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diff --git a/writeup/article.md b/writeup/article.md new file mode 100644 index 0000000..c198ecf --- /dev/null +++ b/writeup/article.md @@ -0,0 +1,183 @@ +# RTLSDR usage + +# Index + + +1. Setup rtlsdr + 1.1. Get sources + 1.2. Drivers + 1.3. Check if works +2. Collection of tools + 2.1. FM + 2.2. Spectrum diagram + 2.3. ADSB + 2.4. AFSK1200 +3. Projects where rtlsdr used + 3.1. WebSDR +4. Problems + 4.1. Sync errors +5. Links +6. Changelog + + +## 1.Setup rtlsdr + + +By rtlsdr usually call RTL2832U chip based tv-tunners which +can be used for not just recievin DVB-T frequencies but much more +and yes price is ~$10 it mean that anyone can just buy and try +without "loosing" money. + + +### 1.1.Get sources + + +Main development repository is on http://sdr.osmocom.org/trac/wiki/rtl-sdr +on github you can find more repos with experminental +features (https://github.com/keenerd/rtl-sdr). + +Getting sources from git: +``` + git clone git://git.osmocom.org/rtl-sdr.git +``` +I prefer using plain binaries without any kind of installation. Just +compile and use binary without any troubles. +Build: +```bash + cmake . + make +``` +All binaries is in src dir + + +### 1.2.Drivers + + +Linux kernel have some drivers for rtlsdr stick and DVB-T. When you will plug +rtlsdr then kernel probably will load DVB-T drivers and you will not able +to use you rtlsdr for sdr. Way yo fix is it add some drivers to black list and +next time when you will plug rtlsdr this drivers will not be loaded. + +Check if rtlsdr related drivers is loaded: +```bash + lsmod | grep rtl28 +``` +If there is some drivers then balcklist driver by creating file +in */etc/modprobe.d/* with content: +``` + blacklist dvb_usb_rtl28xxu +``` +Next thing that could appear is permissions on rtlsdr usage when its pluged in. +To allow everyone to use create file in */etc/udev/rules.d/* with content: +``` + SUBSYSTEM=="usb", ATTRS{idVendor}=="0bda", ATTRS{idProduct}=="2838", \ + GROUP="adm", MODE="0666", SYMLINK+="rtl_sdr" +``` + +### 1.3.Check if works + +How to test if rtlsdr works? Run one of commands: + rtl_test + +I like to run rtl_adsb as you can see there that something is recieved and +you see that everything "works": + rtl_adsb + +There should be line by line showing up some "hex" lines. If some data is showen +then adsb data from plains is recieved. + +## 2.Collection of tools + + +### 2.1.FM + +Get some sound trancmited from FM radio stations. + +```bash + rtl_fm -f 96.3e6 -M wbfm -s 200000 -r 48000 - | aplay -r 48k -f S16_LE +``` + + +### 2.2.Spectrum diagram + +Scan spectrum to find some activities on different frequencies. +Good link with all description is http://kmkeen.com/rtl-power/ . +Main usage of rtl_power is : +```bash + rtl_power -f 76M:108M:125k -i 1 fm_stations.csv +``` +and then draw image : +```bash + heatmap.py fm_stations.csv fm_stations.png +``` + +### 2.3.ADSB + +ADS-B ( Automatic dependent surveillance broadcast ) in simple words airplain +geoposition, speed, height and flight number broadcasting. You can recieve +this data and see how many plains is around and sometimes flight number. + +rtlsdr have default one rtl_adsb programm but it shows only recieved data, +without any decoding. Here is dump1090 specifically for rtlsdr and nothing +more: + + https://github.com/antirez/dump1090 + +description howto install could be found also here + + http://www.satsignal.eu/raspberry-pi/dump1090.html + +Using in interactive mode with height in metrs: +```bash + dump1090 --interactive --metric +``` +Output: + +``` + Hex Flight Altitude Speed Lat Lon Track Messages Seen . + ------------------------------------------------------------------------------ + 71be01 10052 1009 36.434 33.544 45 9 1 sec + 424913 SDM6329 10966 711 36.440 33.405 221 65 0 sec +``` + + +### 2.4.AFSK1200 + +Gqrx is graphical SDR software where you can travel across frequencies +and in real time search for some transmission. + + http://gqrx.dk/ + +It have builtin AFSK1200 demodulator or in simple words ham radio packets. +And you could try to see what people sending in tex around the world. + +## 3.Projects where rtlsdr used + +### 3.1.WebSDR + +WebSDR probably best site where you can go and click on some radio reciever +and liste what happends in some particular country. WebSDR site contains +about 80 radio recievers around the world that can be accessed trought web +interface. + http://websdr.org/ + +If you whant setup your own radio reciever read FAQ, prepare mail and send mail +after that you could recieve precompiled websdr software with is easy +to setup with rtlsdr stick. + +## 4.Problems + +### 4.1.Sync errors + +Once there was sync error when was trying to use rtl_test or rtl_adsb. +To fix that changes for better quality usb cable. + +# 5.Links + +1. [http://kmkeen.com/rtl-demod-guide/](http://kmkeen.com/rtl-demod-guide/) +2. http://kmkeen.com/rtl-power/ +3. http://sdr.osmocom.org/trac/wiki/rtl-sdr +4. http://www.rtl-sdr.com/ +5. https://github.com/antirez/dump1090 +6. http://gqrx.dk + |