DOP is the abbreviation of Dilution of Precision, which is literally translated as "precision intensity" and usually translated as "precision factor".

Accuracy factor: describes the influence of satellite geometric factors on fixed-point accuracy, and points out the geometric strength of the tracked satellite during measurement. Including:

GDOP (Geometrical): It includes longitude, latitude, elevation, time and other factors, and is called geometric precision factor.

PDOP: It includes longitude, latitude, elevation and other factors, and is called three-dimensional (spatial) position accuracy factor.

HDOP (horizontal): It includes factors such as latitude and longitude, and is called horizontal (plane) position accuracy factor.

VDOP (vertical): Only the elevation factor is included, which is called the elevation accuracy factor.

TDOP (time): the geometric precision factor of clock difference.