User`s guide

Appendix
Motorola GPS Products - M12+ User's Guide Revision 6.X 09FEB05
201
A triple-difference measurement is the difference between a double difference at one
epoch of time and the same double difference at the previous epoch of time.
Differential GPS solutions can be computed using either code phase or carrier phase
measurements. In differential carrier phase solutions, the integer ambiguities must be
resolved.
Differential (Relative) Positioning
Determination of relative coordinates of two or more receivers that are simultaneously
tracking the same satellites. Dynamic differential positioning is a realtime technique
achieved by sending code corrections to the roving receiver from one or more monitor
stations. Static differential GPS involves determining baseline vectors between pairs of
receivers.
Dilution of Precision
A description of the geometrical contribution to the uncertainty in a position fix, given by
the expression DOP = SQRT TRACE (ATA), where A is the design matrix for the
instantaneous position solution (dependent on satellite receiver geometry). The type of
DOP factor depends on the parameters of the position fix solution. Standard terms for
GPS applications include the following:
GDOP Geometric DOP – three coordinates plus clock offset in the solution.
PDOP Position DOP – three coordinates.
HDOP Horizontal DOP - two horizontal coordinates.
VDOP Vertical DOP - height only.
TDOP Time DOP - clock offset only.
RDOP Relative DOP - normalized to 60 seconds
DoD
United States Department of Defense. The government agency that led the development,
deployment, and operation of GPS.
Doppler Aiding
The use of Doppler carrier phase measurements to smooth the code-phase
measurements. Also referred to as carrier aided smoothing or carrier-aided tracking.
Doppler Shift
The apparent change in frequency of a received signal due to the rate of change of the
range between the transmitter and receiver. See Reconstructed Carrier Phase.
Double-Difference Ambiguity Resolution
A method to determine the set of ambiguity values which minimizes the variance of the
solution for a receiver pair baseline vector.