Nautel Exporter Plus, Техническое руководство по эксплуатации, Страница: 168 / 186

Exporter Plus Technical Instruction Manual Troubleshooting
Page 10-2 Issue 1.0 2020-05-05
GPS related alarms
The
GPS STATUS
screen (see GPS Status Screen - see page 10-2 ) provides information on the
quality of GPS reception (i.e., number of satellites detected and HDOP) and the frequency
lock status.
Figure 10.1: GPS Status Screen
Frequency lock (
TIME SYNC
displayed) should be assured if the number of detected satellites
(
Sats
) by the GPS receiver is three or more and if the
HDOP
value is 4 or less. These values will
change as satellites move, but generally, if the antenna has a reasonably clear view of the sky,
then the values should be at least as good as described above.
The
Status
line can display various text depending on the quality of GPS reception and the
state of the Exporter Plus:
•
GPS ACQUIRE
indicates that no satellites are detected
•
PLL ALIGN
occurs briefly, if 1 PPS OK
•
PLL UNLOCKED
indicates pulling in
•
TIME SYNC
indicates a frequency lock
•
HOLDOVER
indictes the GPS receiver is coasting
When the Exporter Plus first boots up, the
Status
line indication should transition from
PLL
UNLOCKED
to
TIME SYNC
fairly quickly (less than 15 minutes).
If
PLL ALIGN
is displayed for more than a few seconds, suspect a hardware fault.
If
PLL UNLOCKED
is displayed for more than 15 minutes and the
Sats
and
HDOP
values are
acceptable, suspect a hardware fault.
If
HOLDOVER
is displayed, there is poor satellite reception. Attempt to minimize time in this
state, possibly by repositioning the GPS antenna.