D Logs Summary
MiLLennium GPSCard SW Version 4.503/4.52 Command Descriptions Manual Rev 2 149
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.

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
2week GPS week number 637
3seconds GPS seconds into the week 511323.00
4offset 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: GPS time = receiver time - (offset)
-4.628358547E-003
5drift Receiver clock drift, in seconds per second. A positive drift implies that
the receiver clock is running faster than GPS Time. -2.239751396E-007
6SA 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.
2.061788299E-006
7offset std Standard deviation of receiver cloc k offset, in seconds 5.369997167E-008
8drift std Standard deviation of receiver drift, in seconds per second 4.449097711E-009
9cm status Receiver Clock Model Status where 0 is valid and val ues from -20 to -1
imply that the model is in the process of stabilization 0
10 *xx Checksum *7F
11 [CR][LF] Sentence terminator [CR][LF]