Novatel OM-20000041 用户手册
D
Logs summary
MiLLennium GPSCard Software Version 4.50 Command Descriptions Manual Rev 1
147
CLKA/B
Receiver Clock Offset Data
This record is used to monitor the state of the receiver time. Its value will depend on the
CLOCKADJUST
command.
If
CLOCKADJUST
is enabled, then the offset and drift times will approach zero. If not enabled, then the offset will
grow at the oscillator drift rate. Disabling
CLOCKADJUST
and monitoring the
CLKA
/
B
log will allow you to
determine the error in your GPSCard 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 one must subtract
the clock offset shown in the
CLKA
log (field 4) from
GPS
time reported.
The internal units of the new clock model’s three states (offset, drift and GM state) are meters, meters per second,
and meters. When scaled to time units for the output log, these become seconds, seconds per second, and seconds,
respectively. Note that the old units of the third clock state (drift rate) are seconds per second per second.
and meters. When scaled to time units for the output log, these become seconds, seconds per second, and seconds,
respectively. Note that the old units of the third clock state (drift rate) are seconds per second per second.
CLKA
Structure:
Example
$CLKA,841,499296.00,9.521895494E-008,-2.69065747E-008,2.061788299E-006,
9.642598169E-008,8.685638908E-010,0*4F
$CLKA
week
seconds
offset
drift
SA G-M state
offset std
drift std
cm status
*xx
[CR][LF]
Field #
Field type
Data Description
Example
1
$CLKA
Log header
$CLKA
2
week
GPS week number
637
3
seconds
GPS seconds into the week
511323.00
4
offset
Receiver clock offset, in seconds. A positive offset implies that the
receiver clock is ahead of GPS Time. To derive GPS time, use the
following formula:
receiver clock is ahead of GPS Time. To derive GPS time, use the
following formula:
GPS time = receiver time - (offset)
-4.628358547E-003
5
drift
Receiver clock drift, in seconds per second. A positive drift implies that
the receiver clock is running faster than GPS Time.
the receiver clock is running faster than GPS Time.
-2.239751396E-007
6
SA G-M state
This field contains the output value of the Gauss-Markov Selective
Availability clock dither estimator, in units of seconds. The value reflects
both the collective SA-induced short-term drift of the satellite clocks as
well as any range bias discontinuities that would normally affect the clock
model’s offset and drift states.
Availability clock dither estimator, in units of seconds. The value reflects
both the collective SA-induced short-term drift of the satellite clocks as
well as any range bias discontinuities that would normally affect the clock
model’s offset and drift states.
2.061788299E-006
7
offset std
Standard deviation of receiver clock offset, in seconds
5.369997167E-008
8
drift std
Standard deviation of receiver drift, in seconds per second
4.449097711E-009
9
cm status
Receiver Clock Model Status where 0 is valid and values from -20 to -1
imply that the model is in the process of stabilization
imply that the model is in the process of stabilization
0
10
*xx
Checksum
*7F
11
[CR][LF]
Sentence terminator
[CR][LF]