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https://github.com/robotastic/led-dump1090

displays stuff on a LED matrix
https://github.com/robotastic/led-dump1090

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displays stuff on a LED matrix

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README 

        
Dump1090 README

===



Dump 1090 is a Mode S decoder specifically designed for RTLSDR devices.



The main features are:



* Robust decoding of weak messages, with mode1090 many users observed

  improved range compared to other popular decoders.

* Network support: TCP30003 stream (MSG5...), Raw packets, HTTP.

* Embedded HTTP server that displays the currently detected aircrafts on

  Google Map.

* Single bit errors correction using the 24 bit CRC.

* Ability to decode DF11, DF17 messages.

* Ability to decode DF formats like DF0, DF4, DF5, DF16, DF20 and DF21

  where the checksum is xored with the ICAO address by brute forcing the

  checksum field using recently seen ICAO addresses.

* Decode raw IQ samples from file (using --ifile command line switch).

* Interactive command-line-interfae mode where aircrafts currently detected

  are shown as a list refreshing as more data arrives.

* CPR coordinates decoding and track calculation from velocity.

* TCP server streaming and recceiving raw data to/from connected clients

  (using --net).



While from time to time I still add / fix stuff in my fork, I target

minimalism of the implementation. However there is a

[much more feature complete fork](https://github.com/MalcolmRobb/dump1090)

available, developed by MalcolmRobb.



Installation

---



Type "make".



Normal usage

---



To capture traffic directly from your RTL device and show the captured traffic

on standard output, just run the program without options at all:



    ./dump1090



To just output hexadecimal messages:



    ./dump1090 --raw



To run the program in interactive mode:



    ./dump1090 --interactive



To run the program in interactive mode, with networking support, and connect

with your browser to http://localhost:8080 to see live traffic:



    ./dump1090 --interactive --net



In iteractive mode it is possible to have a less information dense but more

"arcade style" output, where the screen is refreshed every second displaying

all the recently seen aircrafts with some additional information such as

altitude and flight number, extracted from the received Mode S packets.



Using files as source of data

---



To decode data from file, use:



    ./dump1090 --ifile /path/to/binfile



The binary file should be created using `rtl_sdr` like this (or with any other

program that is able to output 8-bit unsigned IQ samples at 2Mhz sample rate).



    rtl_sdr -f 1090000000 -s 2000000 -g 50 output.bin



In the example `rtl_sdr` a gain of 50 is used, simply you should use the highest

gain availabe for your tuner. This is not needed when calling Dump1090 itself

as it is able to select the highest gain supported automatically.



It is possible to feed the program with data via standard input using

the --ifile option with "-" as argument.



Additional options

---



Dump1090 can be called with other command line options to set a different

gain, frequency, and so forth. For a list of options use:



    ./dump1090 --help



Everything is not documented here should be obvious, and for most users calling

it without arguments at all is the best thing to do.



Reliability

---



By default Dump1090 tries to fix single bit errors using the checksum.

Basically the program will try to flip every bit of the message and check if

the checksum of the resulting message matches.



This is indeed able to fix errors and works reliably in my experience,

however if you are interested in very reliable data I suggest to use

the --no-fix command line switch in order to disable error fixing.



Performances and sensibility of detection

---



In my limited experience Dump1090 was able to decode a big number of messages

even in conditions where I encountered problems using other programs, however

no formal test was performed so I can't really claim that this program is

better or worse compared to other similar programs.



If you can capture traffic that Dump1090 is not able to decode properly, drop

me an email with a download link. I may try to improve the detection during

my free time (this is just an hobby project).



Network server features

---



By enabling the networking support with --net Dump1090 starts listening

for clients connections on port 30002 and 30001 (you can change both the

ports if you want, see --help output).



Port 30002

---



Connected clients are served with data ASAP as they arrive from the device

(or from file if --ifile is used) in the raw format similar to the following:



    *8D451E8B99019699C00B0A81F36E;



Every entry is separated by a simple newline (LF character, hex 0x0A).



Port 30001

---



Port 30001 is the raw input port, and can be used to feed Dump1090 with

data in the same format as specified above, with hex messages starting with

a `*` and ending with a `;` character.



