Odetics
Telecom
GPStar
plus
Model 365
365-8006
Getting Started 4 - 2
When power is applied, the front panel display backlight illuminates, followed shortly
thereafter with the
Time and Satellite
screen.
GPS TFOM:9 Jan 06,1980 / 006:00:01:53
≡
Warm-Up Sats:01s 02s 17s 24s 29s
The above screen indicates the unit's internal GPS receiver is operating in the Cold
Start mode (as indicated by the start date of GPS time:
Jan 06, 1980),
the number of
the satellite(s) being searched, the selected Time Reference is
GPS
, and the Time
Figure Of Merit (
TFOM
) of the unit's time.
Note: The indicated Time Reference
GPS
and
TFOM:9
are shown for illustration only.
The actual Time Reference shown is the one selected during the prior operation of the
unit, and the actual
TFOM
value may be different.
Further operation is automatic. In order to reach steady-state operation, the unit must
know the position of the antenna. The unit's internal GPS receiver must track at least 3
satellites to collect enough information to compute the antenna position. During Cold
Start, the unit operates in the
Position Averaging
position mode and uses data from the
satellites to calculate the antenna position. Although the unit does synchronize to GPS
and starts to discipline the internal oscillator during the
Position Averaging
period, it is
at a reduced accuracy. After operating in the
Position Averaging
mode for a minimum of
1 day, the unit automatically switches to the
Known
position mode using the calculated
averaged antenna position. The greatest accuracy is obtained while operating in the
Known
mode with the exact antenna position information.
The user can shorten the time required to track satellites and achieve synchronization,
by selecting the
Known
position mode and entering the actual antenna position
accurate to seconds of arc. The Antenna Delay compensation should also be entered.
Refer to paragraph 4.5, Antenna Position/Mode Selection, and paragraph 4.6, Antenna
Cable Delay Compensation Selection.
Note: An incorrect value for the antenna position can cause the unit to search for the
wrong satellites, and will degrade the timing/frequency accuracy of the output signals or
even prevent the tracking of any satellite
.
Warm Start -
At subsequent application of power, after the unit has stored a valid
almanac, the unit defaults to the Warm Start mode and the position solution defaults to
the mode that was selected during prior operation. If the unit initializes in the Warm
Start mode, the following screen appears:
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