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Chapter 3 Visual User Interface
Using and Reading the Visual User Interface (the Receiver Status
Screen)
3-4 Operating and Programming Guide
Figure 3-1. Receiver Status Screen at Powerup
The ACQUISITION area of the screen is telling you that no satellites
have been tracked. The identification numbers of several satellites
appear in the Not Tracking column. The asterisk next to the satellite
identification number, or pseudorandom noise code (PRN), indicates
the Receiver is attempting to track it.
The current time and date are shown in the Time quadrant of the
ACQUISITION area. The default power-up setting, indicated by [?], is
corrected when the first satellite is tracked. Since the Receiver is not
tracking any satellites, the GPS 1 PPS reference signal is invalid.
An accurate position is necessary to derive precise time from GPS. The
Position quadrant indicates that the Receiver is in survey mode, which
uses GPS to determine the position of the GPS antenna. This process
has not yet started, since position calculations can be performed only
while tracking four or more satellites. INIT LAT, INIT LON, and INIT
HGT are the initial estimate of the true position. These coordinates are
refined by the survey process. The Receiver uses this position and the
time-of-day to select satellites to track. Therefore, you can reduce
satellite acquisition time by specifying a close approximation of
position and time.
Now, let’s send the
:SYSTEM:STATUS?
query again to see what kind of
progress the Receiver has made.
SYNCHRONIZATION
Receiver Status
---------------------------- ----------------------------
[
Outputs Invalid
]
.........................................
.............................................
......................................................
ACQUISITION
ELEV MASK
Not Tracking: 6
Locked
TFOM
FFOM
UTC
ANT DLY
MODE
INIT LAT
INIT LON
INIT HGT
HEALTH MONITOR
HOLD THR
PRN
Recovery
Holdover
Power-up:GPS acquisition
SmartClock Mode
Tracking: 0
Self Test: OK Int Pwr: OK Oven Pwr: OK OCXO: OK EFC: OK GPS Rcv: OK
[ OK ]
1PPS TI
Time
GPS 1PPS Invalid: not tracking
Position
Reference Outputs
El Az
*1 -- ---
*6 -- ---
10 deg
9
3
1.000 us
--
[GPS 1PPS Invalid]
12:00:00[?] 01 Jan 1996
0 ns
Survey: 0% complete
N
W
0:00:00.000
0:00:00.000
0 m (GPS)
>>
*9 -- ---
*14 -- ---
*attempting to track
*22 -- ---
*24 -- ---
Holdover Uncertainty
Predict --
Suspended:track <4 sats