NTS 01 Rev 1 – User Manual March 2006
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Page 23 of 31
Tekron International Ltd
PO Box 31 285 Lower Hutt 6009 New Zealand
tel:
+64 4 566 7722
fax:
+64 4 569 9272
email:
Satellite Trails (green lines), and a Minimum Elevation plot (blue lines) can be turned on and off
from the “GPS” menu option on this page. Over time, the blue line will show the horizon line,
as well as areas where there is poor GPS constellation coverage. The example in fig is from
Wellington, New Zealand and clearly shows that there is poor satellite coverage in southern
latitudes.
It is important, when operating NTS01 in extreme southern latitudes, to ensure that the
antenna is positioned with a clear view of the sky to the north if reliable performance is to
be guaranteed. The opposite situation occurs when operating in extreme northern
latitudes, where a clear view of the sky to the south is desirable.
Satellite Signal Strength Indicator
The received signal strength of satellites being used for time calculations are shown here.
The white numbers are a cross reference to the satellite number on the Visible Satellites display.
Location and UTC Time
This panel shows the current position and UTC time data held in NTS01’s GPS receiver. Once
the Receiver has successfully tracked satellites and computed time and position, these
parameters can no longer be changed externally. However, it IS possible to set time and position
if the Receiver has not achieved a satellite fix since power on, or if the Receiver has had all
existing data cleared before attempting to set time and position. The Menu Selection
“GPS/Advanced” gives the user access to these functions. Note that if the advanced GPS menu
option “Clear Location Time and Almanac” is used, then the GPS Receiver may take some time
(up to half an hour or more) to recover unless the user is able to assist by entering a known
position and an approximate time.
The “
Clear Location Time and Almanac” option in NTS01 should ONLY be executed by
experienced technical personnel under controlled circumstances, such as to facilitate
laboratory testing of external equipment as described below.
The ability to force any time and date into the instrument means that NTS01 can be used as a
convenient signal source for testing the ability of externally attached equipment to correctly
process received time messages through particularly critical time transitions, (such as the 28/29
Feb rollover during leap years). In units fitted with the Local Time Display Firmware Option, It
also allows the correct operation over daylight savings transitions to be conveniently checked,
by setting the time to just a short period prior to the expected transition time then waiting for the
transition to tick by.
