# Revision history [back]

Note that /gps/fix includes GPS points (decimal degree format) which are both the single point precision(SPP) points as well as the RTK corrected points. I had to modify the gps driver so that the status information reflects the message type (SPP/RTK). Does the navsat_transform_node take into consideration whether the point is augmented or not? Does it need to?

So /gps/fix is one topic that is outputting a sensor_msgs/NavSatFix message, correct? I'm not quite following what you mean here; can you post a sample message? What did you modify in your driver, and how is that reflected in the message?

From what I understand, a single SPP GPS and a single IMU can work but may not be very accurate. How would I go about including the RTK position information? Should I set the datum to the base station position or would that mess up the global coordinates?

If the RTK data is outputting a world-frame pose as a nav_msgs/Odometry message, I would advise that you not bother with the /gps/fix data or navsat_transform_node. If you want to include the IMU data, I would just fuse the odometry and IMU data as inputs to a single instance of the filter.

Note that /gps/fix includes GPS points (decimal degree format) which are both the single point precision(SPP) points as well as the RTK corrected points. I had to modify the gps driver so that the status information reflects the message type (SPP/RTK). Does the navsat_transform_node take into consideration whether the point is augmented or not? Does it need to?

So /gps/fix is one topic that is outputting a sensor_msgs/NavSatFix message, correct? I'm not quite following what you mean here; can you post a sample message? What did you modify in your driver, and how is that reflected in the message?

From what I understand, a single SPP GPS and a single IMU can work but may not be very accurate. How would I go about including the RTK position information? Should I set the datum to the base station position or would that mess up the global coordinates?

If the RTK data is outputting a world-frame pose as a nav_msgs/Odometry message, I would advise that you not bother with the /gps/fix data or navsat_transform_node. If you want to include the IMU data, I would just fuse the /gps/rtkfix odometry and IMU data as inputs to a single instance of the filter.

Note that /gps/fix includes GPS points (decimal degree format) which are both the single point precision(SPP) points as well as the RTK corrected points. I had to modify the gps driver so that the status information reflects the message type (SPP/RTK). Does the navsat_transform_node take into consideration whether the point is augmented or not? Does it need to?

So /gps/fix is one topic that is outputting a sensor_msgs/NavSatFix message, correct? I'm not quite following what you mean here; can you post a sample message? What did you modify in your driver, and how is that reflected in the message?

From what I understand, a single SPP GPS and a single IMU can work but may not be very accurate. How would I go about including the RTK position information? Should I set the datum to the base station position or would that mess up the global coordinates?

If the RTK data is outputting a world-frame pose as a nav_msgs/Odometry message, I would advise that you not bother with the /gps/fix data or navsat_transform_node. If you want to include the IMU data, I would just fuse the /gps/rtkfix odometry and IMU data as inputs to a single instance of the filter.

2. Your link0_broadcaster static transform broadcaster make sense, as you can replace the first-tier EKF that way (note that you could also just run the EKF and everything else in the odom frame, but this works too). However, I am concerned about the second static transform, link1_broadcaster. You have defined it from map->gps, but your GPS isn't located at (0, 0) in the map frame. It's affixed to your robot. The transform should go from base_link-gps.