PDOP or GDOP

I would like to know in general which one is typically chosen to
indicate the quality of DOP and GPS accuracy, PDOP or GDOP?

Johnson wrote:

http://www.Colorado.EDU/geography/gcraft/notes/gps/gps_f.html


PDOP = Position Dilution of Precision (3-D), sometimes the Spherical DOP.
HDOP = Horizontal Dilution of Precision (Latitude, Longitude).
VDOP = Vertical Dilution of Precision (Height).
TDOP = Time Dilution of Precision (Time).

I use PDOP and HDOP

Amd it is probably worth mentioning the GDOP is a term that refers to all of
these--they are all geometry only estimates of relative precison.. So the
choice is never between PDOP and GDOP ) as in the orignal post question) as
PDOP is "one of the kinds of GDOP". (The webpage calls the above
"components" of GDOP but they are not components in the usual sense.)

On Wed, 13 May 2009 23:23:04 GMT, "David L. Wilson"

Avoid NOJOP = Dilution of the economy (Money).

ate
DOP.
of
the
as

You can think of DOP along each coordinate axis, so that in a North-
East-Down reference frame there is a North DOP, an East DOP as well as
the vertical DOP.
HDOP =3D sqrt( northDop^2 + eastDOP^2)
PDOP =3D sqrt(HDOP^2 + VDOP^2)
Finally, GDOP =3D sqrt(PDOP^2 + TDOP^2)
So, use PDOP if you are interested in your receiver's position
dilution of precision, use GDOP if you are interested in accounting
for the Time dilution of precision as well. In my experience, most
people use PDOP or TDOP, but rarely GDOP.