Invalid or erroneous data like -20000000 in navsatfix messages

[ayoubasritii]

Hello,

I am using the Septentrio INS SBI Pro + and the official driver for my project, I have encountered an issue where the navsatfix topic occasionally publishes invalid values, specifically -20000000, under certain conditions (e.g., bad GNSS signal). This behavior can lead to complications in downstream applications such as localization and navigation systems.

Description of the issue:

• The navsatfix messages from the driver sometimes contain latitude and longitude values of -20000000.
• The status field of the navsatfix message during these instances is -1.

Impact:

• These invalid values can disrupt the performance of localization systems that rely on accurate GPS data.
• Filtering these values externally is a workaround but not an ideal solution, as it adds complexity and potential points of failure in the system.

Expected behavior:

• It would be preferable for the driver to not publish navsatfix messages under these conditions.

Environment:

• ROS Version: noetic
• Septentrio Driver Version: 1.3.2 (2023-11-19)
• Hardware/Platform: Ubuntu 20.04

I am looking forward to any suggestions, guidance, or fixes you can provide. Additionally, if there's any further information or testing I can assist with, please let me know.

Best regards, Ayoub.

[thomasemter]

Hello Ayoub,

the driver works as intended and correctly flags the fix status as STATUS_NO_FIX. This behavior allows for the system to distinguish between a communication failure from the receiver and invalid data.

In order to process the data, it is a must to always evaluate the status flag. Nonetheless, we are contemplating about changing invalid data to NaN to make it more obvious.

Best regards, Thomas

[ayoubasritii]

Hello Thomas, Thank you for your prompt reply. I agree that the status flag should be evaluated, but according to this workshop the driver should be able to be used by the robot localization package. As far as I know, this package does not handle invalid or NaN data or am I mistaken?

[thomasemter]

robot_localization does check for good_gps, i.e., for both valid status and not NaN.