FAQ

Frequently asked questions.

What data does DeskRadar use?

DeskRadar reads a local dump1090-style JSON feed from http://127.0.0.1:8080/data/aircraft.json by default. It does not draw every object in that feed, only those with enough data to draw and that are in range

Why HTTP?

HTTP keeps DeskRadar flexible for people who already have an ADS-B receiver running in their house. Instead of requiring the whole receiver stack to live inside the enclosure, DeskRadar can read an existing dump1090-style feed over the network and send simple draw requests to the MatrixPortal. That makes it easier to buy or build just the matrix and enclosure side of the project and display data you already have.

Do I need internet access?

Not for the core display loop. The Pi needs local network connectivity to the MatrixPortal and local access to dump1090. Internet access is useful for installing packages, updates, and anything else your Pi image or receiver setup needs.

Why are some aircraft missing?

The app filters out aircraft without the required fields, aircraft below MIN_ALT, aircraft outside the configured latitude/longitude bounds, and aircraft whose receiver data has no usable position. ADS-B reception is also line-of-sight, so antenna placement matters.

Why is the MatrixPortal showing "Waiting..."?

That means the MatrixPortal has joined WiFi and started its HTTP server, but it has not received draw data yet. Check that the Pi can resolve deskradar-portal.local, that MATRIX_HTTP_URL in /etc/deskradar/config.json points to the MatrixPortal IP, and that deskradar.service is running.

Why does the MatrixPortal reboot?

The firmware intentionally reboots if WiFi disconnects or if no HTTP request arrives for 60 seconds. The main app sends /draw when pixels change, /no-change when they do not, and /empty when there are no aircraft in the store.

What should be in MatrixPortal wifi.txt?

Exactly two lines: SSID on line 1 and password on line 2. The default file contains the Pi AP credentials. When moving to LAN, update it to the same WiFi network as the Pi. See Moving to LAN.

Can I use Ethernet for the Pi?

The MatrixPortal still needs WiFi. The Pi can use Ethernet as long as it can reach the MatrixPortal over the same LAN and resolve or otherwise address deskradar-portal.local. The current configurator's WiFi switching flow is built around wlan0 and NetworkManager.

Why does closest aircraft highlighting not appear with one aircraft?

The LCD can show the closest aircraft when one is present. The matrix highlight code only recolors a closest aircraft when SHOW_CLOSEST is enabled and more than one aircraft is in the store.

How do I change the displayed range?

Edit DISPLAY_RADIUS_NM in the web configurator or in /etc/deskradar/config.json. The value is the radius in nautical miles around LAT/LON. Restart deskradar after manual config edits.

What is the 2x2 grey dot in the middle?

The MatrixPortal firmware always redraws four constant centre pixels at (31,31), (31,32), (32,31), and (32,32). These mark the display centre.