparently I didn't install the right boost library.
Using RTL-SDR
Now that we've installed RTL-SDR, we can start to use it.
The Binary
You can enter the src/ directory of your Cmake build, and you'll see your rtl-sdr binary:
ls -1 src/ CMakeFiles cmake_install.cmake libconvenience_static.a librtlsdr.a librtlsdr.so librtlsdr.so.0 librtlsdr.so.0.5git Makefile rtl_adsb rtl_eeprom rtl_fm rtl_power rtl_sdr rtl_tcp rtl_test
Test
First thing I ran was the sdr_test binary:
./rtl_test Found 1 device(s): 0: Realtek, RTL2838UHIDIR, SN: 00000001 Using device 0: Generic RTL2832U OEM Kernel driver is active, or device is claimed by second instance of librtlsdr. In the first case, please either detach or blacklist the kernel module (dvb_usb_rtl28xxu), or enable automatic detaching at compile time. usb_claim_interface error -6 Failed to open rtlsdr device #0.
We can detach driver modules from the kernel by using rmmod, so we'll detach this module:
rmmod dvb_usb_rtl28xxu
and try again.
Hello RTL-SDR World!
$ ./rtl_test Found 1 device(s): 0: Realtek, RTL2838UHIDIR, SN: 00000001 Using device 0: Generic RTL2832U OEM Found Rafael Micro R820T tuner Supported gain values (29): 0.0 0.9 1.4 2.7 3.7 7.7 8.7 12.5 14.4 15.7 16.6 19.7 20.7 22.9 25.4 28.0 29.7 32.8 33.8 36.4 37.2 38.6 40.2 42.1 43.4 43.9 44.5 48.0 49.6 [R82XX] PLL not locked! Sampling at 2048000 S/s. Info: This tool will continuously read from the device, and report if samples get lost. If you observe no further output, everything is fine. Reading samples in async mode...
What does all this mean?!?
The antenna is basically ingesting raw radio frequency information, at whatever frequency it happens to be listening on (it's variable), and is reading 2048000 samples per second. That means, if we want to scan a whole range of frequencies, we can grab a handful of samples from each frequency, and loop through every single frequency, and it won't take very long. That enables us to create a "waterfall" display of activity across a whole range of frequencies, even though an antenna can only listen to one frequency at a time.
Dumping What You Hear
You can dump out what the antenna hears with the rtl_sdr script, which does a raw dump of binary data from onboard the SDR chip. This has a couple of nice parameters:
./rtl_sdr rtl_sdr, an I/Q recorder for RTL2832 based DVB-T receivers Usage: -f frequency_to_tune_to [Hz] [-s samplerate (default: 2048000 Hz)] [-d device_index (default: 0)] [-g gain (default: 0 for auto)] [-p ppm_error (default: 0)] [-b output_block_size (default: 16 * 16384)] [-n number of samples to read (default: 0, infinite)] [-S force sync output (default: async)] filename (a '-' dumps samples to stdout)
Suppose we want to listen to 900 MHz, like all the other cool hipster hacker kids who are doing HamProxy SDR projects. Okay, we're gonna listen to 920 MHz. We're reading at about 2 billion samples per second (take a minute to contemplate that: that's absolutely astounding). We can specify a number of samples, this obviously doesn't correspond to the number of samples it's taking per second because the two don't match up at all:
$ ./rtl_sdr /tmp/raw_sdr -f 920e6 -n 1e6
This will make a file full of gibberish:
Freeze. Kill. Respawn. Repeat.
If you run into problems with the radio freezing up or listening forever and not responding to Contrl+C, you can always do a killall on your process, unplug the USB dongle, re-plug it in, and run:
rmmod dvb_usb_rtl28xxu