Trimble AgGPS 252 User Manual

F

Version 1.00

Revision A

Part Number 55510-00-ENG

February 2004

AgGPS® 252 Receiver

User Guide

Ag252_100A_UserGde_ENG.book Page i Wednesday, January 28, 2004 5:42 PM

ii AgGPS 252 Receiver User Guide

Contact Information

Trimble Navigation Limited
Agriculture Business Area
9290 Bond Street, Suite 102
Overland Park, KS 66214
USA

[phone] Phone

[e-mail]
www.trimble.com

Copyright and Trademarks

© 2004, Trimble Navigation Limited. All rights
reserved.

Trimble, the Globe & Triangle logo, and AgGPS are
trademarks of Trimble Navigation Limited, registered in
the United States Patent and Trademark Office and other
countries. EVEREST, MS750, and SiteNet are
trademarks of Trimble Navigation Limited.

Microsoft and ActiveSync are either registered
trademarks or trademarks of Microsoft Corporation in
the United States and/or other countries. All other
trademarks are the property of their respective owners.

Release Notice

This is the February 2004 release (Revision A) of the
AgGPS 252 Receiver User Guide, part number
55510-00-ENG. It applies to version 1.00 of the AgGPS
252 receiver.

The following limited warranties give you specific legal
rights. You may have others, which vary from
state/jurisdiction to state/jurisdiction.

Hardware Limited Warranty

Trimble Navigation Limited warrants that this hardware
product (the “Product”) will perform substantially in
accordance with published specifications and be
substantially free of defects in material and
workmanship for a period of one (1) year starting from
the date of delivery. The warranty set forth in this
paragraph shall not apply to software products.

Software License, Limited Warranty

This Trimble software product, whether provided as a
stand-alone computer software product, built into
hardware circuitry as firmware, embedded in flash
memory, or stored on magnetic or other media, (the
“Software”) is licensed and not sold, and its use is
governed by the terms of the relevant End User License
Agreement (“EULA”) included with the Software. In the
absence of a separate EULA included with the Software
providing different limited warranty terms, exclusions
and limitations, the following terms and conditions shall
apply. Trimble warrants that this Trimble Software
product will substantially conform to Trimble’s

applicable published specifications for the Software for
a period of ninety (90) days, starting from the date of
delivery.

Warranty Remedies

Trimble's sole liability and your exclusive remedy under
the warranties set forth above shall be, at Trimble’s
option, to repair or replace any Product or Software that
fails to conform to such warranty (“Nonconforming
Product”) or refund the purchase price paid by you for
any such Nonconforming Product, upon your return of
any Nonconforming Product to Trimble in accordance
with Trimble’s standard return material authorization
procedures.

Warranty Exclusions and Disclaimer

These warranties shall be applied only in the event and
to the extent that (i) the Products and Software are
properly and correctly installed, configured, interfaced,
maintained, stored, and operated in accordance with
Trimble's relevant operator's manual and specifications,
and; (ii) the Products and Software are not modified or
misused. The preceding warranties shall not apply to,
and Trimble shall not be responsible for defects or
performance problems resulting from (i) the
combination or utilization of the Product or Software
with hardware or software products, information, data,
systems, interfaces or devices not made, supplied or
specified by Trimble; (ii) the operation of the Product or
Software under any specification other than, or in
addition to, Trimble's standard specifications for its
products; (iii) the unauthorized, installation,
modification, or use of the Product or Software; (iv)
damage caused by accident, lightning or other electrical
discharge, fresh or salt water immersion or spray; or (v)
normal wear and tear on consumable parts (e.g.,
batteries). Trimble does not warrant or guarantee the
results obtained through the use of the Product.

THE WARRANTIES ABOVE STATE TRIMBLE'S ENTIRE
LIABILITY, AND YOUR EXCLUSIVE REMEDIES,
RELATING TO PERFORMANCE OF THE PRODUCTS
AND SOFTWARE. EXCEPT AS OTHERWISE
EXPRESSLY PROVIDED HEREIN, THE PRODUCTS,
SOFTWARE, AND ACCOMPANYING
DOCUMENTATION AND MATERIALS ARE PROVIDED

“

AS-IS” AND WITHOUT EXPRESS OR IMPLIED
WARRANTY OF ANY KIND BY EITHER TRIMBLE
NAVIGATION LIMITED OR ANYONE WHO HAS BEEN
INVOLVED IN ITS CREATION, PRODUCTION,
INSTALLATION, OR DISTRIBUTION INCLUDING, BUT
NOT LIMITED TO, THE IMPLIED WARRANTIES OF
MERCHANTABILITY AND FITNESS FOR A
PARTICULAR PURPOSE, TITLE, AND
NONINFRINGEMENT. THE STATED EXPRESS
WARRANTIES ARE IN LIEU OF ALL OBLIGATIONS OR
LIABILITIES ON THE PART OF TRIMBLE ARISING
OUT OF, OR IN CONNECTION WITH, ANY PRODUCTS
OR SOFTWARE. SOME STATES AND JURISDICTIONS
DO NOT ALLOW LIMITATIONS ON DURATION OR
THE EXCLUSION OF AN IMPLIED WARRANTY, SO

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AgGPS 252 Receiver User Guide iii

THE ABOVE LIMITATION MAY NOT APPLY TO YOU.
TRIMBLE NAVIGATION LIMITED IS NOT
RESPONSIBLE FOR THE OPERATION OR FAILURE OF
OPERATION OF GPS SATELLITES OR THE
AVAILABILITY OF GPS SATELLITE SIGNALS.

Limitation of Liability

TRIMBLE’S ENTIRE LIABILITY UNDER ANY
PROVISION HEREIN SHALL BE LIMITED TO THE
AMOUNT PAID BY YOU FOR THE PRODUCT OR
SOFTWARE LICENSE. TO THE MAXIMUM EXTENT
PERMITTED BY APPLICABLE LAW, IN NO EVENT
SHALL TRIMBLE OR ITS SUPPLIERS BE LIABLE FOR
ANY INDIRECT, SPECIAL, INCIDENTAL OR
CONSEQUENTIAL DAMAGES WHATSOEVER UNDER
ANY CIRCUMSTANCE OR LEGAL THEORY RELATING
IN ANY WAY TO THE PRODUCTS, SOFTWARE AND
ACCOMPANYING DOCUMENTATION AND
MATERIALS, (INCLUDING, WITHOUT LIMITATION,
DAMAGES FOR LOSS OF BUSINESS PROFITS,
BUSINESS INTERRUPTION, LOSS OF BUSINESS
INFORMATION, OR ANY OTHER PECUNIARY LOSS),
REGARDLESS WHETHER TRIMBLE HAS BEEN
ADVISED OF THE POSSIBILITY OF ANY SUCH LOSS
AND REGARDLESS OF THE COURSE OF DEALING
WHICH DEVELOPS OR HAS DEVELOPED BETWEEN
YOU AND TRIMBLE. BECAUSE SOME STATES AND
JURISDICTIONS DO NOT ALLOW THE EXCLUSION OR
LIMITATION OF LIABILITY FOR CONSEQUENTIAL OR
INCIDENTAL DAMAGES, THE ABOVE LIMITATION
MAY NOT APPLY TO YOU.

NOTE: THE ABOVE LIMITED WARRANTY
PROVISIONS MAY NOT APPLY TO PRODUCTS OR

SOFTWARE PURCHASED IN THE EUROPEAN UNION.

PLEASE CONTACT YOUR TRIMBLE DEALER FOR
APPLICABLE WARRANTY INFORMATION.

Notices
USA

NOTE – FCC Part 15 rules; paragraph 15.105

This equipment has been tested and found to comply
with the limits for a Class A digital device, pursuant to
Part 15 of the FCC Rules. These limits are designed to
provide reasonable protection against harmful
interference when the equipment is operated in a
commercial environment. This equipment generates,
uses, and can radiate radio frequency energy and, if not
installed and used in accordance with the instruction
manual, may cause harmful interference to radio
communications. Operation of this equipment in a
residential area is likely to cause harmful interference, in
which case, you, the user, will be required to correct the
interference at your own expense.

If this equipment does cause harmful interference to
radio or television reception, which can be determined
by turning the equipment off and on, the user is
encouraged to try to correct the interference by one or
more of the following measures:

– Reorient or relocate the receiving antenna.
– Increase the separation between the equipment and

the receiver.

– Connect the equipment into an outlet on a circuit

different from that to which the receiver is connected.

– Consult the dealer or an experienced radio/TV

technician for help.

Changes and modifications not expressly approved by
the manufacturer or registrant of this equipment can
void your authority to operate this equipment under
Federal Communications Commission rules.

Europe

This product has been tested and found to comply with
the requirements for the European Directive
75/322/EEC as amended by 2000/2/EC thereby
satisfying the requirements for e-mark compliance for
use in agricultural vehicles in the European Economic
Area (EEA).

This product has been tested and found to comply with
the requirements for a Class A device pursuant to
European Council Directive 89/336/EEC on EMC,
thereby satisfying the requirements for CE Marking and
sale within the European Economic Area (EEA).

C

Warning – This is a Class A product. In a domestic

environment this product may cause radio
interference in which case you may be required to
take adequate measures.

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iv AgGPS 252 Receiver User Guide

Declaration of Conformity

This product conforms to the following standards, and therefore complies with the requirements of the R&TTE
Directive 1999/5/EC, which specifies compliance with the essential requirements of EMC Directive 89/336/EEC and
Low Voltage Directive 73/23/EEC.

The technical file is maintained at Trimble Navigation Limited, 749 North Mary Avenue, PO Box 3642, Sunnyvale,
CA 94088-3642, USA.

