File : ITRF94CLA
CLASSIFICATION OF THE COORDINATES FOR ITRF94
In the analysis performed for ITRF94, a coordinate was estimated for each
point at the epoch 1993.0 as well as a velocity. We choose to adopt the
reliability as the main criterium, and specifically classified the points
using the quality number QN(T) which is defined by:
A set of points for a site have a QN(T) of n if they are linked by local
surveys and
- each has at least one space derived position (R, L, M, P or D)
at epoch T with a maximum residual (over the three components) below n
centimeters
- there are at least two different techniques in the previous sets of
points
- the local surveys for all these points have also a maximum residual below
n centimeters
This means that at least two independent techniques agree to better than n
centimeters for these points.
Using this QN, we have defined the four classes:
A: points with QN(93) and QN(88) better than 2 centimeters
B: points not in A but with QN(93) better than 3 centimeters
C: point not included in A or B with no large residual
Z: point with large residual:blunder or poor determination