Analysis of DOP and its preciseness in GNSS position estimation

Accurate positioning of objects is important for navigation applications which gives rise to many interesting and challenging mathematical problems. These problems involve the relationship between positioning accuracy and satellite geometry in accordance to the user's position. Dilution of precision is an indicator of satellite geometry for constellation of satellites used to determine a position. Better the geometry, better the position accuracy. DOP describes the geometric strength of the visible satellites configuration on the GPS accuracy. Ideally, the visible satellites should be located at wide angles relative to each other. The geometry of such satellite configuration is said to be strong and the DOP values are low.GPS signals from small region of sky gives larger DOP values, and position accuracy will suffer. If we accept lower elevation mask angle, several more satellites are available and DOP values drop to about its ideal value. The main motivation for this work is to introduce with the concept of DOPs: GDOP, PDOP, HDOP, VDOP, TDOP and to derive a comparative conclusion on DOP among GPS, Galileo and combined GPS - Galileo satellite configuration.