EMC Emissions BSEN 55022:1998 (W/A1:00) Class A
EMC Immunity EN 55024:1998
Safety EN 60950:2000
Mark First Applied 03

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AgGPS 252 Receiver User Guide v

Contents

1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . 1

Warnings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Related Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Technical Assistance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Your Comments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

2 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Standard Features of the AgGPS 252 Receiver . . . . . . . . . . . . . . . . 4

Receiver Connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Receiver Input/Output . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

LED Indicator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

GPS Positioning Methods. . . . . . . . . . . . . . . . . . . . . . . . . . 10

RTK GPS positioning . . . . . . . . . . . . . . . . . . . . . . . . 10

Differential GPS positioning (DGPS) . . . . . . . . . . . . . . . . 11

Autonomous GPS positioning . . . . . . . . . . . . . . . . . . . . 12

Sources of Error in GPS Positioning . . . . . . . . . . . . . . . . . . . . 13

Coordinate systems. . . . . . . . . . . . . . . . . . . . . . . . . . 15

3 Installing the Receiver. . . . . . . . . . . . . . . . . . . . 17

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

System Components . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

Optional extra . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

Mounting the Receiver . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

Choosing a location . . . . . . . . . . . . . . . . . . . . . . . . . 19

Environmental conditions . . . . . . . . . . . . . . . . . . . . . . 20

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Contents

vi AgGPS 252 Receiver User Guide

Electrical interference . . . . . . . . . . . . . . . . . . . . . . . . 20

Connecting to an External Device . . . . . . . . . . . . . . . . . . . . . 21

Connectors and Pinouts . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

Port A . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

Port B . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

4 Configuring the Receiver . . . . . . . . . . . . . . . . . . 27

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

AgRemote Home Screen . . . . . . . . . . . . . . . . . . . . . . . . . . 29

Configuring Differential GPS. . . . . . . . . . . . . . . . . . . . . . . . 30

OmniSTAR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

WAAS/EGNOS . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

Configuring the AgGPS 252 Receiver to Operate in RTK Mode . . . . . . 33

Configuring the Communication Ports . . . . . . . . . . . . . . . . . . . 33

Configuring input/output communication . . . . . . . . . . . . . . 34

5 Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . 39

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40

Problems and Solutions . . . . . . . . . . . . . . . . . . . . . . . . . . . 40

Troubleshooting Flowcharts . . . . . . . . . . . . . . . . . . . . . . . . 48

A Specifications . . . . . . . . . . . . . . . . . . . . . . . . 55

AgGPS 252 Receiver . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55

GPS Channels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56

L-Band Satellite Differential Correction Receiver . . . . . . . . . . . . . 58

Receiver Default Settings . . . . . . . . . . . . . . . . . . . . . . . . . . 58

B Third-Party Interface Requirements . . . . . . . . . . . . 59

Third-Party Software . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59

Third-Party Hardware. . . . . . . . . . . . . . . . . . . . . . . . . . . . 61

Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65

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CHAPTER

1

AgGPS 252 Receiver User Guide 1

Introduction 1

Welcome to the AgGPS 252 Receiver User Guide. This manual:

• Describes how to install and configure the Trimble

®

AgGPS

®

252 receiver.

• Provides guidelines for connecting the receiver to an external
device.

• Provides guidelines for using the AgRemote utility to view and
configure the receiver correction sources and other operating
parameters.

Even if you have used other Global Positioning System (GPS)
products before, Trimble recommends that you spend some time
reading this manual to learn about the special features of this product.

If you are not familiar with GPS, go to the Trimble website at

www.trimble.com for an interactive look at Trimble and GPS.

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1 Introduction

2 AgGPS 252 Receiver User Guide

1.1 Warnings

Always follow the instructions that accompany a warning.

C

Warning – Indicates a potential hazard or unsafe practice that could result
in injury or property damage.

1.2 Related Information

Release notes describe new features, provide information that is not
included in the manuals, and identify changes to the manuals. You can
download release notes from the Trimble website.

1.3 Technical Assistance

If you have a problem and cannot find the information you need in the

product documentation, contact your local Trimble Reseller.

1.4 Your Comments

Your feedback about the supporting documentation helps us to
improve it with each revision. Email your comments to

[e-mail].

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CHAPTER

2

AgGPS 252 Receiver User Guide 3

Overview 2

In this chapter:

 Introduction
 Standard Features of the AgGPS 252 Receiver
 Receiver Connections
 Receiver Input/Output
 LED Indicator
 GPS Positioning Methods
 Sources of Error in GPS Positioning

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2 Overview

4 AgGPS 252 Receiver User Guide

2.1 Introduction

This chapter describes the AgGPS 252 receiver and gives an overview

of GPS, DGPS, and related information. When used with a Real-Time

Kinematic (RTK) base station, the AgGPS 252 receiver provides RTK

positioning for high-accuracy, centimeter-level applications. For
physical specifications, see Appendix A, Specifications.

2.2 Standard Features of the AgGPS 252 Receiver

A standard AgGPS 252 receiver provides the following features:

• 12 GPS (C/A-code) tracking channels, code carrier channels

• Horizontal RTK positioning accuracy 2.5 cm (0.98 in) + 2 ppm,
2 sigma; vertical RTK positioning accuracy 3.7 cm (1.46 in)
+ 2ppm, 2sigma

• Submeter differential accuracy (RMS), assuming at least five
satellites and a PDOP of less than four

• Combined GPS/DGPS receiver and antenna

• System level cable

• AgRemote utility with four-button keypad to configure and view

system properties (download from the Trimble website at

www.trimble.com)

• LED status indicator

• The receiver outputs a 1 PPS (pulse per second) strobe signal on
both ports. This signal enables an external instrument to
synchronize its internal time with a time derived from the very
accurate GPS system time.

• WAAS differential correction compatibility

• AgGPS 170 Field Computer compatibility

• EVEREST™ multipath rejection technology

• OmniSTAR VBS and HP positioning compatibility

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AgGPS 252 Receiver User Guide 5

Overview 2

• Two ports that support both CAN 2.0B and RS-232:

CAN

– J1939 and NMEA 2000 messages

Note – The AgGPS 252 is ISO 11783 compliant. It supports
some ISO 11783 messages.

RS-232

– NMEA-0183 output: GGA, GLL, GRS, GST, GSA, GSV,

MSS, RMC, VTG, ZDA, XTE (the default NMEA
messages are GGA, GSA, VTG, and RMC)

Note – PTNLDG, PTNLEV, PTNLGGK, PTNLID, and
PTNLSM are Trimble proprietary NMEA output messages.

– RTCM SC-104 output

– Trimble Standard Interface Protocol (TSIP) input and

output

2.3 Receiver Connections

Figure 2.1 shows the connector ports and the LED indicator on the

AgGPS 252 receiver.

Figure 2.1 AgGPS 252 receiver connector ports

LED indicator

Port A Port B

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2 Overview

6 AgGPS 252 Receiver User Guide

The two connectors (Port A and Port B) can perform the following
functions:

• accept power

• accept TSIP, RTCM, ASCII, and (if enabled) CMR inputs

• output RTCM, TSIP, and NMEA messages

• output 1 PPS signals

• provide support for the J1939 (CAN) serial bus

For more information about the inputs, outputs, and LED indicators,
see the information in the rest of this section.

2.4 Receiver Input/Output

The AgGPS 252 receiver data/power cable (P/N 50166) connects to a

receiver connector port to supply power. It also enables the following
data exchanges:

• TSIP, RTCM, and ASCII input from an external device

The receiver is able to receive ASCII data from an external
device, convert this data into an NMEA message, and export the
message to another device. TSIP command packets configure
and monitor GPS and DGPS parameters. The receiver is also
able to accept RTCM data from an external device, such as a
radio.

• CMR input from an external device

If the receiver is to be used in RTK mode, set the port that is

connected to the radio to the RtkLnk protocol. This protocol

enables the receiver to receive CMR messages.

• TSIP and NMEA output to an external device

When you are using an external radio, the receiver can also
receive DGPS corrections.

TSIP is input/output when communicating with AgRemote.

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AgGPS 252 Receiver User Guide 7

Overview 2

NMEA is output when the receiver is exporting GPS position
information to an external device, such as a yield monitor, or to
a mapping software program.

For more information on the National Marine Electronics
Association (NMEA) and Radio Technical Commission for
Maritime Services (RTCM) communication standard for GPS
receivers, go to the following websites:

– www.nmea.org

– www.rtcm.org

On the Trimble website ((www.trimble.com), refer to the

document called NMEA-0183 Messages Guide for AgGPS
Receivers.

• 1 PPS output

To synchronize timing between external instruments and the
internal clock in the receiver, the connection port outputs a
strobe signal at 1 PPS (pulse per second). To output this signal,
the receiver must be tracking satellites and computing GPS
positions.

• J1939 (CAN) bus

Both connection ports on the receiver support the J1939
Controller Area Network (CAN) bus protocol. This protocol
standardizes the way multiple microprocessor-based electronic
control units (ECUs) communicate with each other over the
same pair of wires. It is used in off-highway machines, such as
those used in agriculture, construction, and forestry.

For more information, go to the Society of Automotive
Engineers (SAE) International website at

www.sae.org/servlets/index.

• ISO 11783 messages

Both CAN ports support some ISO 11783 messages.

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2 Overview

8 AgGPS 252 Receiver User Guide

Position output format

The AgGPS receiver outputs positions in Degrees, Minutes, and

Decimal Minutes (DDD°MM.m'). This is the NMEA standard format
and is commonly used worldwide for data transfer between electronic
equipment.

2.5 LED Indicator

The AgGPS 252 receiver has an LED light that shows the status of the

receiver. The following tables describe the light sequences for each
positioning method.

Note – WAAS/EGNOS and OmniSTAR VBS use the Satellite
Differential GPS positioning method.

Table 2.1 LED sequences with Satellite Differential GPS or Autonomous positioning

LED color LED flash Status

Off Off No power
Green Solid Normal operation: computing DGPS positions
Green Slow No DGPS corrections: computing DGPS positions using old

corrections

Green Fast No DGPS corrections approaching DGPS age limit: computing

DGPS positions using old corrections

Yellow Solid DGPS corrections being received but DGPS positions not yet being

computed: computing autonomous GPS positions
Yellow Slow No DGPS corrections: computing autonomous GPS positions
Yellow F ast Not enough GPS signals: not tracking enough satellites to compute

position

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AgGPS 252 Receiver User Guide 9

Overview 2

Table 2.2 LED sequences with RTK positioning

LED color LED flash Status

Off Off No power
Green Solid Normal operation: computing fixed RTK positions
Green Slow Receiving CMR corrections but not initialized: computing float RTK

positions
Green Fast No CMR corrections: computing RTK position using old corrections
Yellow Solid Receiving CMR corrections but unable to calculate RTK position:

computing DGPS (if WAAS/EGNOS is unavailable) or autonomous

position
Yellow Slow No CMR corrections: computing DGPS or autonomous position
Yellow Fast Not receiving CMR corrections: not computing positions

Table 2.3 LED sequences with OmniSTAR HP positioning

LED color LED flash Status

Off Off No power
Green Solid Normal operation: computing converged OmniSTAR HP positions
Green Slow Receiving OmniSTAR HP corrections, but only able to compute

unconverged position
Green Fast Receiving OmniSTAR HP corrections, but an HP error occurred
Yellow Solid Receiving OmniSTAR HP corrections but unable to calculate a

position: computing DGPS or autonomous solution
Yellow Slow No OmniSTAR HP corrections: computing DGPS or autonomous

position
Yellow Fast Not tracking OmniSTAR HP corrections: no positions

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2 Overview

10 AgGPS 252 Receiver User Guide

2.6 GPS Positioning Methods

GPS positioning systems are used in different ways to provide
different levels of accuracy. Accuracy is measured in absolute terms
(you know exactly where you are in a fixed reference frame).

Table 2.4 summarizes the GPS positioning methods. Imperial units in
this table are rounded to two decimal places. The values shown are
2sigma.

Table 2.4 Absolute accuracy of GPS positioning methods

For more information about each positioning method, see below.

