Laboratory Exercise 1
Acquiring Data in the Field
"The Global Positioning System and GIS, An Introduction",
Michael Kennedy, Ann Arbor Press, 1996, Part 2, ISBN 1-57504-017-4.
This laboratory consists of an introduction to the use of the Trimble's
GeoExplorer II mapping system consisting of a pocket sized
GPS data collector and Pathfinder Office - GPS processing software.
In this exercise, you will learn the basics of obtaining GPS field data
using the GeoExplorer II. You will become familiar with GeoExplorer
II menu options, how to set up the unit for data gathering, and
then how to acquire data in the field.
For more information on these concepts, refer to the Trimble
With the supervision of your instructor, or lab coordinator, checkout
the GeoExplorer II, being sure that the battery is fully
charged and connected to the GeoExplorer II. To move between
menus, use the ESC key to move up the menu chain, and the CMD
key (the one in the center with the yellow diamond) to move down the menu
chain Use the UP and DOWN arrow keys to change numeric information.
A. INSIDE PREPARATION:
Before going into the field, set the collection parameters as follows:
- Turn on the unit (black button above the word "Trimble").
- Press the ESC key until the main menu appears.
- Use the UP or DOWN arrows to get to 6. Configuration
- Press the CMD key and a new Configuration Menu appears.
- Go to 1. Rover Operations Make Sure that the following parameters are
Pos Mode: 3D
Elev Mask: 15
SNR Mask: 4
PDOP Mask: 6
Antenna Ht: 1.00
Log DOPs: Off
File Prefix: R (do not change)
Not in Feature Rate: 3s
Ignore the rest of the settings. Press ESC and return to Configuration
- From the Configuration menu, go to Coordinates, press CMD and select
UTM , ESC
- From the Configuration menu, go to DATUM and select
WGS 84 (World
- From the Configuration menu, go to UNITS, CUSTOM, DISTANCE (select
- From the Configuration menu, go to UNITS, CUSTOM, ANGULAR (select
- From the Configuration menu, go to UNITS, CUSTOM, VELOCITY (select
- From the Configuration menu, go to UNITS, CUSTOM, ALTITUDE UNITS
(select meters), ESC
- From the Configuration menu, go to UNITS, CUSTOM, ALTITUDE REFERENCE
(select Geoid (MSL)), ESC
- From the Configuration menu, go to UNITS, CUSTOM, NORTH REFERENCE
(select Magnetic North), ESC, ESC, ESC.
- From the Configuration menu, go to DATE & TIME, CMD, SET
LOCAL TIME, CMD, Use UP and DOWN arrows to set Local-UTC:
-4:00 (For Eastern Daylight Savings Time, -5 for Eastern Standard Time), ESC
- From the SET LOCAL TIME menu, select TIME DISPLAY, CMD,
select Local 12 Hours.
- Verify all settings recorded above, then turn unit off by holding down
the ON/OFF button for more than five seconds. The unit will then shut off.
- Before collecting data, prepare a log sheet with which you will manually
record the following information:
Members of the group.
The date and time.
A general description of the location.
The starting time and ending time of the data collection.
The rover filename.
The satellite numbers being recorded.
The log rate and number of positions measured.
The amount of memory available.
The hours of charge left in battery pack, and the amount of time it is
used in the session.
B. OUTSIDE DATA COLLECTION
- Move to a spot selected by the instructor. Be sure to bring a tripod
and the Trimble Tripod Mounting Bracket.
- 180 readings will be tak en every three seconds, or 20 readings per
minute, so the session should end about 9 minutes after it begins. It is
best to begin readings so that they will NOT span over two hour increments,
i.e. start 10:58 end 11:07.
- When you are ready to collect data, turn the unit on
- Go to the GPS Status menu from the maim menu, then chose 1.
Satellite Tracking. Holding the unit at arms length (so your head
and body do not block the satellite transmissions) note the satellite n
umbers being pick up and record them in the log.
- Attach GeoExplorer II to tripod and position over designated spot.
- Go to the Data Capture menu from the main menu.
- Select Open Rov. File. BE SURE TO OPEN ROV. FILE, NOT BASE
- If enough satellites are present, the unit will begin to collect data.
Note the start time.
- Note the Rover File Name in the format Rmmddhhi, where mm is the month,
dd is the day and hh is the UTC hour, i is an index number, A, B, etc.,
to keep individual files separate.
- After nine minutes, Close file.
- Go to Review File and note log rate and number of positions
- Finish your log entries.
Transcribe your hand entries in the log, using WORD or equivalent word
processing software. Be sure to include the names of all group members.
Keep the WORD report for your records. Submit report via e-mail to:email@example.com