An open source implementation of a receiver for the Digital Television standard ISDB-T (ARIB's STD-B31) in GNU Radio.
In particular, here in Uruguay we use the so-called "international" version, or ISDB-Tb (ABNT NBR 15601). However, the transmission scheme is exactly the same as in the original version, thus both references are equivalent.
We are in not-so-early (but still very active: we are starting to work on the transmitter side) development stages, and any help and/or feedback is still welcome. Since ISDB-T is similar to DVB-T, some of our blocks are heavily based on Bogdan Diaconescu's (BogdanDIA on git) DVB-T implementation (see https:/BogdanDIA/gr-dvbt).
Notes and examples
The receiver is now complete regarding operation. It is capable of demodulating the complete and 1-seg ISDB-T spectrum and its operation is such that a i5 PC is capable of showing the HD signal on-line. We foresee four modes of operation:
- Obtaining the transmission parameters. ISDB-T has several transmission parameters which may be selected by the transmitter and may (and probably will) change among channels and segments. Our current implementation is not yet capable of automatically changing its parameters, and it's up to the user to configure the receiver correctly. However, a simple example is provided (see examples/obtaining_parameters.grc) which may be used to obtain such parameters. Transmission mode and CP length should be tested until a clear peak is viewed (before using this flowgraph for the first time, open examples/sym_align_ofdm.grc, generate the code, open and close the companion). The TMCC decoder block should be configured to print the rest of the parameters.
- Vector Analyzer. See examples/viewing_the_constellation.grc on how to view the received complex symbols. The receiver has been tested with all three transmission modes (2k, 4k and 8k FFT) and several CP lengths.
- Complete decoding and displaying the video/audio. The receiver is capable of displaying on-line whole segments. If a 1-seg transmission is present, the example in examples/rx_1seg_demo.grc may be used to decode it (it has been tested with a RTL cheap SDR). Layer B is decoded in examples/rx_demo.grc. Note that the transmission's parameters should be set accordingly by using examples/obtaining_parameters.grc. The output of both flowgraphs is a Transport Stream file which may be played by ffplay or mplayer (for instance). If before executing the flowgraph we create the file as a pipe (mkfifo test_out.ts), it should display the video online.
- Signal analyzer. Our actual objective with the project is to develop a relatively inexpensive ISDB-T measurement equipment. In examples/fullseg_receiver_and_measurements.grc we present a flowgraph which measures several indicators, such as pre and post Viterbi BER, MER, channel frequency response, etc. In order to use it you should install our accompanying OOT module gr-mer (available at https:/git-artes/gr-mer).
For more information (papers, recordings of ISDB-T signals, etc.) please visit our webpage: http://iie.fing.edu.uy/investigacion/grupos/artes/gr-isdbt/.
Build instructions
For a system wide installation:
git clone https:/git-artes/gr-isdbt.git
cd gr-isdbt
mkdir build
cd build
cmake ../
make && sudo make install
For a user space installation, or GNU Radio installed in a location different from the default location /usr/local:
git clone https:/git-artes/gr-isdbt.git
cd gr-isdbt
mkdir build
cd build
cmake -DCMAKE_INSTALL_PREFIX=<your_GNURadio_install_dir> ../
cmake ../
make
make install
On Debian/Ubuntu based distributions, you may have to run:
sudo ldconfig
Remarks
-
Instructions above assume you have downloaded and compiled GNU Radio (either with the build-gnuradio script or with PyBOMBS). If you've used a pre-compiled binary package (like in $ sudo apt-get install gnuradio), then you should also install gnuradio-dev (and naturally cmake and git, if they were not installed, plus libboost-all-dev, libcppunit-dev, liblog4cpp5-dev and swig).
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The above build instructions are general. You may accelerate the compilation time by using the -j flag. Please visit http://www.math-linux.com/linux/tip-of-the-day/article/speedup-gnu-make-build-and-compilation-process for a guide.
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Note that gr-isdbt makes heavy use of VOLK. A profile should be run to make the best out of it. Please visit https://gnuradio.org/redmine/projects/gnuradio/wiki/Volk for instructions, or simply run:
volk_profile
FAQ
Q: Cmake complains about unmet requirements. What's the problem?
A: You should read the errors carefully (though we reckon they are sometimes mysterious). Most probably is a missing library. Candidates are Boost (in Ubuntu libboost-all-dev) or libcppunit (in Ubuntu libcppunit-dev).
Q: Cmake complains about some Policy CMP0026 and LOCATION target property and who knows what else. Again, what's the problem?
A: This is a problem with using Cmake with a version >= 3, which is installed in Ubuntu 16, for instance. The good news is that you may ignore all these warnings.
Q: It is not compiling. What's the problem?
A: Again, you should read carefully the errors. Again, it's most probably a missing library, for instance log4cpp (in Ubuntu liblog4cpp5-dev). If the problem is with the API of GNU Radio, you should update it.
Q: I got the following error: "AttributeError: 'module' object has no attribute 'viterbi_decoder'" (or some other block). Why?
A: This problem may be generated by several factors. Did you "sudo ldconfig"? Do you have PYTHONPATH set? (It should include at least /usr/local/lib/python2.7/dist-packages). Another possibility is that you don't have swig installed (in this case, you must uninstall gr-isdbt, delete CMakeCache.txt in the build directory, and re-install; that is, after installing swig).
Q: Video is not playing. Why?
A: In our experience, the best player is ffplay, which comes along ffmpeg. You should try it.
IIE Instituto de Ingeniería Eléctrica
Facultad de Ingeniería
Universidad de la República
Montevideo, Uruguay
http://iie.fing.edu.uy/investigacion/grupos/artes/
Please refer to the LICENSE file for contact information and further credits.