Time Synchronisation and Hardware Time Stamps - ethz-asl/mav_dji_ros_interface GitHub Wiki

1. What does the Time Sync Service (rosservice call ~/dji_sdk/sync_flag_control F_SYNC) do?

When you send a sync command (asking the flight controller to sync at some frequency F_SYNC), the timestamp packets you receive from the FC start sending you a software "clock pulse" - a sync byte that has value '1' at time intervals 1/F_SYNC and '0' at all other time instants. Sending the sync command also resets the free-running counter generating the timestamp.