Refraction Technology 130-01, Operation Manual

Page: 107 / 114

Doc-1301-Ops Rev 2.9.1 10/30/08
Refraction Technology, Inc. 93
018:09:06:45 INTERNAL CLOCK TIME SET
During the first GPS power-on cycle the DAS waits 20 minutes, after initial LOCK,
in case the GPS reports an additional 1 second shift due to a difference in its
pages.
This shift can be +/- 1 second from the current reported time.
This shift only occurs once and is rare.
If acquisition was started as soon as the GPS declared LOCK and this shift occurs
within the 20 minutes of GPS LOCK then the data prior to this shift will off by the
+/- second, as reported in the example below.
018:09:21:50 DSP CLOCK SET: OLD = 04:018:09:21:50.000, NEW= 04:018:09:21:51.000
The DAS internal clock has changed from the old value to the new value.
This third time set will either be +/- 1 second.
018:09:21:51 DSP CLOCK DIFFERENCE: +1 SECS AND 0 MSECS
Indicates there was a difference of +1 second and any data recorded between the
second DSP clock set needs to be corrected by +1 second.
018:09:06:45 DSP CLOCK HAS CHANGED 3 TIMES
Indicates the DAS has made three changes to the internal clock since power up.
018:09:07:22 INTERNAL CLOCK PHASE ERROR OF -1 USECONDS
The DAS internal clock or 1 Hz is compared to the 130-GPS 1 Hz periodically and
the difference is noted. In this case: -1 µS
For the first cycle of DAS/130-GPS power the phase error will be checked every
minute for 15 minutes. Each additional lock will have only one phase error
check/message.
301:07:30:58 INTERNAL CLOCK PHASE ERROR OF 18 USECONDS
The DAS internal clock or 1 Hz is compared to the 130-GPS 1 Hz periodically and
the difference is noted.
In this case: 18 µS
301:10:13:47 INTERNAL CLOCK PHASE ERROR OF 223 MSECONDS
The DAS internal clock or 1 Hz is compared to the 130-GPS 1 Hz periodically and
the difference is noted.
In this case: 223 mS
357:09:44:53 GPS: POSITION: N23:18:20.04 E101:23:29.58 +01610M
The DAS prints the 130-GPS position information given by this 130-GPS after lock.