Sources of data¶

jet1090 decodes feeds of Mode S messages coming from a variety of sources.

RTL-SDR dongles¶

The most common source is the RTL-SDR dongle.

rtl-sdr dongle

jet1090 must be compiled with the rtlsdr feature in order to support RTL-SDR dongles.

You can check whether jet1090 detects your dongle:

$ jet1090 --discover=rtlsdr
Detached kernel driver
Found Rafael Micro R820T tuner
Reattached kernel driver
[INFO] Opening Generic RTL2832U OEM :: 00000001...
Detached kernel driver
Found Rafael Micro R820T tuner
Reattached kernel driver

You can then start decoding incoming messages. Use the --verbose option to check it is working well.

$ jet1090 --verbose rtlsdr://
Found Rafael Micro R820T tuner
[INFO] Opening Generic RTL2832U OEM :: 00000001...
Found Rafael Micro R820T tuner
[INFO] Using format CS16.
Allocating 15 zero-copy buffers

{"timestamp":1735082050.8826132,"frame":"8d34768d58b524b5986843dfee26","df":"17","icao24":"34768d","bds":"05","tc":11,"NUCp":7,"NICb":0,"altitude":35050,"source":"barometric","parity":"odd","lat_cpr":23244,"lon_cpr":26691,"metadata":[{"system_timestamp":1735082050.8826132,"rssi":-28.450745,"serial":14924845721654670821,"name":"rtlsdr"}]}
{"timestamp":1735082051.040175,"frame":"8d34768de11200000000002919db","df":"17","icao24":"34768d","bds":"61","subtype":"emergency_priority","emergency_state":"none","squawk":"2010","metadata":[{"system_timestamp":1735082051.040175,"rssi":-29.93521,"serial":14924845721654670821,"name":"rtlsdr"}]}

Tip

It is recommended to specify a reference location in order to decode ground messages as well.

You may use four-letter airport codes, three-letter airport codes, or latitude and longitude values separated by a comma.

jet1090 --verbose rtlsdr://@EHAM  # Amsterdam Schiphol airport (NL)
jet1090 --verbose rtlsdr://@LHR  # London Heathrow airport (UK)

Tip

By default, all dongles seem to have the same serial number 00000001.

If you want to give a different serial number to one of them, you may use the rtl_eeprom program:

rtl_eeprom -d 0 -s 00000002

If you have several dongles attached to different antennas, you may specify which one to select based on their serial number. That information will appear in the "name" field in the metadata:

jet1090 rtlsdr://serial=00000001 rtlsdr://serial=00000002

Beast format¶

TCP¶

Most decoders share the data they decode in the Beast binary format which contains timestamp information, signal level information (rssi) and Mode S short or long messages.

dump1090 sends the data from the 30005 port;
Radarcape and Air!Squitter receivers (by jetvision) send their CRC pre-checked raw data from the 10003 port.

You can decode that data with the following command:

jet1090 --verbose tcp://192.168.0.20:10003

You can add more receivers to the command:

jet1090 --verbose tcp://192.168.0.20:10003@LFBO tcp://192.168.0.30:10003@LFPO

UDP¶

When receivers are not accessible by the client for network configuration reasons, it is common practice to redirect the Beast feed to a UDP endpoint on another IP address. There is a dedicated setting on Radarcape devices for that. Otherwise, you can use socat to redirect the TCP output to an external UDP endpoint:

socat TCP:localhost:30005 UDP-DATAGRAM:1.2.3.4:5678

You can run jet1090 on that remote machine:

jet1090 --verbose udp://:5678

Warning

In UDP, only one program can listen to a specific port at a time. If you need multiple instances of a program to receive the same data feed, you can use the following WebSocket solution with tools like wsbroad and websocat.

WebSocket¶

The following settings helps to centralize several UDP feeds on one machine, and redistribute them.

First run the wsbroad command:

wsbroad 0.0.0.0:9876

Then redirect the UDP feed to a WebSocket endpoint:

websocat -b -u udp-l:127.0.0.1:5678 ws://0.0.0.0:9876/5678

You may then check data is coming:

websocat ws://localhost:9876/5678

Tip

You may create some services for managing these connexions more easily. Copy the service files to .config/systemd/user then:

systemctl --user start wsbroad
systemctl --user start websocat@5678

You can have a websocat@.service file as such:

[Unit]
Description=Redirect UDP %i streaming to WebSocket

[Service]
Type=simple
ExecStart=/home/user/.local/bin/websocat -b -u udp-l:0.0.0.0:%i ws://0.0.0.0:9876/%i
RestartSec=3

[Install]
WantedBy=multi-user.target

and a wsbroad.service as:

[Unit]
Description=WebSocket broadcast at 9876

[Service]
Type=simple
ExecStart=/home/user/.local/bin/wsbroad 0.0.0.0:9876
Restart=always
RestartSec=3

[Install]
WantedBy=multi-user.target

SeRo Systems API¶

If you have a token for the SeRo Systems API, include it in your configuration file with the sero.token entry.