26.1 RTK GPS positioning

The AgGPS 252 receiver uses the RTK positioning method to achieve

centimeter-level accuracy. To use the RTK method, you must first set
up a base station. The base station uses a radio link to broadcast RTK

corrections to one or more rover receivers. The AgGPS 252 receiver is

a rover receiver, so another compatible receiver, such as a Trimble

MS750™ or AgGPS 214 GPS receiver, must be used as the base

station.

GPS positioning
method

Corrections used Approximate absolute accuracy

Real-Time Kinematic
(RTK) GPS

Trimble CMR
corrections broadcast
by a local base station

2.5 cm (0.98 in) + 2 ppm horizontal
accuracy,

3.7 cm (1.46 in) + 2 ppm vertical accuracy
Satellite Differential GPS OmniSTAR VBS 78 cm (30.71 in)
Satellite Differential GPS WAAS/EGNOS 95 cm (37.40 in)
OmniSTAR HP

Differential GPS

OmniSTAR HP 10 cm (3.94 in) after the signal has fully

converged

1

1

Convergence time can vary, depending on the environment. Time to the first fix (submeter accuracy) is typically

<30 seconds; time to the first high accuracy fix (<10 cm accuracy) is typically <30 minutes.

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AgGPS 252 Receiver User Guide 11

Overview 2

The rover receiver uses RTK corrections from the base station to
calculate its position to centimeter-level accuracy. As part of this
process, the rover receiver must calculate an initialization. This takes a
few seconds. While the receiver is initializing, an RTK Float solution
is generated. Once initialized, an RTK Fixed solution is generated. It is
the RTK Fixed solution that provides centimeter-level accuracy.

The parts per million (ppm) error is dependent on the distance
(baseline length) between the base and rover receiver. For example, if
the distance is 10 km, a 2 ppm error equals 20 mm.

For more information about RTK positioning, go to the Trimble
website at www.trimble.com/gps/

26.2 Differential GPS positioning (DGPS)

For differential positioning, the AgGPS 252 receiver uses corrections

from WAAS/EGNOS satellites or from OmniSTAR VBS or HP
satellites.

These differential systems use special algorithms to provide
differential corrections that allow the rover receiver to calculate its
position more accurately.

Free corrections

WAAS/EGNOS corrections are free in North America and Europe.
For more information about WAAS, go to the Federal Aviation
Administration website at

http://gps.faa.gov/Programs/WAAS/waas.htm.

For more information about EGNOS, go to the European Space
Agency website at

www.esa.int/export/esaSA/GGG63950NDC_navigation_0.html.

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2 Overview

12 AgGPS 252 Receiver User Guide

Subscription-based corrections

The AgGPS 252 receiver uses OmniSTAR HP or OmniSTAR VBS

differential corrections in the same way that it uses WAAS/EGNOS
corrections.

OmniSTAR corrections are provided on a subscription basis.

The corrections that are produced by OmniSTAR HP algorithms are
more accurate than the corrections that are produced by OmniSTAR
VBS algorithms. The accuracy of the positions reported using
OmniSTAR HP increases with the time that has elapsed since the

instrument was turned on. This process is called convergence.

Convergence to where the error is estimated to be below 30 cm
(approximate 12 inches) typically takes around 20 minutes. Factors
that influence the time to convergence include the environment, the
geographical location, and the distance to the closest OmniSTAR
corrections base station. OmniSTAR is continually improving the
service.

For more information about OmniSTAR, go to the OmniSTAR
website at www.omnistar.com. For information about activating an
OmniSTAR subscription, see OmniSTAR, page 31.

26.3 Autonomous GPS positioning

Autonomous GPS positioning uses no corrections. The rover receiver
calculates its position using only the GPS signals it receives. This
method does not have high absolute accuracy, but the relative
accuracy is comparable to the other methods.

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AgGPS 252 Receiver User Guide 13

Overview 2

2.7 Sources of Error in GPS Positioning

The GPS positioning method influences the accuracy of the GPS

position that is output by the AgGPS 252 receiver. The factors

described in Table 2.5 also affect GPS accuracy.

Table 2.5 Factors that influence the accuracy of GPS positions

Condition Optimum

value

Description

Atmospheric
effects

GPS signals are degraded as they travel through the
ionosphere. The error introduced is in the range of 10 meters.

The error is removed by using a differential or RTK positioning
method.

Number of
satellites used

> 5 To calculate a 3D position (latitude and longitude, altitude, and

time), four or more satellites must be visible. To calculate a 2D
position (latitude and longitude, and time), three or more
satellites must be visible. For R TK positioning, five satellites are
needed for initialization. Once initialized, four or more satellites
provide RTK positions. The number of visible satellites
constantly changes and is typically in the range 5 through 9.
The AgGPS receiver can track up to 12 satellites
simultaneously.

Note – To see when the maximum number of GPS satellites are
available, use the Trimble Planning software and a current
ephemeris (satellite history) file. Both files are available free from
the Trimble website at www.trimble.com.

Maximum PDOP < 4 Position Dilution of Precision (PDOP) is a unitless, computed

measurement of the geometry of satellites above the current
location of the receiver. A low PDOP means that the positioning
of satellites in the sky is good, and therefore good positional
accuracy is obtained.

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2 Overview

14 AgGPS 252 Receiver User Guide

Signal-to-noise
ratio

> 6 Signal-to-noise ratio (SNR) is a measure of the signal strength

against electrical background noise. A high SNR gives better
accuracy.

Normal values are:

•GPS 6

• WAAS 3+

• OmniSTAR HP/VBS 6+

Minimum
elevation

> 10 Satellites that are low on the horizon typically produce weak

and noisy signals and are more difficult for the receiver to track.
Satellites below the minimum elevation angle are not tracked.

Multipath
environment

Low Multipath errors are caused when GPS signals are reflected off

nearby objects and reach the receiver by two or more different
paths. The receiver incorporates the EVEREST multipath
rejection option.

RTCM­compatible
corrections

These corrections are broadcast from a Trimble AgGPS 214,
MS750, or equivalent reference station.

RTK Base station
coordinate
accuracy

For RTK positioning, it is important to know the base station
coordinates accurately. Any error in the position of the base
station affects the position of the rover; every 10 m of error in a
base station coordinate can introduce up to 1 ppm scale error
on every measured baseline. For example, an error of 10 m in
the base station position produces an error of 10 mm over a
10 km baseline to the rover.

For more information about how to make sure the position of
your base station is accurate, refer to the manual for your base
station receiver.

Multiple RTK
base stations

If you are using several base stations to provide RTK
corrections to a large site area, all base stations must be
coordinated relative to one another. If they are not, the absolute
positions at the rover will be in error. F or more inf ormation about
how to use several base stations to cover your site , contact your
local Trimble Reseller.

Table 2.5 Factors that influence the accuracy of GPS positions (continued)

Condition Optimum

value

Description

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AgGPS 252 Receiver User Guide 15

Overview 2

27.1 Coordinate systems

Geographic data obtained from different sources must be referenced to
the same datum, ellipsoid, and coordinate format. Different formats
provide different coordinate values for any geographic location. In
North America, the datums NAD-27 and NAD-83 are commonly used
in Agricultural mapping applications.

The AgGPS 252 receiver outputs position coordinates in several

datums and ellipsoids depending on the GPS positioning method
being used. See Table 2.6.

For more information, go to the National Geodetic Survey website at

www.ngs.noaa.gov/faq.shtml#WhatDatum

Table 2.6 DGPS coordinate systems

GPS positioning method Datum Ellipsoid

None – Autonomous mode WGS-84

1

WGS-84

OmniSTAR VBS North American Beams NAD-83

2

GRS-80

OmniSTAR VBS Rest of World Beams ITRF

3

GRS-80
OmniSTAR HP ITRF 2000 ITRF 2000
WAAS Beams WGS-84 WGS-84
RTK WGS-84 WGS-84

1

World Geodetic System (WGS) 1984. Datum and ellipsoid.

2

North American Datum (NAD) 1983. Equivalent to WGS-84 in North America.

3

International Terrestrial Reference Frame (ITRF). Contact the DGPS provider for details.

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2 Overview

16 AgGPS 252 Receiver User Guide

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CHAPTER

3

AgGPS 252 Receiver User Guide 17

Installing the Receiver 3

In this chapter:

 Introduction
 System Components
 Mounting the Receiver
 Connecting to an External Device
 Connectors and Pinouts

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3 Installing the Receiver

18 AgGPS 252 Receiver User Guide

3.1 Introduction

This chapter describes how to check the equipment that you have
received, set up the receiver, and connect the receiver to another
device.

3.2 System Components

Check that you have received all components for the AgGPS system

that you have purchased. If any containers or components are
damaged, immediately notify the shipping carrier. Components are
listed in the following tables.

32.1 Optional extra

You may also have ordered the following item:

Table 3.1 AgGPS 252 receiver (P/N 55500-XX)

Quantity Description

1 AgGPS 252 DGPS receiver (P/N 55500-01)
1 System level cable (P/N 50165 or 50166)
1 Mounting plate assembly (P/N 51312-00)
1 Port B plug (P/N 51062)
1 AgGPS 252 Receiver User Guide

(this manual, P/N 55510-00-ENG)
1 Warranty Activation Card (P/N 25110-00)
1 OmniSTAR Activation Card (P/N 33965)

Table 3.2 Receiver option

Quantity Description

1 RTK capability (P/N 51264)

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AgGPS 252 Receiver User Guide 19

Installing the Receiver 3

3.3 Mounting the Receiver

Secure the AgGPS 252 receiver directly to the mounting plate

assembly (P/N 51312-00) and insert three bolts through the holes that
are in the housing and in the mounting plate assembly. Torque the
bolts to 75–80 inch pounds.

C

Warning – For continued protection against the risk of fire, the power
source (lead) to the model AgGPS 252 receiver should be pro vided with a
10 A (maximum) fuse.

33.1 Choosing a location

When choosing a location, consider the following:

Mount the receiver:

• on a flat surface along the centerline of the vehicle

• in any convenient location that is within 5.5 meters (18 ft) of
the port on the external instrument; if necessary, use the
optional extension cable to connect the receiver and external
device

Note – If you are using a Trimble AgGPS Autopilot system,
please refer to the installation instructions that are provided
with the Autopilot.

• at the highest point on the vehicle, with no metal surfaces
blocking the receiver’s view of the sky

• in such a way that it is not damaged when you drive the
machine into a shed or storage area

Do not mount the receiver:

• close to stays, electrical cables, metal masts, CB radio antennas,
cellular phone antennas, air-conditioning units (machine cab
blower fan), or machine accessory lights

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3 Installing the Receiver

20 AgGPS 252 Receiver User Guide

• near transmitting antennas, radar arrays, or satellite
communication equipment

• near areas that experience high vibration, excessive heat,
electrical interference, and strong magnetic fields

Note – A metal combine grain tank extension can block
satellites.

