SDR-DVB
Ricezione del traffico aereo tramite radio SDR con il DVB-T RTL820T
Utilizzo di un'antenna efficace
Oltre alla corretta installazionee compilazione dei programmi, non dimenticatevi di avere una buona antenna! L'antenna fornita con il dongle ricevitore TV non è ottimizzata per la ricezione dei 1.09 GHz e quindi si avranno dei risultati migliori utolizzando un'antenna dedicata. Graham Leighton riporta degli ottimi risultati con la sua antenna autocostruita, consigliando i modelli Moonraker e DPD. Altre antenne autocostruite sono: collineare coassiale e collineare filare. Posizionate la vostra antenna il più in alto possibile e con un ampio spazio libero, idealmente all'aperto invece che in un luogo chiuso.
Il programma dump1090
Il programma dump1090 viene avviato e risiede nel Raspberry Pi, il quale può anche produrre diverse cartografie su un browser web, situato sulla tua rete locale (PC, Linux or Mac). Può essere utilizzato anche per verificare se il programma dump1090 sta funzionando correttamente e se il link TCP/IP è stato avviato sul tuo Raspberry Pi. Per fare ciò, digita semplicemente questo URL sul tuo browser:
http://<indirizzo-o-nome-del-Raspberry-Pi>:8080
dove l'indirizzo può ssere un numero o un nome, es.:
Preparare il Raspberry Pi
Please note I'm not any kind of RPi/Linux guru - my first contact with it was 6 days ago. If you have RPi/Linux questions, you'll probably need to ask someone else. In the lines below, can highlight the command required, use Ctrl-C or right-click Copy to get the text into the clipboard, and then if you use PuTTY you can right-click on the text area of the terminal session to enter the command into the Raspberry Pi. To use the software, do the following (tested on Linux 3.6.11 and NOOBS/Raspbian 3.12.22+).
[djt: If you need help with your Raspberry Pi and following the instructions below, please ask on the Plane Plotter Yahoo group. I am unable to answer direct e-mails about using the Raspberry Pi for ADB-S reception.]
I suggest you start with a new/clean SD Card. Download the latest NOOBS software (or Raspbian Wheezy OS), and follow the instructions on preparing the SD card here: http://www.raspberrypi.org/downloads Get your RPi working in it's simplest form so that it can connect to the internet via your home network. If you don't want to bother with a keyboard and display, you can run your RPi headless as described here. Please note that during some of the following commands you may be prompted for Yes or No answers, perhaps about the disk space which will be used by the new download. Unless specified otherwise here, simply accept the default answer, usually "Yes" (or "y"). Open a command prompt and type: sudo apt-get update This will update the table of updates to the latest revision. This may take some time to complete. Hint: you can use the Copy clipboard function in Windows to copy a command from this Web page, and then right-click your PuTTY screen to enter the command into the RPi session. Leave out the quotation marks when copying the text. It's an idea to check the Linux version at this point with a uname -a command. Initially, from a NOOBS install, mine was 3.6.11+, although on a second run, after an upgrade it was 3.10.23+, and after a third a day later it was 3.10.24+. Again at the command prompt type: sudo apt-get upgrade This will update the operating system to the latest version, and may therefore take "some time". Go and make a coffee! Note that upgrades after 2013-Dec-13 may overwrite the drivers required for the DVB-T USB stick. Please see here if this happens to you.
If, before any upgrade, your OS version shows as 3.6.11+ with the uname -a command I suggest leaving it without the upgrade.
Next, at the command prompt type: sudo apt-get install git-core This installs the git repository fetch code. You may already have this installed, in which case you will get a message advising that you already have the most up-to-date version. On the minimal Linux I started with "git" was not even present. Next, we will use the instructions to setup sdr-rtl which are given on this Web page. We stop where the text says "To run the rtl server type rtl_tcp -a and the IP address of your Pi". For your convenience, the instructions are copied below, and these are exactly what I typed into my Raspberry Pi. You don't need to follow the instructions on the quoted Web page as well as what's below. Step (9) below has been changed so that you no longer need the "sudo" commands to run the programs accessing the dongle.
sudo apt-get install git sudo apt-get install cmake sudo apt-get install libusb-1.0-0-dev # there is a slip on the referenced page sudo apt-get install build-essential
You can put all those commands onto one line should you wish (thanks to Sam Reed for pointing this out): sudo apt-get install git git-core cmake libusb-1.0-0-dev build-essential
although I prefer to do one command at a time in case there is an error, and you can see which step caused the problem.
Now install theRTL-2832U USB dongle driver source and compile: git clone git://git.osmocom.org/rtl-sdr.git cd rtl-sdr mkdir build cd build cmake ../ -DINSTALL_UDEV_RULES=ON make sudo make install sudo ldconfig
if it was successful you should see no return on the previous command. Install the RTL-2832U USB dongle on external powered USB HUB.
