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+# 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
+