Data Logs
Chapter 6
EuroPak-15a Receiver User Manual Rev 5
77
6.3.3
CLOCKMODEL
Current Clock Model Status
The
CLOCKMODEL
log contains the current clock-model status of the receiver.
Monitoring the
CLOCKMODEL
log will allow you to determine the error in your receiver reference oscillator
as compared to the GPS satellite reference.
All logs report GPS time not corrected for local receiver clock error. To derive the closest GPS time, subtract
the clock offset from the GPS time reported. The clock offset can be calculated by dividing the value of the
range bias given in field
6
of the CLOCKMODEL log by the speed of light (
c
).
The following symbols are used throughout this section:
B =
Range bias (m)
BR =
Range bias rate (m/s)
SAB = Gauss-Markov process representing range bias error due to SA clock dither (m)
The standard clock model now used is as follows:
clock parameters array
= [ B BR SAB]
covariance matrix
=
σ
2
B
σ
B
σ
BR
σ
B
σ
SAB
σ
BR
σ
B
σ
BR
2
σ
BR
σ
SAB
σ
SAB
σ
B
σ
SAB
σ
BR
σ
SAB
2
