
41-16 Time and Frequency
The difference between the two measurements is an estimate of Clock A – Clock B. Delays that
are common to both paths d
SA
and d
SB
cancel even if they are unknown, but uncorrected delay
differences between the two paths add uncertainty to the measurement result. Thus, the basic
eq
uation
fo
r
a CV
GPS
me
asurement
is
( ) ( ) ( ) ( )Clock A S Clock B S Clock A Clock B e e
SA SB
− − = − + −−
(4
1
.3)
e
co
mponents
th
at
ma
ke
up th
e
(e
SA
− e
SB
) error term include delay dierences between the two sites
caused by ionospheric and tropospheric delays, multipath signal reections, environmental conditions,
an
d
er
rors
in th
e
GP
S