So for instance if there is another remote Dump1090 instance collecting data

it is possible to sum the output to a local Dump1090 instance doing something

like this:



    nc remote-dump1090.example.net 30002 | nc localhost 30001



It is important to note that what is received via port 30001 is also

broadcasted to clients listening to port 30002.



In general everything received from port 30001 is handled exactly like the

normal traffic from RTL devices or from file when --ifile is used.



It is possible to use Dump1090 just as an hub using --ifile with /dev/zero

as argument as in the following example:



    ./dump1090 --net-only



Or alternatively to see what's happening on the screen:



    ./dump1090 --net-only --interactive



Then you can feed it from different data sources from the internet.



Port 30003

---



Connected clients are served with messages in SBS1 (BaseStation) format,

similar to:



    MSG,4,,,738065,,,,,,,,420,179,,,0,,0,0,0,0

    MSG,3,,,738065,,,,,,,35000,,,34.81609,34.07810,,,0,0,0,0



This can be used to feed data to various sharing sites without the need to use another decoder.



Antenna

---



Mode S messages are transmitted in the 1090 Mhz frequency. If you have a decent

antenna you'll be able to pick up signals from aircrafts pretty far from your

position, especially if you are outdoor and in a position with a good sky view.



You can easily build a very cheap antenna following the istructions at:



    http://antirez.com/news/46



With this trivial antenna I was able to pick up signals of aircrafts 200+ Km

away from me.



If you are interested in a more serious antenna check the following

resources:



* http://gnuradio.org/redmine/attachments/download/246/06-foster-adsb.pdf

* http://www.lll.lu/~edward/edward/adsb/antenna/ADSBantenna.html

* http://modesbeast.com/pix/adsb-ant-drawing.gif



Aggressive mode

---



With --aggressive it is possible to activate the *aggressive mode* that is a

modified version of the Mode S packet detection and decoding.

THe aggresive mode uses more CPU usually (especially if there are many planes

sending DF17 packets), but can detect a few more messages.



The algorithm in aggressive mode is modified in the following ways:



* Up to two demodulation errors are tolerated (adjacent entires in the magnitude

  vector with the same eight). Normally only messages without errors are

  checked.

* It tries to fix DF17 messages trying every two bits combination.



The use of aggressive mdoe is only advised in places where there is low traffic

in order to have a chance to capture some more messages.



Debug mode

---



The Debug mode is a visual help to improve the detection algorithm or to

understand why the program is not working for a given input.



In this mode messages are displayed in an ASCII-art style graphical

representation, where the individial magnitude bars sampled at 2Mhz are

displayed.



An index shows the sample number, where 0 is the sample where the first

Mode S peak was found. Some additional background noise is also added

before the first peak to provide some context.



To enable debug mode and check what combinations of packets you can

log, use `mode1090 --help` to obtain a list of available debug flags.



Debug mode includes an optional javascript output that is used to visualize

packets using a web browser, you can use the file debug.html under the

'tools' directory to load the generated frames.js file.



How this program works?

---



The code is very documented and written in order to be easy to understand.

For the diligent programmer with a Mode S specification on his hands it

should be trivial to understand how it works.



The algorithms I used were obtained basically looking at many messages

as displayed using a trow-away SDL program, and trying to model the algorithm

based on how the messages look graphically.



How to test the program?

---



If you have an RTLSDR device and you happen to be in an area where there

are aircrafts flying over your head, just run the program and check for signals.



However if you don't have an RTLSDR device, or if in your area the presence

of aircrafts is very limited, you may want to try the sample file distributed

with the Dump1090 distribution under the "testfiles" directory.



Just run it like this:



    ./dump1090 --ifile testfiles/modes1.bin



What is --strip mode?

---



It is just a simple filter that will get raw IQ 8 bit samples in input

and will output a file missing all the parts of the file where I and Q

are lower than the specified  for more than 32 samples.



Use it like this:



    cat big.bin | ./dump1090 --snip 25 > small.bin



I used it in order to create a small test file to include inside this

program source code distribution.



Contributing

---



Dump1090 was written during some free time during xmas 2012, it is an hobby

project so I'll be able to address issues and improve it only during

free time, however you are incouraged to send pull requests in order to

improve the program. A good starting point can be the TODO list included in

the source distribution.



Credits

---



Dump1090 was written by Salvatore Sanfilippo  and is

released under the BSD three clause license.