Ag Leader GPS 1500 Operators Manual

GPS 1500 User Manual

PN 2005906 Rev. E

OVERVIEW

INTRODUCTION

The GPS 1500 is a smart antenna that tracks GPS and SBAS (WAAS and EGNOS) signals.

CABLE CONNECTIONS

DISPLAY

GPS OVERVIEW

The receiver is preconfigured and will work out of the box for most applications. When powered for the
first time, the reciever will perform a “cold start,” which involves acquiring the available GPS satellites in
view and the SBAS differential service.

GPS OPERATION

The GPS engine is always operating, regardless of the DGPS mode of operation. The GPS engine
automatically searches for GPS satellites, acquires the signals, and manages the navigation information
required for positioning and tracking.

Receiver Performance

The receiver finds four or more GPS satellites in the visible sky and uses the information provided by
those satellites to compute an appropriate position (typically within 2-3 meters). Since there is some
error in the GPS data calculations, the reciever also tracks a differential correction. It uses these
corrections to improve its position to less than 1 meter (3 feet)

There are two main aspects of receiver performance:

• Positioning

• Satellite acquisition quality

Satellites transmit coded information to the reciever in a specific frequency that allows the receiver to
calculate a distance to each satellite. GPS is essentially a timing system. The distance is calculated by
timing how long it takes the signal to go from the satellite to reciever.

1

The receiver uses a complex algorithm incorporating satellite locations and ranges to each satellite to
calculate the geographic location. Reception of any four or more of these signals allows a GPS receiver
to compute three-dimensional coordinates.

DIFFERENTIAL OPERATION

The Radio Technical Commission of Marine services (RTCM) has a differential service intended for
correction services. This includes the Space Based Augmentation Systems (SBAS), such as the Wide
Area Augmentation System (WAAS) and the European Geo-stationary Navigation Overlay System
(EGNOS). The GPS 1500 is compatible with each of these differential services.

SBAS

A SBAS-enabled reciever operates automatically anywhere within the coverage areas of the WAAS,
EGNOS or other SBAS programs.

WAAS and EGNOS explained

• WAAS is a free service of the Federal Aviation Administration (FAA) that allows regular GPS
positions to be improved to a DGPS level of accuracy. WAAS is available everywhere in the U.S.,
including Alaska, Hawaii and Puerto Rico. It can also be picked up in some of the border areas of
Mexico and Canada. There are no subscription charges incurred when using WAAS.

• EGNOS is a similar service that is available in Europe and western Russia.

Automatic SBAS tracking

The reciever will automatically scan and track satellite signals. This automatic tracking allows you to
focus on other aspects of differential operation without the need to tune the receiver. The GPS 1500
features two-channel SBAS tracking that provides an enhanced ability to maintain a lock on a SBAS
satellite when more than one satellite is in view. Thi s redundant tracking approach results in more
consistent tracking of a SBAS signal when in an area where signal blockage of a satellite is possible.

e-Dif

A reciever that is equipped with e-Dif capabilities can operate anywhere in the world where normal GPS
signals can be viewed. e-Dif can be used anywhere on the globe where a GPS lock can be achieved.

e-Dif is for our customers who are not able to receive other types of differential signals due to location or
budget.

Once the reciever computes a differential correction, the user can operate for unlimited time and provide
good relative accuracy. Alternatively, the operator can regularly update e-Dif to maintain absolute
accuracy (typically less than 1 meter over 40 minutes).

2

SETUP

UTILITY SETUP PROCEDURE

The default GPS settings are 4800 baud, 1 Hz GGA and VTG
NMEA strings.These settings will work for all Ag Leader
products.However, if the equipment that you are using requires
higher baud or Hertz rates, you many need to reconfigure the
GPS using the following procedure.

1. Download the Pocket Max PC.exe executable file from Ag
Leader’sweb site:
http://www.agleader.com/support.php?Page=downloads

2.Double click on Pocket Max PC.exe.

3. The Pocket Max PC program appears. On the Serial Port
setting, select the correct COM Port that the GPS is connected
to. Also, check the Auto Baud check box.

Note: If the utility cannot find the correct GPS receiver, use a different COM port and repeat. Also,

make sure that the GPS is powered.

Pocket PC with COM Port and Auto-Baud selected

4.Press the Search button. The utility then searches for the
correct GPS receiver.

Utility after finding correct GPS receiver with OK button showing

3

5. Once the utility finds the correct GPS receiver, the OK
button appears at the bottom of the window. Press the OK
button.

6.When the new window appears, click the Setup tab.

7. Under the “This Port” column, (located on the left-hand side of
the window) use the drop-down menu to select the correct Hz
rate, such as 5 Hz.

Selecting correct Hz rate on a NMEA string

ote:

N

Ag Leader’s products require the GGA and VTG NMEA strings. To find out the required NMEA

strings for other products, check with the manufacturer

8.At the bottom of the drop-down menu, select the correct
baud rate. These range between 4800 and 115,200.

•Ag Leader’s PF series monitors require a 4800 baud rate.

•Ag Leader® Integra, InSight and Edge require a 38400
ate

r

Dealer Training Invitation-updated 1_6_2010.pdf

2010

baud