33.2 Environmental conditions

Although the receiver has a waterproof housing, you should install it
in a dry location. To improve the performance and long-term
reliability of the receiver, avoid exposure to extreme environmental
conditions, including:

• water

• excessive heat (> 70 °C or 158 °F)

• excessive cold (< –30 °C or –22 °F)

• high vibration

• corrosive fluids and gases

33.3 Electrical interference

As far as possible, when you install the receiver, you should avoid
placing it near sources of electrical and magnetic noise, such as:

• gasoline engines (spark plugs)

• computer monitor screens

• alternators, generators, or magnetos

• electric motors (blower fans)

• equipment with DC-to-AC converters

• switching power supplies

• radio speakers

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AgGPS 252 Receiver User Guide 21

Installing the Receiver 3

• high-voltage power lines

• CB radio antennas

• cellular phone antennas

• machine accessory lights

3.4 Connecting to an External Device

After installing the receiver and connecting the appropriate cabling,
you can connect the receiver to various external devices. For example:

To convert the AgGPS 252 receiver to a Trimble 12-pin conxall cable,

use the adapter cable (P/N 50581).

Note – Do not bend the cable at the Deutsch connector. When you
secure the cable, use the supplied P-Clip. The P-Clip provides
additional support to the connectors and reduces the risk of damage.

To connect the AgGPS 252
receiver to ...

use the cable ...

an Autopilot system P/N 50165

(this cable has no DB9 connector)
a Field computer P/N 50166
a Yield monitor P/N 50166
a Trimble SiteNet™ radio, for RTK

positioning

P/N 49801

Plug the ... into ...

Deutsch 12-pin connector Port A on the back of the receiver
straight DB9-pin connector the external device
power connectors a power supply

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3 Installing the Receiver

22 AgGPS 252 Receiver User Guide

Figure 3.1 shows how to connect the receiver to an external device
using the system level cable (P/N 50166).

Figure 3.1 Standard power/data cable connections

AgGPS 252 receiver

AgGPS 252 receiver

DB9

cable (P/N 50166)

Ground –ve

Power +ve

Deutsch 12-pin

LED indicator

Port A Port B

System level

To external
device

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AgGPS 252 Receiver User Guide 23

Installing the Receiver 3

When routing the cable from the receiver to the external device, avoid:

• sharp objects

• kinks in the cable

• hot surfaces (exhaust manifolds or stacks)

• rotating or moving machinery parts

• sharp or abrasive surfaces

• door and window jams

• corrosive fluids or gases

Note – Do not bend the cable at the Deutsch connector. When you
secure the cable, use the supplied P-Clip. The P-Clip provides
additional support to the connectors and reduces the risk of damage.

When the cable is safely routed and connected to the receiver, use
tie-wraps to secure it at several points, particularly near the base of the
receiver, to prevent straining the connection. Coil any slack cable,
secure it with a tie-wrap, and tuck it into a safe place.

The external device may have to be configured to work with the

AgGPS 252 receiver. The configuration tools for the external device

should be provided with the device. For more information about
configuring the receiver, see Chapter 4. For information about
connecting a particular external device, refer to the manual for that
device or contact your local Trimble Reseller.

Note – Use a connector plug (P/N 51062) to cover Port B when that
port is not in use. For example, cover Port B when you are using the
receiver in a non-RTK mode.

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3 Installing the Receiver

24 AgGPS 252 Receiver User Guide

3.5 Connectors and Pinouts

Use the following pinout information if you need to wire a cable for

use with the AgGPS 252 receiver.

Figure 3.2 AgGPS 252 receiver port pinout

213456

789101112

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AgGPS 252 Receiver User Guide 25

Installing the Receiver 3

35.1 Port A

Port A on the receiver has a 12-pin Deutsch DTM connector. For
cables, use the mating connector, Deutsch part number DTM06-12SA.

Viewed from outside the receiver, the Port A connector is on the left. It
is the port that is typically used to connect to an Autopilot system.

Ta ble 3.3 Port A pinout

Pin Name/Function Comments

1 CAN A High I/O
2 Port 1 RS232 Tx OUT When held to ground during power up,

puts unit into Monitor mode
3 Port 1 RS232 Rx IN
4 PPS OUT
5 Signal GND Used for RS232 and other signals.

Should not be connected to

V– (battery negative)
6 Port 1 RTS OUT
7 Event OUT / Alarm OUT
8 Port 1 CTS IN
9 Event IN
10 V+ IN
11 V- IN
12 CAN A Low I/O

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3 Installing the Receiver

26 AgGPS 252 Receiver User Guide

35.2 Port B

This port has the same connector as Port A, see above. Viewed from
outside the receiver, the Port B connector is on the right. It is the port
that is typically used to connect to the SiteNet 900 radio.

Ta ble 3.4 Port B pinout

Pin Name/Function Comments

1 CAN B High I/O
2 Port 2 RS232 Tx OUT
3 Port 2 RS232 Rx IN
4 PPS OUT
5 Signal GND Used for RS232 and other signals.

Should not be connected to V–
(battery negative)

6 Port 2 RTS OUT

or Port 3 RS232 Tx OUT
7 Event OUT / Alarm OUT
8 Port 2 CTS IN or Port 3

RS232 Rx IN
9Event IN
10 V+ IN / OUT Maximum output current = 1.25 A
11 V– IN / OUT Maximum output current = 1.25 A
12 CAN B Low I/O

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CHAPTER

4

AgGPS 252 Receiver User Guide 27

Configuring the Receiver 4

In this chapter:

 Introduction
 AgRemote Home Screen
 Configuring Differential GPS
 Configuring the AgGPS 252 Receiver to Operate in RTK Mode
 Configuring the Communication Ports

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4 Configuring the Receiver

28 AgGPS 252 Receiver User Guide

4.1 Introduction

Use either the Autopilot interface or the Trimble AgRemote utility to

change configuration settings in the AgGPS 252 receiver. You will

need to configure the receiver if you connect to a third-party device,
for example.

•If a Trimble AgGPS Autopilot system is configured to use an
AgGPS 252 receiver, and the port on the receiver is set to

8-N-1 38.4 K, the Autopilot system automatically configures
the receiver.

• The AgRemote utility is available from the Trimble website
(www.trimble.com). This chapter describes how to use the
utility to perform some common configurations.

Note – OmniSTAR VBS and HP are subscriber services that need to be
activated. For more information, see OmniSTAR, page 31.

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AgGPS 252 Receiver User Guide 29

Configuring the Receiver 4

4.2 AgRemote Home Screen

Figure 4.1 shows the AgRemote Home screen when WAAS

corrections are being received.

Figure 4.1 AgRemote Home screen

For more information about these fields and how they change as you

change GPS mode, refer to the document called AgRemote Software

on the Trimble website (www.trimble.com) or contact your local
Trimble Reseller.

D/3D í07 DOP03
WAAS 122 ÷ø04

Correction type

DGPS satellite name or ID

Signal-to-Noise ratio
of DGPS satellite

Current PDOP value

Position type

Number of GPS satellites being tracked

GPS indicators
Correction

indicators

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4 Configuring the Receiver

30 AgGPS 252 Receiver User Guide

4.3 Configuring Differential GPS

For the receiver to output GPS position coordinates of submeter
accuracy, you must first select a differential signal from one of the
following sources:

• WAAS/EGNOS – free service, limited availability

The Wide Area Augmentation System (WAAS) augments GPS
with additional signals for increasing the reliability, integrity,
accuracy, and availability of GPS in the United States. The
European Geostationary Navigation Overlay System (EGNOS)
is the European equivalent of WAAS.

• OmniSTAR – paid subscription, available worldwide

You can use this paid service as an alternative to
WAAS/EGNOS. It provides over-the-air DGPS activation.

For more information, see Differential GPS positioning (DGPS),
page 11.

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AgGPS 252 Receiver User Guide 31

Configuring the Receiver 4

43.1 OmniSTAR

The AgGPS 252 receiver can use OmniSTAR corrections. To do this,

you need to configure the receiver and purchase an OmniSTAR
subscription.

Note – To track the OmniSTAR satellite, the receiver must be outside
with a clear view of the sky, turned on, and configured to receive
OmniSTAR VBS or HP corrections.

To use the AgRemote utility to activate an OmniSTAR subscription:

1. Connect the AgGPS 252 receiver to the computer. Turn on the

receiver and start the AgRemote utility. For instructions on how
to use AgRemote, refer to the AgRemote documentation.

2. In AgRemote, select Configuration / DGPS Config.

3. Set the Source Select field to one of the following:

– Omnistar HP

– Omnistar VBS

4. Set the EZ Sat: Omni* field to the area you are operating in. For

example, if you are working in California, select N. America
West.

5. Press 4 then 5 to complete the procedure.

6. Obtain an OmniSTAR licence from OmniSTAR. All licenses
are activated over the air. Contact OmniSTAR on
1-888-883-8476 (USA or Canada) and provide the following
details:

– your billing information

– serial number

– satellite beam name

OmniSTAR will activate the receiver. Activation can take
5–30 minutes.

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4 Configuring the Receiver

32 AgGPS 252 Receiver User Guide

40.1W AAS/EGNOS

WAAS is a free satellite-based DGPS service that is available only in
North America; EGNOS is a free satellite-based DGPS service that is
available only in Europe.

To use the WAAS/EGNOS DGPS signal, you must first configure the
receiver.

1. Connect the AgGPS 252 receiver to the computer. Turn on the

receiver and start the AgRemote utility.

2. In AgRemote, select Configuration / DGPS Config.

3. Set the Source Select field to WAAS.

4. Press 4 then 5 to complete the procedure.

To enable WAAS reception in the field:

1. Take the receiver outside. Make sure that it has a clear southeast
and southwest view of the sky.

2. Turn on the receiver. WAAS activation can take two or more

minutes. Once activation succeeds, the Home screen displays

D/3D.

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AgGPS 252 Receiver User Guide 33

Configuring the Receiver 4

4.1 Configuring the AgGPS 252 Receiver to Operate in

RTK Mode

Use the AgRemote utility to configure the AgGPS 252 receiver for

operation in RTK mode. To configure the receiver:

1. Connect the AgGPS 252 receiver to the computer. Turn on the

receiver and start the AgRemote utility.

2. In AgRemote, select Configuration / DGPS Config.

3. Set the Source Select field to RTK.

4. Press 4 then 5

to complete this part of the procedure.

5. For RTK operation, connect the radio to a port. Change the port
input settings for that port to RtkLnk.

4.1 Configuring the Communication Ports

If the AgGPS 252 receiver is to be connected to an external device,

configure Ports A and B so that the proper data type is input to and
output from the receiver.

To configure Port A:

1. Connect the AgGPS 252 receiver to the computer. Turn on the

receiver and start the AgRemote utility.

2. In AgRemote, select Configuration / Port A Config.

3. Use the menu commands to configure the communication ports.
Ensure that the receiver outputs the correct GPS position data
type for the hardware device or software program that is
connected to the receiver.

To configure Port B:

• Repeat the above steps but in Step 2 select Configuration / Port
B Config.

