YSI SonTek RiverSurveyor, Системное руководство

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SonTek/YSI Inc
RiverSurveyor System Manual (May 1, 2007)
97
GPS Data
The tabular data shown in the
GPS Data
box (
Figure 7-7
) relates to
GPS data (§
3.4
) and its quality as reported by a GPS receiver unit.
All data shown in this group requires either connection to a GPS
receiver unit (for real-time data collection) or a file containing
GPS data (for post-processing). To display this information on
screen, use
View|Display Data|Show GPS Data
.
•
Lon
– Vessel longitude as last reported by the GPS unit.
•
Lat
– Vessel latitude as last reported by the GPS unit.
•
Magnetic Declin.
– The magnetic declination of the present
location. This value is either manually entered in the
User
Setup
dialog box (
Figure 6-4
) or read directly from the GPS
unit when the unit is connected (§
3.4
). Note that this value
remains static for the entire measurement (i.e., it is not dy-
namically read by
RiverSurveyor ).
•
Invalid Satellites
– The number of times there have been insufficient satellites to establish a
valid GPS lock.
•
# Satellites
– The number of satellites the GPS unit is using to determine present position.
•
Sats Changes
– The number of times that
# Satellites
has changed.
•
Altitude
– The elevation above sea level reported by the GPS unit.
•
Delta Alt
– The maximum change in altitude during the transect.
•
HDOP
– Horizontal Dilution of Precision is the degree of uncertainty in the horizontal posi-
tions (latitude and longitude) report by the GPS unit.
•
Delta HDOP
– The maximum change in the HDOP during the entire transect. A value greater
than 1 suggests that GPS data may be unreliable.
•
GC-BC
– Shows the angle in degrees of the average GPS course since the start of the tran-
sect minus the ADP bottom-track course (§
3.3.6
). A value near 0 is desired.
•
D(BT) / D(GPS)
– Shows the ratio of the bottom-track distance made good to the GPS dis-
tance made good. A value near 1 is desired (§
3.3.6
).
Sensor Data
The tabular data shown in the
Sensor Data
box (
Figure 7-8
) relates
to information collected when sensor data is available. To display
this information on screen, use
View|Show Sensor Display
.
•
Heading
– Shows vessel heading based on the
Track Display
selection on the
Processing
toolbar, either
BT
(bottom track)
or
GPS
. If
BT
is selected, the reading is taken from the
ADP’s internal compass, and depending on ADP alignment,
this reading may not agree with the vessel’s gyrocompass.
•
Pitch
and
Roll
– Shows the pitch and roll angles of the ADP
when the last profile was processed. Depending on ADP
alignment, this may not match the vessel’s pitch/roll angles.
•
Avg Heading
– The mean heading for the entire transect.
Figure 7-7. GPS Data
Figure 7-8. Discharge Data