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D Logs Summary
220 MiLLennium GPSCard SW Version 4.503/4.52 Command Descriptions Manual Rev 2
TM1A/B Time of 1PPS
This log provides the time of the GPSCard 1PPS, normally high, active low pulse (1 millisecond), where falling
edge is reference, in GPS week number and seconds into the week. The TM1A/B log follows a 1PPS pulse. It also
includes the receiver clock offset, the standard deviation of the receiver clock offset and clock model status. This
log will output at a maximum rate of 1 Hz.
TM1A
Structure:
Example:
$TM1A,794,414634.999999966,-0.000000078,0.000000021,-9.999999998,0*57[CR][LF]
TM1B
Format: Message ID = 03 Message byte count = 52
$TM1A week seconds offset offset std
utc offset cm status *xx [CR][LF]
Field # Field type Data Description Example
1
$TM1A Log header $TM1A
2
week GPS week number 794
3
seconds GPS seconds into the week at the epoch coincident with the 1PPS
output strobe (receiver time)
414634.99999996
6
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:
GPS time = receiver time - (offset)
-0.000000078
5
offset std Standard deviation of receiver clock offset, in seconds 0.000000021
6
utc offset This field represents the offset of GPS time from UTC time, computed
using almanac parameters. To reconstruct UTC time, algebraically
subtract this correction from field 3 above (GPS seconds).
UTC time = GPS time + (utc offset)
-9.999999998
7
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
0
8
*xx Checksum *57
9 [CR][LF] Sentence terminator [CR][LF]
Field # Data Bytes Format Units Offset
1 Sync 3 char 0
(header) Checksum 1 char 3
Message ID 4 integer 4
Message byte count 4 integer 8
2 Week number 4 integer weeks 12
3 Seconds of week 8 double seconds 16
4 Clock offset 8 double seconds 24
5 Stddev clock offset 8 double seconds 32
6 UTC offset 8 double seconds 40
7 Clock model status 4 integer 48