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4 Configuring the Receiver

34 AgGPS 252 Receiver User Guide

40.1 Configuring input/output communication

The port input and output settings appear in the first screen. In
Figure 4.2, the port is set to accept TSIP inputs at a baud rate of
115,000 with a parity of 8-Odd-1. The outputs are TSIP, also at a baud
rate of 115,000.

Figure 4.2 Communication settings

Configure the Port Input/Output communication settings for

communicating with the AgGPS Autopilot, other external hardware

devices, and software programs. Table 4.1 describes the input settings.

Ta ble 4.1 Port input settings

Setting Description

None Inputs nothing to the receiver.
TEXTB The receiver can accept ASCII data from an external device,

such as a chlorophyll meter, on Port A, merge it with NMEA GPS
data, and output the combined data on Port B. The incoming data
must be limited to 66 ASCII characters and terminated by a
carriage return and line feed (hex characters 0x0D 0x0A). The
NMEA string outputs as $PTNLAG001,<up to 66 ASCII
characters>*<2 digit checksum><CR><LF>. For the receiver to
output the combined NMEA string, NMEA must be selected as
the output protocol on Port B.

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AgGPS 252 Receiver User Guide 35

Configuring the Receiver 4

The default port settings are:

Note – The AgRemote utility, when connected to an AgGPS 252
receiver, automatically resets the receiver port communication settings
to 8-O-1 TSIP 115 K. This enables optimal communication with an
office computer. If the receiver is to work with an Autopilot system,
however, the receiver port communication settings must be 8-N-1 TSIP

38.4 K. To work with some other devices and software programs, the
receiver port communication settings must be 8-N-1 NMEA 4800. If
AgRemote has changed the settings, you will need to change them
back manually.

TEXTA See the description for the TEXTB setting (above). TEXTA input

outputs text on Port A. The default port settings are 8-N-1 TSIP

38.4 K. These may vary by product.

RTCM The receiver can accept RTCM data from an external DGPS

device, such as an external radio.

TSIP The receiver can accept or output TSIP data packets from the

port when using the optional AgRemote program or using the
AgGPS 170 Field Computer.

RtkLnk The receiver can accept real-time corrections (CMR data) from

an external device such as a Trimble radio.

Port A Port B

Baud rate In TSIP 38,400 TSIP 38,400

Out TSIP 38,400 TSIP 38,400
Data bits 88
Parity None None
Stop bits 11

Table 4.1 Port input settings (continued)

Setting Description

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4 Configuring the Receiver

36 AgGPS 252 Receiver User Guide

When using a Trimble SiteNet 900 radio, make sure that the
communication settings are correct in the receiver.

The default settings to use with the SiteNet radio are:

Changing the input or output port settings

1. From the Port A Config screen, press 2 until the Port-A
Input/Output screen appears:

2. Press 3 to activate the cursor.

3. Press 1 or 2 to change the value.

4. Press 3.

5. Repeat Steps 3 and 4 until you have set all the required values.

6. Press 4 to save all the changes.

7. Press 2 to move to the next screen.

Setting Description

Baud rate 38,400
Data bits 8
Parity None
Stop bits 1

åæ I RTCM 9600
8N1 0 NMEA 4800

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AgGPS 252 Receiver User Guide 37

Configuring the Receiver 4

NMEA settings

Three screens (NMEA1, NMEA2, and NMEA3) show what NMEA
messages are output from the port. Message types shown in upper case
are being output; message types shown in lower case are not.

For more information about NMEA message types, refer to the

document called NMEA-0183 Messages Guide for AgGPS Receivers

on the Trimble website (www.trimble.com).

Port output rate

This setting can be used to vary the NMEA and TSIP output rate. A
setting of 1 outputs one position each second.

ASAP equals the rate selected on the Filter and Position Rate screen
under the GPS Config menu. A setting of ASAP outputs positions five

or ten times every second. The default (factory) setting is 1 Hz.

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4 Configuring the Receiver

38 AgGPS 252 Receiver User Guide

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CHAPTER

5

AgGPS 252 Receiver User Guide 39

Troubleshooting 5

In this chapter:

 Introduction
 Problems and Solutions
 Troubleshooting Flowcharts

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5 Troubleshooting

40 AgGPS 252 Receiver User Guide

5.1 Introduction

This chapter describes some problems that can arise and explains how
to solve them. It includes a series of flowcharts to help with
troubleshooting.

As you work through this chapter, you may need to view the receiver
status or change values in some fields. For information on how to do

this, refer to the document called NMEA-0183 Messages Guide for
AgGPS Receivers. This document is on the Trimble website

(www.trimble.com).

5.2 Problems and Solutions

Should problems arise, try the following solutions.

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AgGPS 252 Receiver User Guide 41

Troubleshooting 5

Global Positioning System (GPS)

Problem Possible solution
Poor accuracy

The accuracy of GPS positions is
poor because the receiver is picking
up poor quality signals from the
satellites.

The receiver always calculates the
most accurate position it can, given
the current GPS satellite differential
operating conditions.

Change some or all of the following GPS settings:

• Minimum elevation – Increase the setting
(the default is 8°).

• Minimum Signal Strength – Increase the System
Mask AMU setting (the default is 3).

• Maximum PDOP – Decrease the setting
(the default is 13).

• GPS Mode – Change to Manual 3D
(the default is Auto 2D/3D).

• DGPS Mode – Change to DGPS
(the default is DGPS Auto/On/Off).

GPS signals are reflecting off nearby
trees and/or metal buildings and
horizontal surfaces.

To reduce multipath noise, mount the GPS receiver
so that it has a clear view of the sky. The receiver
must be away from trees and large metal objects.

Intermittent loss of lock on
satellite

The receiver loses the satellite
signal from time to time.

Make sure that the receiver is mounted on the
highest point of the vehicle and is clear of metal
surfaces.

Check Maximum PDOP and Minimum Signal
Strength settings (see Poor accuracy, above).

Intermittent DGPS signal

The correction signal strength can
drop to unusable levels. Causes
include tree canopy cover between
the receiver and the differential
satellite, radar sets, and microwave
transmitters.

Move the receiver away from the tree cover and/or
from sources of electromagnetic interference.

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5 Troubleshooting

42 AgGPS 252 Receiver User Guide

Tracking but not receiving a
differential signal

The receiver is tracking satellites
and tracking an OmniSTAR satellite
beam, but is not receiving DGPS
signals. The Home screen indicates
how many satellites are being
tracked, and whether a differential
source is being tracked.

You see :
h-3D for HP not converged
H-3D for HP converged
r-3D for RTK float
R-3D for RTK fixed
D-3D for DGPS

HP and RTK also give an indication
of positional accuracy on the Home
screen (AgRemote).

Check that your DGPS service subscription is still
current and enabled.

For OmniSTAR service:

1. Use the AgRemote utility to navigate to one of the
following screens, depending on what you are
using:

•the Omni HP Info screen

•the Omni VBS Info screen.

2. Press

4 until Stop Date appears.

If the message Access Unknown appears, contact
OmniSTAR to reactivate your subscription. F or more
information, see OmniSTAR, page 31.

The receiver must be switched on and configured to
track the correct satellite coverage beam before it
can be reactivated.

The receiver automatically tracks the correct beam
based on receiver geographic location. If the
receiver is manually changed, automatic tracking is
deactivated until you perform a hard reset or
firmware flash.

When a satellite subscription is activated, the Home
screen displays D/3D .

Problem Possible solution

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AgGPS 252 Receiver User Guide 43

Troubleshooting 5

No GPS position output from the
receiver after connecting to
AgRemote

When the receiver is connected to
the AgRemote utility, AgRemote
automatically resets the port
communication settings on the
receiver to 8-O-1 TSIP 115 K for
both input and output. This enables
optimal communication with an office
computer.

If the receiver is to work with an
Autopilot system, however, the
receiver port communication settings
must be 8-N-1 TSIP 38.4 K. To work
with some other devices and
software programs, the receiver port
communication settings must be
8-N-1 NMEA 4800. If AgRemote has
changed the settings, you will need
to change them back manually.

Connect AgRemote. Then reset the port
communication settings to NMEA output. For more
information, see Configuring the Communication
Ports, page 33.

Long time to initialize

In RTK mode, longer baselines
require longer initialization times.
(The baseline is the distance
between the base receiver and the
rover receivers.)

Wait for the receiv er to initialize or consider
repositioning the base receiver to shorten the
baseline. Make sure the rover is in a clear area.

Loss of initialization

In RTK mode initialization can be
lost when the rover receiver is close
to trees or buildings and the number
of satellites falls below four.
Additionally, initialization may be lost
if the receiver has not been tracking
RTK corrections for some time. For
more information, see the next item.

Move away from trees and obstructions to initialize.
Once initialized, approach the obstructed area again.
If the obstructions are severe, GPS positioning may
not work in that area.

Because the GPS satellites move, there may be
times of the day when you are working in an area
with obstructions. For more information, see the
Trimble Planning software on the Trimble website
(www.trimble.com).

Problem Possible solution

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5 Troubleshooting

44 AgGPS 252 Receiver User Guide

Interference

Not tracking RTK corrections

The radio link is down or intermittent. • Ensure that the line-of-sight between the base

and rover receivers is not obstructed.

• Ensure that the rover receiver is within range of
the radio.

• Ensure that the radio power supply is on.

Problem Possible solution
Strong magnetic fields

Strong magnetic fields have no
effect on GPS or satellite DGPS
signals.

However , some computers and other
electric equipment radiate
electromagnetic energy that can
interfere with a GPS receiver.

If you suspect interference from a local magnetic
field, move the receiver away from, or turn off, the
suspect electronics while observing the number of
satellites being tracked on the receiver or the signal­to-noise ratio (SNR) of the satellite. If the SNR goes
up when the electronics are turned off, there may be
interference from the local electronics.

FM 2-way radios

Transmitting FM 2-way radios can
interfere with OmniSTAR, WAAS,
and GPS signal reception.

Make sure that there is at least 1 m (3 ft) between
the FM 2-way radio antenna and the receiver.

Engine noise

An unshielded ignition system can
cause enough noise to block
reception of a differential signal.

Use resistor spark plug wires on the vehicle ignition
system.

Problem Possible solution

Ag252_100A_UserGde_ENG.book Page 44 Wednesday, January 28, 2004 5:42 PM

AgGPS 252 Receiver User Guide 45

Troubleshooting 5

GPS receiver

An alternator can cause noise that
interferes with a differential signal.

Use bypass capacitors, commonly available in
automotive stores for cleaning up interference to CB
and other radios. If the problem persists, shield
engine components with aluminum foil.

Relocate the antenna on the machine.
Determine the optimal antenna location by watching

the SNR value on the AgRemote Home screen.

Note – Before replacing engine parts in an attempt
to solve this problem, make sure that the problem is
not caused by a computer or power source near the
receiver. Some computers and their power sources
cause noise that disrupts GPS and satellite DGPS
signals.

Problem Possible solution
Mounting location

The receiver is not picking up a clear
signal.

Mount the receiver on the centerline of the vehicle,
away from any sources of interference and with a
clear view of the sky (see Choosing a location,
page 19).

