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novatel / novatel_oem7_driver

ROS Driver for NovAtel OEM7 GNSS/SPAN Receivers
https://wiki.ros.org/novatel_oem7_driver
MIT License
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Why does inspva under ROS use ros::time for timestamp even though my device is connected to GPS? #63

Closed leslieburke closed 1 year ago

leslieburke commented 1 year ago

If I change the system time to a wrong time, the time of the topic in ROS will also be wrong and will not be corrected by GPS.

novatel-applications-engineering commented 1 year ago

Hi @leslieburke, thank you for reaching out to us. We will work on reproducing this issue on our side and let engineering team know. We will update you once we learn more.

novatel-applications-engineering commented 1 year ago

Hi @leslieburke

Please be advised that generally ROS interacts with multiple sensors and systems, which are not necessarily connected to GNSS. Hence ROS doesn't have a notion of 'GPS time', only system time.

Nevertheless, UTC time can be calculated and logged in the rostopic /novatel/oem7/time

For more reference about the NovAtel Time logs, you can refer to: https://docs.novatel.com/OEM7/Content/Logs/TIME.htm

Another similar inquiry was posted on ROS answers: https://answers.ros.org/question/311325/properly-timestamping-gnss-data/