How to use PTP sync with an external clock master (Camera Sync Unit)

The Camera Sync Unit (CSU) can be used with any Qualisys camera system and configured to synchronize with an external clock master using the standard PTP protocol.

The use of PTP sync with an external clock master requires that the cameras are configured for it. Previously, this was done through the Advanced settings of the Qualisys Firmware installer (QFI). However, for QTM 2025.2 Update 3 and higher, setting the PTP mode can no longer be done via QFI, but requires the use of a camera configuration tool. For more information, contact Qualisys support.

Connecting to an external clock master

The external clock master should be connected to the same Local Area Network as the cameras. The following requirements apply to the external clock master:

  • Standard: IEEE 1588:2008 (PTPv2)
  • ipv4/udp
  • Delay mechanism: End-to-End (E2E)
  • Two-step clock
  • Sync message interval: 1s

For adding the timestamp to the motion capture frames, activate the timestamp option on the Synchronization page under Project Options and set the type to Camera time, see chapter Timestamp.

Oqus systems can use PTP sync without a Camera Sync unit, but it requires extra configuration, see chapter How to use PTP sync with an external clock master (Oqus).