Active marker deck

Active marker deck

Long distance and solid tracking

Compatible with Qualisys tracking systems and QTM

How it works

The Active marker deck  together with Qualisys QTM gives you long distance and solid tracking. Thanks to the 4 high-power LEDs you can set up to 4 different IDs giving you the possibility to uniqly identify a large number of rigid bodies, without the need of many reflective markers.

The hardware comes pre-programmed for Qualisys tracking systems, but can be re-programmed for other applications.



  • Using Qualisys QTM
  • Robust and long range tracking
  • Supports up to 4 different marker IDs
  • Generic mode (control intensity of each LED)
  • Move an LED by cutting an arm and wiring it instead.

Mechanical specifications

  • Weight: 3.1 g
  • Size (WxHxD): 75x75x5 mm
  • Designed for mounting above the Crazyflie product family

Electrical specification

  • STM32F031G6 MCU
  • Receiving IR LED (38kHz carrier)
  • 4 x high power IR LEDs (850 nm)
  • SWD connector (compatible with Debug adapter)
  • Compatible with Qualisys QTM V2019.3+


The Active Marker deck is mainly designed for Qualisys mocap systems and supports Qualisys Active markers, but it can also be used with other systems in a simplified mode. The deck has 4 arms with one IR LED on the tip of each arm and a light sensor in the center of the deck.

The deck is configured using the parameter sub system, for details on which parameter to use, see below.


The deck mode is set with the activeMarker.mode parameter.

Mode value comment
OFF 0 Always off
PWM 1 Always on, PWM modulated
MODULATED 2 Switching
QUALISYS 3 (default) Qualisys Active Marker mode

Off mode

All marker LEDs are turned off.

PWM mode

The marker LEDs are turned on and PWM modulated. The brightness of each LED is controlled by the marker parameters below, in the range 0 - 255.

Modulated mode

The LEDs are switched on and off at around 42 kHz (24 micro seconds cycle). The brightness of the LEDs during the “on” part of the cycle is controlled by the marker parameters below, in the range 0 - 255.

Qualisys mode

In this mode the LEDs act as Active markers with IDs that are identified by the Qualisys system and used for better 6-dof identification and tracking. The IDs are controlled by the marker parameters below. The Qualisys systems and the deck currently supports IDs in the range [0 - 170]

Marker parameters

Each marker is associated with a parameters that is used to set brightness or id. Please check out the parameter documentation for ‘activeMarker’



Getting started with expansion decks

If you have any further questions please contact