While many report using a powered USB hub, you may found the built-in ports adequate, if you have enough 5V power fed to the Raspberry Pi. You may get different results, and possibly if you use the live plug-and-play will more likely need the hub. I didn't need to plug and unplug the devices live, tested with a 1.5A supply, and intend to use a 2A supply from ModMyPi eventually. If you plug in the dongle directly to the RPi and it spontaneously reboots, don't be surprised! After an upgrade to 3.10 of Linux I also found that I needed a powered USB hub for correct working of the dongle.
sudo ldconfig
You should now do these steps to tell the system about what the new device is allowed to do, and reboot the system:
cd ~ sudo cp ./rtl-sdr/rtl-sdr.rules /etc/udev/rules.d/ sudo reboot rtl_test -t
The first time I tried this was with R802T tuner, and the test didn't work, saying it wanted an E4000 tuner. As I happened to have an E4000 device, I carried on using it. Further reading suggests that the test (-t) command is only intended to find the gap in the E4000 frequency coverage. I found no need for a reboot. Some issues may arise here: If you have used the more complex form of cmake in step 8.9 above when building rtl-sdr, you won't need the sudo prefix to run the dump1090 command in the future. But you will still need sudo for the other commands where shown, like apt-get. On versions of Raspian Linux later than 3.6.11, you may get an error message at this point: Found 1 device(s): 0: Generic RTL2832U Using device 0: Generic RTL2832U 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. This is because a DVB driver was added to the OS so that, er, TV could be received! This interferes with the operation of the DVB-T stick for ADS-B reception, so you need to take the steps outlined here before continuing. Re-run the test:
rtl_test -t
If you get error messages such as "cb transfer status: 1, canceling." it may be because the dongle is taking too much power from the Raspberry Pi. I've not seen this with all the dongles I've tested, so I was caught out the first time it happened. You may be able to resolved this problem by putting the USB dongle on a separately powered USB hub. I used this one as it was to hand, but it's not critical.
At this point, you might want to calibrate the dongle you are using to know what the frequency offset is. Usually, for ADS-B reception, the error which may be present is not critical. being up to 100 ppm (parts per million) which is a 100 KHz error at 1 GHz. However, for best results you should calibrate the dongle and use the measured offset to get best results. The easiest way to get a calibration is to use the kalibrate program, which I describe here. Now download the latest release dump1090 application source code. We will use the instructions from this Web page. We start following the instructions from about half way down the page where it says "git clone git://github.com/antirez/dump1090.git", which requires us to take these steps: cd /home/pi/ or cd ~ (goes to your home directory) git clone git://github.com/MalcolmRobb/dump1090.git cd dump1090 make [djt] I got errors at this point where pkg-config could not be found on my minimal Linux. Installing pkg-config cured this problem, but if you had no errors from the make step you will not need not need to do steps 5 and 6. sudo apt-get install pkg-config make When you type "./dump1090 --interactive", if you've got everything installed, compiled and connected correctly then you should see a screen displaying aircraft being received by your RPi. However, likely you will need to run this with privilege to allow the program to open the port. Note the double "--" if you are typing the command by hand, and note the "./" in front of the word "dump1090".
./dump1090 --interactive If you want to see the output over the network at this point, remember to add the "--net" command-line switch:
./dump1090 --interactive --net
There has been one report from Marco Haakmeester that the file rtl-sdr.h and dump1090.c require changes to compile properly, but Malcolm was unable to reproduce the problem. Contact Marco for more details if this affects you - I'll send his e-mail address on request.
Ricompilare dump1090
First stop any dump1090 process which is running. You can do this with the following commands, first checking whether you have a dump1090 process, and then killing it:
ps -e | grep dump1090 sudo killall dump1090 The ps -e shows all processes, ps alone would show just your processes. Here's what the end of the list from ps -e looks like on one RPi.
1870 tty5 00:00:00 getty 1871 tty6 00:00:00 getty 1980 ? 00:00:00 sudo 1981 ? 10:43:09 dump1090
13832 ? 00:00:02 kworker/0:0 14209 ? 00:00:13 kworker/u:2 Alternatively, if you have installed the automated start/stop script, below, enter:
sudo /etc/init.d/dump1090.sh stop Now follow these steps as you did before, with the additional step of moving (mv) the existing dump0190 directory to a safety copy, here named dump1090-001. For your next recompile when dump1090-001 will already exist, your might want to use dump1090-002, and so on. Note that if you are also running ppup1090 to send your output to Plane Plotter (and if you aren't, why not!), then you also need to copy the customised coaa.h which you have been sent to replace the newly downloaded file.
cd /home/pi/ mv dump1090 dump1090-001 git clone git://github.com/MalcolmRobb/dump1090.git cd dump1090 cp ../coaa.h . # if you are also running ppup1090 make Now you can start the program and logout. Use one of the two following commands according to your needs:
./dump1090 --quiet --net & ./dump1090 --quiet --net --net-ro-size 500 --net-ro-rate 5 & Just type logout after starting the program. Alternatively, if you have installed the automated start/stop script below, enter:
sudo /etc/init.d/dump1090.sh start
Pagina di riferimento: http://www.satsignal.eu/raspberry-pi/dump1090.html