Cables

One of the cables seems faulty . Use an ohmmeter to check the cable. The resistance

of a good cable between connector pins at each end
of the cable is zero.

If the cable is sound, but the problem persists, try
exchanging the cable with one that you know is
working.

If the cable is defective, contact your local Trimble
Reseller for an RMA number (if the Trimble product
is still under warranty), or to purchase a replacement
cable.

Problem Possible solution

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5 Troubleshooting

46 AgGPS 252 Receiver User Guide

AgRemote utility

Real-time clock battery

A lithium-ion battery in the receiver
powers the internal real-time clock
and so enables the receiver to get a
first fix faster. The battery has a life
of 7.5 years. When th e battery fails,
the internal clock cannot keep
accurate time and the receiver may
take longer to output GPS positions.

Please contact your local Trimble Reseller to get
the batteries replaced. You cannot replace the
battery yourself.

Factory defaults

You ne ed to restore the receiver
factory defaults.

To restore receiver factory default settings:

1. Conne ct the receiver to a computer. Turn on the
receiver.

2. Run th e AgRemote utility.

3. Navigate to the Clear BB RAM screen.

4. Press

2 until Yes appears.

5. Press 4.

The factory default settings are restored. The DGPS
service subscription is not lost.

Problem Possible solution

AgRemote cannot communicate with
the receiver. All you see is a blank
screen.

1. Make sure that:

• the receiver is connected to a 12–32 V DC power
source

• all cable connections between the receiver and
the computer are secure

• you are using the correct COM port

2. Turn off the receiver then turn it on again.

3. Select File / Connect.

Problem Possible solution

Ag252_100A_UserGde_ENG.book Page 46 Wednesday, January 28, 2004 5:42 PM

AgGPS 252 Receiver User Guide 47

Troubleshooting 5

FlashLoader 200 upgrade utility

Problem Possible solution

The FlashLoader 200 upgrade utility
cannot detect the receiver or
download the firmware.

Make sure that:

• Other programs, such as AgRemote and
Microsoft® ActiveSync® technology , are not using
the COM port that the computer is using.

• The receiver is connected to a 12–32 V DC
power source.

• All cables are connected correctly between the
device and the computer.

• The receiver is connected to the correct computer
COM port. To do this:

1. From the FlashLoader 200 menu, select
Settings.

2. Select the check box for a serial link.

3. At Port, select Auto. Click OK.

4. Select the Upload firmware to receiver check
box.

5. Navigate to where the firmware file is saved
and select the file. Click Proceed.

6. From the Auto Port Select dialog, select Use
receiver on port... and click OK.

Once you have checked this, turn off the receiver
then turn it on again. Try again to connect
FlashLoader 200.

Ag252_100A_UserGde_ENG.book Page 47 Wednesday, January 28, 2004 5:42 PM

5 Troubleshooting

48 AgGPS 252 Receiver User Guide

5.1 Troub leshooting Flowcharts

These flowcharts describe how to troubleshoot problems in the
following areas:

• system hardware and power

• GPS reception (no third-party device attached)

• GPS reception (third-party device attached)

• OmniSTAR positioning

• RTK (using the AgRemote utility)

In addition, you may find it useful to review Chapter 3, Installing the
Receiver.

Ag252_100A_UserGde_ENG.book Page 48 Wednesday, January 28, 2004 5:42 PM

AgGPS 252 Receiver User Guide 49

Troubleshooting 5

Figure 5.1 Troubleshooting system hardware and power

START HERE

The receiver is connected

and has sufficient power

for operation.

Is the receiver LED

or AgRemote

screen on?

Is the data/power cable

securely connected to

the receiver antenna?

Connect the red and

black power leads of

the data/power cable to

machine 10-32 V DC

power.

Is the receiver or

AgRemote screen

light on?

Yes

Continue

No

No

Can you turn on

the machine

(combine or tractor)?

No

No

There may be a fault

with the machine

power. Contact your

local farm implement

dealer.

Yes

Recheck the

data/power cable

connections. If the

problem persists,

contact your local

Trimble Reseller.

Is the LED on?

No

The receiver has insufficient

power. Contact your local

Trimble Reseller.

Yes

Yes

Yes

Check the battery

power. Is the battery

voltage between

10-32 volts?

Yes

Ag252_100A_UserGde_ENG.book Page 49 Wednesday, January 28, 2004 5:42 PM

5 Troubleshooting

50 AgGPS 252 Receiver User Guide

Figure 5.2 Using AgRemote to troubleshoot GPS reception (no third-party device attached)

S

T

A

R

T

H

E

R

E

Yes

Yes

No

Continue

No

Yes

No

Is the AgRemote

screen on?

Check the Home

screen for GPS

reception. Is the

receiver tracking at

least 4 satellites?

Yes

Does the Home

screen display D/3D

(for a 3D position)?

Yes

The GPS reception

appears to be working

correctly. If the problem

persists, contact your

local Trimble Reseller.

See the system

hardware and power

flowchart. When GPS

satellite reception is

resolved. Return to this

flowchart.

No

Make sure that the

receiver/antenna is

located with a clear

view of the sky.

Are you receiving

satellites now?

No

See the OmniSTAR VBS or

RTK flowcharts.

If the problem persists,

contact your local

Trimble Reseller.

No

Restore GPS

default values.

Turn off the machine

engine (combine or tractor)

but maintain power to the

GPS receiver.

Return to the Home screen

and check GPS reception.

Is the receiver tracking at

least 4 satellites?

Return to the Home

screen and check

GPS reception.

Is the receiver

tracking at least 4

satellites?

No

Yes

Turn on the machine engine

and check the Home

screen. Do the satellites

disappear?

The GPS reception appears

to be working correctly. If

the problem persists,

contact your local Trimble

Reseller.

The problem is unresolved.

Contact your local Trimble

Reseller.

The problem may be

caused by excessive

engine noise.

For information on

reducing engine noise,

see Chapter 3.

If the problem persists,

contact your local

Trimble Reseller.

Yes

Ag252_100A_UserGde_ENG.book Page 50 Wednesday, January 28, 2004 5:42 PM

AgGPS 252 Receiver User Guide 51

Troubleshooting 5

Figure 5.3 Using AgRemote to troubleshoot GPS reception (third-party device attached)

S

T

A

R

T

H

E

R

E

Yes

Yes

Yes

No

Yes

No

No

No

Yes

No

Continue

Yes

Continue

Yes

No

No

Continue

No

No

Yes

Is the AgRemote

screen on?

Is the text visible on

the receiver or

AgRemote screen?

Check the Home screen

for GPS reception. Is the

receiver tracking at least

4 satellites?

If applicable, does the

device display DG

(for a 3D position)?

Make sure that the

cable is securely

connected from the

device to the receiver.

Your GPS reception

appears to be

working correctly. If

the problem persists,

contact your local

Trimble Reseller.

See the system

hardware and power

flowchart.

When the GPS

reception is resolved,

return to this flowchart.

Make sure that the

receiver/antenna is

located with a clear

view of the sky.

Is the receiver now

tracking at least

4 satellites?

Check that the receiver

is configured correctly

for input/output

communications.

Does the device

display DG?

Contact your local

Trimble Reseller.

Restore GPS

default values.

Return to the Home

screen and check

GPS reception.

Are you receiving at

least 4 satellites?

See the OmniSTAR VBS

or RTK flowchart.

If the problem persists,

contact your local Trimble

Reseller.

Does the receiver

Home screen

display D/3D?

The data/power cable

may be faulty. Contact

your local Trimble

Reseller.

Turn off the machine engine

(combine or tractor) but

maintain power to the GPS

receiver. Wait five minutes.

Return to the Home screen

and check GPS reception.

Is the receiver tracking at

least 4 satellites?

Turn on the machine engine

and check the Home

screen. Do the satellites

disappear?

Your GPS reception

appears to be working

correctly. If the problem

persists, contact your local

Trimble Reseller.

The problem

is unresolved.

Contact your local

Trimble Reseller.

The problem may be

caused by excessive

engine noise.

For information on

reducing engine noise,

see Chapter 3.

If the problem persists,

contact your local

Trimble Reseller.

Yes

Yes

No

Ag252_100A_UserGde_ENG.book Page 51 Wednesday, January 28, 2004 5:42 PM

5 Troubleshooting

52 AgGPS 252 Receiver User Guide

Figure 5.4 Using AgRemote to troubleshoot OmniSTAR positioning

S

T

A

R

T

H

E

R

E

Yes

No

No

Yes

Yes

No

Yes

Check the AgRemote

Home screen for GPS

reception. Is the

receiver tracking at

least 4 satellites?

Does the AgRemote

Home screen display

S for DGPS satellite

mode?

Make sure that your

OmniSTAR subscription

service is current,

activated, and correctly

configured.

If the problem

persists, contact

your local Trimble

Reseller.

Continue

No

No

See the GPS reception

flowchart. When GPS

satellite reception is

resolved, return to this

flowchart.

Wait one minute.

Does the receiver or

AgRemote Home

screen now display

D/3D (3D position)?

The system appears

to be working

correctly. If the

problem persists,

contact your local

Trimble Reseller.

Check the Home

screen for satellite

signal strength. Is the

S/N (signal to noise

ratio) 6 or more?

Check the Omni* VBS

Info screen. Press 4. Is

OmniSTAR enabled?

Press 4 until you see

Stop and a date.

Has the date expired?

The OmniSTAR almanac

may be out of date. Set up

the receiver and track

satellites for 1-2 hours to

acquire a new almanac.

If the problem persists,

contact your local Trimble

Reseller.

Turn on the machine

engine and check the

Home screen. Do the

satellites disappear?

Something may be

interfering with the

OmniSTAR satellite signal.

Check the Age of DGPS /

Age of Synch screen. Is the

DGPS age 10 or more? Is

the Synch age 3 or less?

Press 4 again to check

OmniSTAR status.

Do you see either of the

following messages?

Received Data

No Recent Data

Is the status message

one of the following?

Init Decoder (1-4)

Decoder Ready

Access Confirmed

The received or old data

is not sufficient for good

DGPS positioning.

Contact OmniSTAR.

Contact your local

Trimble Reseller.

Turn off the machine

engine (combine or tractor)

but maintain power to the

GPS receiver. Wait

five minutes.

Return to the Home screen

and check GPS reception.

Are you receiving at least

4 satellites?

The problem is unresolved.

Contact your local

Trimble Reseller.

The problem may be

caused by excessive

engine noise.

For information on reducing

engine noise,

see Chapter 3.

If the problem persists,

contact your local

Trimble Reseller.

The receiver is tracking

GPS satellites but not

receiving the OmniSTAR

signal. Contact your local

Trimble Reseller.

No

Continue

Yes

No

No

Yes

Yes

No

No

Yes

Yes

Yes

No

No / Not sure

Ag252_100A_UserGde_ENG.book Page 52 Wednesday, January 28, 2004 5:42 PM

AgGPS 252 Receiver User Guide 53

Troubleshooting 5

Figure 5.5 Using AgRemote to troubleshoot RTK

START HERE

Check that there are

no other base stations

operating in the area,

interfering with your

base station signal.

