OpenRadar: Transponder

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FGFS introduces a generic transponder very soon. It will be available via Radio Settings (F12) in all planes. The devices in the cockpit will be adapted and build in soon(at least I hope that).

This allows us to reach a new level of realism, even though, many don't complain that we don't have to use it yet. Using this new level of realism will be optional, if you fly by your own or if the ATC of the controlled airspace does not ask for it.

In short, a transponder transmits a four digit number, each from 0 to 7. It allows the ATC to identify your radar echo with your aircraft and flight. Additional there are reserved numbers that allow to transmit additional information like uncontrolled VFR flight, emergency or radio failure. There are different modes and features. But in short: Some transmitter send the altitude of the aircraft to the ATC, some do not.

Current implementation in Open Radar

OpenRadar will support these new possibilities, by still supporting the plain and easy traditional mode.

The current implementation is a prototype, and will be improved. There is simply a lack of exact definitions. So I decided, to prepare a prototype and let you users try and discuss it.

The data block layouts

The new OpenRadar version allows to set the aircraft symbol and data block text depending on the available data.

There are 'modes' that allow to have different implementations available at the same time, and switch between them.

In the map menu (new) there is a new possibility to set the data block layout.

You can choose between:

Mode Transponder support Description
Traditional No Like you know it, plus a new line for the aircraft model.
Simulation Yes More like VLC for instance: callsign, ICAO aircraft code, altitude in 3 digits, ground speed in 2 digits.
Pure Simulation Yes Like Simulation, but contacts with disabled / unavailable transmitters are displayed as pure dots, without data.

The symbols in Simulation and Pure Simulation mode

Symbol Description
Filled diamond ♦ Transponder offline or standby. No squawk code transmitted.
Asterix * Uncontrolled contact.
Empty square Uncontrolled contact squawking VFR
Letter Controlled contact. Letter indicates controlling ATC. (to be implemented)

Assigning and revoking squawks

If you should meet a contact with built in transponder (FGFS Git version), you may enable the simulation mode.

This will display two new menu items above the flight strips: Assign Squawk: A right click on it will open a small dialog to define your range. Currently I do not import POF files, that does not mean I never will. For now, agree with ATC in range separate ranges and define them here. Each left click on the menu item will assign the next free number out of your range to the selected contact. With the click the appropriate message is send via chat. The contact is displayed in a different color until he has tuned in the assigned code.

Revoke Squawk: If you need to revoke the assigned squawk code (the contact continues to fly uncontrolled VFR), select the contact and click on the second new menu item. The squawk code is freed for re-use, once, the contact has changed the transponder code away.

Aircaft codes via Model names

There are discussions about what to display: The model name, transmitted by FGFS or the ICAO aircraft code. Currently, the traditional mode shows the model, the simulation mode the ICAO codes, if they are known already.

Model name

  • ATC knows better, which aircraft is used
  • ATC might help with aircraft specific knowledge
  • Longer
  • Used every where else in the FGFS world (MP Map)

ICAO code

  • Closer to reality
  • Harder to understand/recognize
  • Shorter (more space for other information)

What we will use finally, depends on what we agree. We should avoid that OpenRadar builds its own universe....

Flight strips

It is planned to rework the flight strips technically to be more flexible. Up to now, there is only one change:

On the first line at the right side, OpenRadar displays the squawk codes if the aircraft transmits a code:

'1234' means the contact sends the assigned squawk code 1234, or there is no assigned code, but the contact squawks 1234.

'1234 (5678)' The contact got 1234 assigned but transmits 5678.

Related content

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