Spectra Precision ProMark 800 Reference Manual - Manual (Page 78)

66
Precise Surveying - Field Applications & Concepts
From this interpolation the system can derive elevation from
ellipsoidal height using the following formula:
Elevation [1] = Ellipsoidal Height - Interpolated geoidal separation
General Considerations Regarding Accuracy
What Accuracy
Mainly Depends On
In precise surveying, accuracy is primarily tied to the capacity
of a system to detect the finest variation in the portion of
carrier wavelength arriving at the surveyed point, assuming
the number of complete carrier cycles has been determined
successfully (cf. integer ambiguity in Initialization on page
49).
Knowing that the carrier wavelength of the L1 signal used in
the processing is equal to 19 cm, this gives an idea of the
processing step the system has to go through to achieve
centimeter accuracy.
In practice, accuracy will first depend on the following
parameters:
• Quality of the carrier phase measurements, i.e. quality of
the receiver (noise level) and environmental conditions
(number of received satellites, presence or absence of
multipaths).
• Intrinsic quality of the processing algorithms used.
Reference
Ellipsoid
Surveyed Point
Geoid
To center of ellipsoid
[1]
[1]: Elevation (above geoid)
[2]: Interpolated geoidal separation
[2]
Satellite
Full carrier wavelength (19
cm)
Fraction of carrier wa
velength
Rover