Check the AgRemote Home

screen for GPS reception. Is

the receiver tracking at least 4

satellites?

See the GPS Reception

Troubleshooting Guide.

When GPS satellite

reception is resolved, return

to this guide.

Move the roving receiver to a

place where there is a clear

line of sight between it and

the base station. Are RTK

corrections being received

now? Does the AgRemote

screen display r or R?

No

Check the power supply to

the base station and the base

radio. Is the base transmit

light on?

Provide power to the

base station and radio.

Check that the receiver is

initialized. Does the

AgRemote Home screen

display R for a fixed

solution?

Are 5 or more satellites

being tracked?

Yes

Move the receiver away from

any obstructions so that it

can track at least 5 satellites.

Receiver is operating

normally.

Receiver should initialize

soon (wthin 30 seconds for

baselines under 5 km). After

30 seconds does the Home

screen display R for a fixed

solution?

Something may be interfering

with the GPS signal. See the

GPS Reception Trouble-

Shooting Guide. Is the

problem still unresolved?

Continue

No

Yes

Check that the receiver is

receiving RTK corrections.

The age on Home screen

should be 1 if receiving

radio. Does the AgRemote

Home screen display r or R

for an RTK solution?

No

No

No

Yes

No

No

Yes

Check the Rover receiver

light to ensure RTK

corrections are present. Is the

LED flashing yellow?

No

No CMR corrections are being

received. In the Config screens

use RTK link to make sure that

the rover radio parameters are

the same as the base radio

parameters. Are CMR

corrections being recieved now?

Yes

No

Yes

Check the AgRemote screen

for RTK status and contact

your local Trimble Reseller.

Yes

Receiver is operating

normally.

Yes

Is the RTK option installed in

the receiver?

Yes

No

Obtain and install the RTK

option

Yes

Yes

Ag252_100A_UserGde_ENG.book Page 53 Wednesday, January 28, 2004 5:42 PM

5 Troubleshooting

54 AgGPS 252 Receiver User Guide

Ag252_100A_UserGde_ENG.book Page 54 Wednesday, January 28, 2004 5:42 PM

APPENDIX

A

AgGPS 252 Receiver User Guide 55

Specifications A

A.1

AgGPS 252 Receiver

Table A.1 lists the physical characteristics of the AgGPS 252

combined GPS/DGPS receiver and antenna.

Table A.1 AgGPS 252 receiver

Item Description

Size 300 mm (11.7 in) wide x 309 mm (12.05 in) deep x 70 mm

(2.73 in) high
Weight 2.1 kg
Power Nominal 350 mA at 12 V DC
Operating temperature –30 °C (–22 °F) through +70 °C (+158 °F)
Storage temperature –40 °C (–40 °F) through +85 °C (+185 °F)
Humidity Complies with Mil 810E Method 507.3 Procedure III Aggravated

Cyclic Humidity.

Ten 24 hour cycles of constant 95% RH, with cycling

temperature and dwells +30 °C (+86 °F) and +60 °C (140 °F).

Unit sealed to +/- 5 PSID
Casing Low-profile UV-resistant plastic. Dust-proof, waterproof, shock

resistant, with recessed protected connectors.

Ag252_100A_UserGde_ENG.book Page 55 Wednesday, January 28, 2004 5:42 PM

A Specifications

56 AgGPS 252 Receiver User Guide

A.2 GPS Channels

Table A.2 lists the performance characteristics of GPS channels.

Connectors 12-pin Deutsch connectors
Ports Two connection ports, both of which support RS-232 and CAN
Mounting Three holes for 10 mm (0.39 in) bolts
Compliance FCC Part 15 Class A, C-Tick, E-mark,

CE-mark

T ab l e A.2 GPS channels performance

Item Description

General 12-channel, parallel tracking L1 1571.42 MHz and L2

1227.60 MHz. C/A code and carrier phase filtered measurement.
Update rate 1, 5, 10 Hz
RTK speed accuracy 0.16 kph (0.10 mph)
RTK position accuracy Horizontal 2.5 cm (0.98 in) + 2 ppm, 2 sigma, and vertical 3.7 cm

(1.46 in) + 2 ppm, 2 sigma, if all of the following criteria are met:

• At least 5 satellites

•PDOP <4

• CMR corrections

• Standard format broadcast from a Trimble MS750, AgGPS 214,
or equivalent reference station

Differential speed
accuracy

0.16 kph (0.1 mph)

Table A.1 AgGPS 252 receiver (continued)

Ag252_100A_UserGde_ENG.book Page 56 Wednesday, January 28, 2004 5:42 PM

AgGPS 252 Receiver User Guide 57

Specifications A

Differential position
accuracy

Less than 1 m (3.28 ft) horizontal if all of the following criteria are
met:

• At least 5 satellites

•PDOP <4

• RTCM SC-104 corrections

• Standard format broadcast from a Trimble MS750, AgGPS 214,
or equivalent reference station

OmniSTAR HP speed
accuracy

0.16 kph (0.1 mph)

OmniSTAR HP position
accuracy

10 cm (3.94 in) after convergence, 2 sigma, if all the following
criteria are met:

• At least 5 satellites

•PDOP <4

• OmniSTAR HP corrections

Convergence time can vary, depending on the environment.
Time to the first fix (submeter accuracy) is typically
<30 seconds; time to the first useable fix (<10 cm accuracy) is

typically <30 minutes.
Time to first fix <30 seconds, typical
Multipath mitigation EVEREST technology
Satellite differential

compatibility

OmniSTAR, WAAS, and EGNOS

NMEA messages GGA 1 1

1

, GLL, GSA1, GST, GSV, GST, MSS, PTNLDG, PTNL
PJK, PTNL PJT, PTNL VGK, PTNL VHD, PTNLEV, PTNLID,
PTNLSM, RMC1, VGK, VTG1, XTE, ZDA

1

By default, the receiver is configured to output GCA, GSA, RMC, and VTG messages at a 1Hz (1 position per second)

update rate.

Table A.2 GPS channels performance (continued)

Ag252_100A_UserGde_ENG.book Page 57 Wednesday, January 28, 2004 5:42 PM

A Specifications

58 AgGPS 252 Receiver User Guide

A.3 L-Band Satellite Differential Correction Receiver

Table A.3 lists the characteristics of the L-band satellite differential
correction receiver with OmniSTAR support.

A.4 Receiver Default Settings

Table A.4 lists the receiver default settings.

Table A.3 L-Band satellite differential correction receiver with

OmniSTAR support

Item Description

Bit error rate 10

-5

for Eb/N of >5.5 dB
Acquisition and reacquisition time <5 seconds, typical
Frequency band 1525–1559 MHz
Channel spacing 0.5 kHz

Table A.4 Receiver default settings

Item Description

DGPS source WAAS/EGNOS
Dynamics Land
Minimum elevation 8°
AMU mask 3
PDOP mask 13
PDOP 2D/3D switch 11
DGPS mode Auto On/Off
DGPS correction age limit 250 seconds
Pos fix rate 1 Hz

Ag252_100A_UserGde_ENG.book Page 58 Wednesday, January 28, 2004 5:42 PM

APPENDIX

B

AgGPS 252 Receiver User Guide 59

Third-Party Interface
Requirements

B

B.1

Third-Party Software

Table B.1 lists the interface requirements for connecting an AgGPS

receiver to third-party software.

Use cable P/N 50166, or 30945 plus 50581, when connecting to the
third-party software products listed.

Table B.1 Third-party software interface requirements

Software Company Protocol NMEA

messages

Baud Other Pos rate

AgView GIS Solutions NMEA VTG, GLL 4800 8-N-1 1Hz
FarmGPS Red Hen NMEA GGA, GSA, VTG 4800 8-N-1 1Hz
Field Rover SST Dev

Group

NMEA GGA, GSA, GSV,

VTG

4800 8-N-1 1Hz

FieldLink DOS Agris NMEA GGA, GSA, VTG 4800 or

9600

8-N-1 1Hz

FieldLink
Windows

Agris NMEA GGA, GSA, VTG 4800 or

9600

8-N-1 1Hz

Ag252_100A_UserGde_ENG.book Page 59 Wednesday, January 28, 2004 5:42 PM

B Third-Party Interface Requirements

60 AgGPS 252 Receiver User Guide

Field Worker
Pro

Field Worker NMEA GGA, GLL, RMC,

VTG

4800 or
9600

8-N-1 1Hz

HGIS Starpal NMEA GGA, RMC 4800 or

9600

8-N-1 1Hz

Instant Survey Agrilogic

(Case-IH)

NMEA GGA, GSA, RMC 4800 8-N-1 1Hz

Pocket Survey Agrilogic

(Case-IH)

NMEA GGA, GSA, RMC 4800 8-N-1 1Hz

Sitemate Farmworks NMEA GGA, VTG 4800 8-N-1 1Hz

Table B.1 Third-party software interface requirements (continued)

Software Company Protocol NMEA

messages

Baud Other Pos rate

Ag252_100A_UserGde_ENG.book Page 60 Wednesday, January 28, 2004 5:42 PM

AgGPS 252 Receiver User Guide 61

Third-Party Interface Requirements B

B.2 Third-Party Hardware

Table B.2 lists the interface requirements for connecting an AgGPS

receiver to third-party hardware.

Table B.2 Third-party hardware interface requirements

Hardware Company Protocol NMEA

messages

Baud Other Pos

rate

Cable P/N

AMS Raven NMEA GGA, VTG 9600 8-N-1 1Hz

50166, or
30945
plus
50581

Ag
Navigator

Springhill RTCM 9600 8-N-1 10Hz

Aim
Navigator

Case Tyler NMEA GGA 19200 8-N-1 5Hz

Contour Position Inc. NMEA GGA 19200 8-N-1 5Hz
Marker RDS or

Position Inc.

