Relationship between accuracy factor (DOP) and covariance in GPS data (reference link)

GPS Accuracy factor in data (DOP) And covariance
Reference link ：
[1] evenator. libnmea_navsat_driver/driver.py [EB/OL]. https://github.com/ros-drivers/nmea_navsat_driver/blob/master/src/libnmea_navsat_driver/driver.py , 2021-11-25/2022-06-29.
[2] itzmejawad. HDOP and VDOP in mavros? #1656. [EB/OL]. https://github.com/mavlink/mavros/issues/1656, 2021-11-25/2022-06-29.
[3] https://github.com/mavlink/mavros/blob/c121f6bde0b47bc031bf92a9a746bac4970944c7/mavros/src/plugins/global_position.cpp#L180-L193
[4] Yang Xi . GPS Positioning notes 2 ( Positioning accuracy and DOP) [EB/OL]. https://zhuanlan.zhihu.com/p/110085139, 2020-03-01/2022-06-29.