GJ - Privredna komora Srbije

NAS CQ 0 Q11 Q22 Q33
(22)
The CQ parameter is based on the standard deviation, but additionally, empirical assumptions about
environmental conditions are also taken into consideration. The CQ is derived so that here is at least two
thirds (2/3) of a probability that the computed position deviates from the true position by less than the CQ
value [3].
The second standard error
SAS 3
is defined by the cofactor matrix of preliminary measurements and a priori
variance of unit weight.
SAS 3
is calculated with the help of equations (7) and (20).
ACCURACY COMPARISON BETWEEN HOURLA AND DAILY OBSERVATIONS
During the comparison of hourly and daily observations the following data was taken into consideration:
• Adjusted coordinates of hourly observations Yizr , Xizr , H
izr
,
• Posteriori standard errors of hourly observations gained with procedures of adjustment
SAS 2
and
SAS3
,
• Coordinates Y, X , H of hourly observations,
• A priori standard errors of daily observations
NAS
and
SAS 3
.
Factor , which defines the values of boundary or maximal error, was also included in the comparison
procedure. The regarded values of during the comparison were 1, 2, 3 and 4 and they were used as a base
for the accuracy of hourly observations in the comparison with more accurate daily observations. When the
value of factor equals 3, the boundary or maximal error is given which is the same as the value of the
triple standard error. Considering this value it can be determined if the hourly observations in comparison
with more accurate daily observations peruse the classical theory of errors.
In the scope of the comparison the law of propagation of variances and covariances was used which states
that a sought quantity L is a function of measured values. This can be written as [5]:
L l1 l2 l3
l n
( , , ,..., )
(23)
Errors of every observation are transferred to the sought values L . For uncorrelated observations the variance
of the sough value can be defined by equation:
2 2
2 2 2
2
2
2
2
n
2
L l
...
1
l2 l3
ln
i
l i 1
1
l2 l3
l
n
li
(24)
The standard deviation of the sought value L :
n
L
i
i1
l i
2
(25)
314