NMEA GGA 19200 8-N-1 5Hz

Falcon Ag Chem NMEA GGA, VTG 4800 8-N-1 1Hz
Falcon w/

Falcon Track
LBAR

Ag Chem NMEA GGA, VTG 19200 8-N-1 10Hz

50166, or
30945
plus
50581

Swath
Smart or
RGL 500
(LB-5 for
Raven)

Raven,
Starlink
manufactured

NMEA GGA, VTG

or RMC

19200 8-N-1 10hz

LB-3, LB-4,
and LB-5

Starlink NMEA GGA, VTG

or RMC

19200 8-N-1 10hz

YM2000
Yield
Monitor

1

Ag Leader NMEA GGA, VTG 4800 8-N-1 1 Hz 39903

plus
50581

PF3000
Yield
Monitor

1

Ag Leader NMEA GGA, VTG 4800 8-N-1 1 Hz 39903

plus
50581

Ag252_100A_UserGde_ENG.book Page 61 Wednesday, January 28, 2004 5:42 PM

B Third-Party Interface Requirements

62 AgGPS 252 Receiver User Guide

PF3000Pro
Monitor
without
internal
GPS

2

Ag Leader NMEA GGA, VTG 4800 8-N-1 1 Hz 39903

plus
50581

AFS Yield
Monitor

Case-IH
(Ag Leader
YM2000)

NMEA GGA, VTG 4800 8-N-1 1 Hz 32609

plus
50581

AFS Yield
Monitor

Case-IH
YMIU (yield
monitor
interface unit)
manufactured
by Ag Leader
for Case-IH

NMEA GGA, VTG 4800 8-N-1 1 Hz 32609

plus
50581

GreenStar
Yield
Monitor

3

John Deere NMEA GGA,

GSA, RMC

4800 8-N-1 1 Hz 34189

plus
50581

New
Holland
Yield
Monitor

New Holland
(Ag Leader
PF3000)

NMEA GGA, VTG 4800 8-N-1 1 Hz 39903

plus
50581

VCD (Vision
Display
Controller)

Rockwell NMEA GGA, GLL,

VTG, ZDA

4800 8-N-1 1 Hz 50166, or

30945
plus
50581

Table B.2 Third-party hardware interface requirements (continued)

Hardware Company Protocol NMEA

messages

Baud Other Pos

rate

Cable P/N

Ag252_100A_UserGde_ENG.book Page 62 Wednesday, January 28, 2004 5:42 PM

AgGPS 252 Receiver User Guide 63

Third-Party Interface Requirements B

Swath XL Midtech NMEA GGA 19200 8-N-1 5 Hz 50166, or

30945
plus
50581

Caterpillar
Cebis Yield
Monitor

Claus NMEA GGA 4800

or
9600

8-N-1 1 Hz 50166, or

30945
plus
50581

AGCO
FieIdStar
Yield
Monitor

4

AGCO NMEA GGA,

VTG, GSV,
GSA

4800 8-N-1 1 Hz 39903

plus
50581

1

P/N 39903 replaced old Ag Leader cable P/N 30660.

2

Connect to Aux port.

3

Older GreenStars with version 5.3P mapping processor software require 9600 baud. Older GreenStars with

version 5.3R mapping processor software require 4800 baud.

4

AGCO unit requires a null modem RS-232 connection. Ag Leader cable P/N 39903 is wired correctly for

connection.

Table B.2 Third-party hardware interface requirements (continued)

Hardware Company Protocol NMEA

messages

Baud Other Pos

rate

Cable P/N

Ag252_100A_UserGde_ENG.book Page 63 Wednesday, January 28, 2004 5:42 PM

B Third-Party Interface Requirements

64 AgGPS 252 Receiver User Guide

Ag252_100A_UserGde_ENG.book Page 64 Wednesday, January 28, 2004 5:42 PM

AgGPS 252 Receiver User Guide 65

Index

1 PPS output 7

A

accuracy 4, 10
adapter cable 21
AFS Yield Monitor 62
Ag Navigator 61
AGCO FieldStar Yield Monitor 63
AgGPS 170 Field Computer 4, 35
AgRemote utility 28

activating OmniSTAR 31
configuring ports 33
downloading 28
for RTK mode 33
Home screen 29
no GPS position 43
troubleshooting 46
viewing and configuring settings 1
WAAS/EGNOS 32

web document 29
AgView 59
Aim Navigator 61
altitude 13
AMS 61
antenna

electrical interference 20

location of 19

mounting 20
ASCII input 6
Autopilot, connecting to 21, 25

B

battery, real-time clock 46

C

cables 6

avoiding bent 21
connection diagram 22
external device 21
pinout 24
routing 23
SiteNet radio 21
third-party hardware 61
third-party software 59

troubleshooting 45
CAN bus protocol 5, 7
casing, specification 55
Caterpillar Cebis Yield Monitor 63
centimeter-level accuracy 10
changing

battery 46

correction source 31

port setting and protocol 34
characteristics 55
Class A digital device, FCC notice iii
CMR

corrections for RTK 10, 35, 56

input 6

LED sequences 9
COM port 46

Ag252_100A_UserGde_ENG.book Page 65 Wednesday, January 28, 2004 5:42 PM

Index

66 AgGPS 252 Receiver User Guide

compliance, specification 56
components 18
configuring

RTK 33
WAAS/EGNOS DGPS 32

connecting to external devices 21
connector ports see ports
connectors 6

specification 56

Contour 61
Controller Area Network bus protocol see

CAN bus protocol
convergence 12
coordinate systems 15
correction source, changing 31
corrections, free or subscription 11

D

data/power cable 6
Declaration of Conformity iv
default settings, receiver 58
Differential GPS (DGPS) positioning

method 11

configuring 33
if accuracy poor 41

E

EGNOS

accuracy 10
DGPS, configuring 32

website 11
electrical interference, sources of 20
elevation 14
Elevation mask 41
enhancements 18
environmental conditions for receiver 20
ephemeris (satellite history) file 13

European Geostationary Navigation Overlay

System see EGNOS

European Space Agency website 11
expiry date, OmniSTAR VBS 52
external devices, connecting to 21

F

factory defaults 46
Falcon 61
Falcon with Falcon Track LBAR 61
FarmGPS 59
FCC notice, Class A digital device iii
features 4
Federal Aviation Administration website 11
Field Rover 59
Field Worker Pro 60
FieldLink DOS 59
FieldLink Windows 59
FlashLoader 200 utility, troubleshooting 47
FM 2-way radios 44
free corrections 11

G

GPS error, sources of 13
GPS Mode 41
GPS positioning methods 10
GPS positions

output format 8
output of 15

GPS reception

troubleshooting 50
troubleshooting (third-party

device) 51

GreenStar Yield Monitor 62

Ag252_100A_UserGde_ENG.book Page 66 Wednesday, January 28, 2004 5:42 PM

Index

AgGPS 252 Receiver User Guide 67

H

hardware

third-party 61

troubleshooting 49
HGIS 60
Home screen

AgRemote utility 29

satellites tracked 42
horizontal accuracy 4
humidity, specifications 55

I

information, more 2, 7, 29
input, TSIP, RTCM, and ASCII 6
inputs 6
Instant Survey 60
ISO 11783 5

J

J1939 CAN bus 5, 7

L

latitude 13
LB-3, LB-4, LB-5 61
LED indicator 8
location of antenna 19
location of receiver 19
longitude 13

M

Marker 61
mounting plate assembly 18, 19
mounting, specification 56

multipath

and accuracy 14
EVEREST technology 4
GPS channels 57
reducing 41

N

National Geodetic Survey website 15
National Marine Electronics Association see

NMEA
New Holland Yield Monitor 62
NMEA

output 6, 37
protocol 5
screens 37
web document 7
website 7

O

OmniSTAR

expiry date 52
HP Differential GPS positioning

method 9, 10, 12
satellite beam 42
troubleshooting 52
VBS Differential GPS positioning

method 10, 12
website 12

optional extras 18
output 6

1 PPS 7
RTCM, TSIP, NMEA, 1 PPS 6

overview 3

P

P-clip 21

Ag252_100A_UserGde_ENG.book Page 67 Wednesday, January 28, 2004 5:42 PM

Index

68 AgGPS 252 Receiver User Guide

PDOP 13
PDOP Mask 41
performance of GPS channels 56
PF3000 Yield Monitor 61
physical characteristics 55
pinout for cables 24
Pocket Survey 60
Port A Config screen 36
Port A Input/Output screen 36
port setting and protocol, changing 34
ports 5

CAN, ISO 11783 support 7
configuring 33
covering when not in use 23
output 4
serial, CAN bus support 7
setting output rate 37

specification 56
position output formats 8, 15
positioning method

Differential GPS (DGPS) 11

OmniSTAR HP 9

RTK GPS positioning 9

Satellite Differential GPS 8
power

specification 55

troubleshooting 49
protocol

CAN bus 7

NMEA 5

RTC M 5

RtkLnk 6

third-party software 59

TSIP 5

R

Radio Technical Commission for Maritime

Services see RTCM

Real-Time Kinematic (RTK) GPS

positioning method 10

accuracy 10
base station coordinates 14
configuring for 33
datum and ellipsoid 15
GPS performance 56
LEDs 9
number of satellites 13
option 18
port settings 35
radio connection 21
RtkLnk protocol 6
troubleshooting 53

vertical and horizontal accuracy 4
receiving DGPS 11
reception

troubleshooting 50

troubleshooting (third-party

device) 51
release notes 2
RF3000Pro Monitor without internal GPS

third party hardware 62
RGL 500 (LB-5 for Raven) 61
routing cables 23
RS-232 5, 56, 63
RTCM

input 6

output 6

protocol 5

website 7
RTK see Real-Time Kinematic (RTK) GPS

positioning method

RtkLnk protocol 6

port input setting 35

S

SAE International website 7

Ag252_100A_UserGde_ENG.book Page 68 Wednesday, January 28, 2004 5:42 PM

Index

AgGPS 252 Receiver User Guide 69

Satellite Differential GPS positioning

method 8

accuracy 10
satellite history (ephemeris) file 13
satellites, number used 13
settings 34
Signal Strength Mask 41
signal-to-noise ratio (SNR) 14, 45
Sitemate 60
SiteNet 900 radio settings 36
size, specification 55
software

AgRemote 28

third-party 59
specifications 55
standard features 4
standard power/data connections 22
subscription-based corrections 12
Swath Smart 61
Swath XL 63

T

technical assistance 2
temperature, operating and storage

specification 55

third-party

hardware 61

software 59
time 13
time to output positions 46
Trimble Standard Interface Protocol see

TSIP
Trimble website 1
troubleshooting

AgRemote 43
AgRemote communication 46
battery 46
cables 45
FlashLoader 200 47

GPS reception 50
GPS reception (third-party device) 51
hardware and power 49
initialization 43
intermittent DGPS 41
OmniSTAR 52
poor accuracy 41
Real-Time Kinematic (RTK) GPS

positioning method 53
receiver location 45
restoring defaults 46
RTK 44

TSIP

AgRemote setting change 35
input 6
output 6, 37

U

utility

AgRemote 28
FlashLoader 200 47

V

vertical accuracy 4
Vision Display Controller 62

W

WA A S

accuracy 10
DGPS, configuring 32
website 11

WAAS/EGNOS corrections, accuracy 10
warnings 2

Class A product iii
fuse to be provided 19

Ag252_100A_UserGde_ENG.book Page 69 Wednesday, January 28, 2004 5:42 PM

Index

70 AgGPS 252 Receiver User Guide

websites

European Space Agency 11
Federal Aviation Administration 11
for EGNOS 11
for WAAS 11
National Geodetic Survey 15
NMEA 7
OmniSTAR 12
RTC M 7
SAE International 7
Trimble 1
WAAS 11

weight, specification 55
Wide Area Augmentation System see WAA S

Y

YM2000 Yield Monitor 61

Ag252_100A_UserGde_ENG.book Page 70 Wednesday, January 28, 2004 5:42 PM