Section 2: Installation
Page 2-14
NetClock/GTP Instruction Manual
Tracking
: The receiver must track at least one qualified satellite to operate. Typically,
the receiver shall track 6 or more satellites with the Model 8225 GPS Antenna. If the
Model 8228 indoor window mount antenna is used, the receiver will typically track 4
or more satellites.
GPS State
: Under normal operation the receiver will indicate 3-D Fix. A Searching or
2-D Fix message indicates that fewer than 4 qualified satellites are currently tracked.
DOP
: Dilution of Precision indicates the degree of uncertainty of a Position Fix. The
DOP value shall be 0
≤
DOP<10 when in 3-D Fix mode.
Quality
: A PASSED message indicates the receiver is tracking at least one qualified
satellite. A FAILED message indicates the received GPS signals did not meet
minimum requirements.
Satellite Data
: Data on each satellite currently tracked is provided in table form.
The CHAN column represents the GPS Receiver Channel Number, 1 through 8.
VID is the Vehicle (satellite) Identification Number, 1 through 37.
The MODE column provides the Channel Tracking Mode for each satellite. The GPS
qualifying algorithm accepts only satellites having a Mode value of 08.
The relative signal strength of each satellite currently tracked is found in the STREN
column. The maximum signal level is 55.
The satellite status flag code is found in the STAT column. Typically, the STAT value is
A2.
If the receiver does not meet the minimum requirements described above, refer to
Section 5,
Service Information
, for troubleshooting assistance.
2.8.2 Tracking
Histogram
The
D
isplay Tracking
H
istogram command,
DH
, is used to evaluate the long term
reception quality. The tracking histogram records the number of satellites tracked and
qualified every second. At the end of the hour, a log is created and the counters are
restarted. The command responds with the last four hourly entries and the histogram
currently in process. A complete description of the
DH
command is found in Section 4
of this manual.
Allow the receiver to operate for at least 5 hours before evaluating the tracking
histogram. Issue the DH command as shown below:
Type:
DH <ent>
