Trimble Outdoors Satellite TV System AgGPS 252 User Manual

User Guide  
AgGPS®252 Receiver  
Version 1.00  
Revision B  
Part Number 55510-00-ENG  
August 2005  
 
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.  
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).  
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  
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).  
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.  
Warning – This is a Class A product. In a  
domestic environment this product may cause  
C
radio interference in which case you may be  
required to take adequate measures.  
Notice to Our European Union Customers  
For product recycling instructions and more information,  
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:  
Recycling in Europe:  
To recycle Trimble WEEE (Waste  
Electrical and Electronic Equipment,  
products that run on electrical power.),  
Call +31 497 53 24 30, and ask for the  
"WEEE Associate".  
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.  
Or, mail a request for recycling  
instructions to:  
Trimble Europe BV  
c/o Menlo Worldwide Logistics  
Meerheide 45  
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.  
5521 DZ Eersel, NL  
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.  
EMC Emissions  
EMC Immunity  
Safety  
BSEN 55022:1998 (W/A1:00) Class A  
EN 55024:1998  
EN 60950:2000  
03  
Mark First Applied  
The technical file is maintained at Trimble Navigation Limited, 749 North Mary Avenue, PO Box 3642, Sunnyvale, CA  
94088-3642, USA.  
 
     
 
1
Introduction . . . . . . . . . . . . . . . . . . . . . . . 1  
2
3
Optional extra . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18  
Mounting the Receiver. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19  
Choosing a location . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19  
Environmental conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20  
Electrical interference . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20  
Connecting to an External Device . . . . . . . . . . . . . . . . . . . . . . . . . . . 21  
AgGPS 252 Receiver User Guide  
v
 
Contents  
Port B . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25  
4
Configuring the AgGPS 252 Receiver to Operate in RTK Mode . . . . . . . . . 31  
Configuring input/output communication. . . . . . . . . . . . . . . . . . 32  
5
Troubleshooting Flowcharts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45  
A
GPS Channels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54  
Receiver Default Settings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56  
B
Third-Party Interface Requirements . . . . . . . . . 57  
Third-Party Software . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57  
Third-Party Hardware . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58  
Index . . . . . . . . . . . . . . . . . . . . . . . . . . 61  
vi AgGPS 252 Receiver User Guide  
 
C H A P T E R  
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.  
AgGPS 252 Receiver User Guide  
1
 
     
1
Introduction  
1.1  
Warnings  
Always follow the instructions that accompany a warning.  
WARNING – Indicates a potential hazard or unsafe practice that could  
result in injury or property damage.  
C
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  
2
AgGPS 252 Receiver User Guide  
 
             
C H A P T E R  
2
2
Q Standard Features of the AgGPS 252 Receiver  
Q Receiver Connections  
Q Receiver Input/Output  
Q LED Indicator  
Q GPS Positioning Methods  
Q Sources of Error in GPS Positioning  
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.  
AgGPS 252 Receiver User Guide  
3
 
     
2
Overview  
2.1  
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)  
+ 2 ppm, 2 sigma  
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  
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  
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  
4
AgGPS 252 Receiver User Guide  
 
               
Overview  
2
NMEA-0183 output: GGA, GLL, GRS, GST, GSA, GSV, MSS,  
RMC, VTG, ZDA, XTE (the default NMEA messages are  
GGA, GSA, VTG, and RMC)  
PTNLDG, PTNLEV, PTNLGGK, PTNLID, and  
PTNLSM are Trimble proprietary NMEA output messages.  
RTCM SC-104 output  
Trimble Standard Interface Protocol (TSIP) input and  
output  
2.2  
Receiver Connections  
Figure 2.1 shows the connector ports and the LED indicator on the  
AgGPS 252 receiver.  
Port A  
Port B  
LED indicator  
Figure 2.1  
AgGPS 252 receiver connector ports  
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  
AgGPS 252 Receiver User Guide  
5
 
             
2
Overview  
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.  
2.3  
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.  
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:  
6
AgGPS 252 Receiver User Guide  
 
                       
Overview  
2
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.  
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.  
AgGPS 252 Receiver User Guide  
7
 
                     
2
Overview  
2.4  
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.  
Table 2.1  
LED sequences with Satellite Differential GPS or Autonomous  
positioning  
LED color LED flash  
Status  
Off  
Off  
No power  
Green  
Green  
Solid  
Slow  
Normal operation: computing DGPS positions  
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  
Yellow  
Slow  
Fast  
No DGPS corrections: computing autonomous GPS positions  
Not enough GPS signals: not tracking enough satellites to compute  
position  
Note – WAAS/EGNOS and OmniSTAR VBS use the Satellite Differential  
GPS positioning method.  
Table 2.2  
LED sequences with RTK positioning  
LED color LED flash Status  
Off  
Off  
No power  
Green  
Green  
Solid  
Slow  
Normal operation: computing fixed RTK positions  
Receiving CMR corrections but not initialized: computing float RTK  
positions  
Green  
Fast  
No CMR corrections: computing RTK position using old corrections  
8
AgGPS 252 Receiver User Guide  
 
         
Overview  
2
Table 2.2  
LED sequences with RTK positioning (continued)  
LED color LED flash Status  
Yellow  
Solid  
Receiving CMR corrections but unable to calculate RTK position:  
computing DGPS (if WAAS/EGNOS is unavailable) or autonomous  
position  
Yellow  
Yellow  
Slow  
Fast  
No CMR corrections: computing DGPS or autonomous position  
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  
Green  
Solid  
Slow  
Normal operation: computing converged OmniSTAR HP positions  
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  
Yellow  
Slow  
Fast  
No OmniSTAR HP corrections: computing DGPS or autonomous  
position  
Not tracking OmniSTAR HP corrections: no positions  
2.5  
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).  
AgGPS 252 Receiver User Guide  
9
 
     
2
Overview  
Table 2.4 summarizes the GPS positioning methods. Imperial units in  
this table are rounded to two decimal places. The values shown are  
2 sigma.  
Table 2.4  
Absolute accuracy of GPS positioning methods  
GPS positioning  
method  
Corrections used  
Approximate absolute accuracy  
Real-Time Kinematic  
(RTK) GPS  
Trimble CMR corrections 2.5 cm (0.98 in) + 2 ppm horizontal  
broadcast by a local  
base station  
accuracy,  
3.7 cm (1.46 in) + 2 ppm vertical accuracy  
Satellite Differential GPS OmniSTAR VBS  
Satellite Differential GPS WAAS/EGNOS  
78 cm (30.71 in)  
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.  
For more information about each positioning method, see below.  
25.1  
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.  
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.  
10 AgGPS 252 Receiver User Guide  
 
                   
Overview  
2
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  
25.2  
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  
For more information about EGNOS, go to the European Space Agency  
website at  
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  
AgGPS 252 Receiver User Guide 11  
 
                     
2
Overview  
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 29.  
25.3  
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.  
12 AgGPS 252 Receiver User Guide  
 
     
Overview  
2
2.6  
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  
Condition  
Factors that influence the accuracy of GPS positions  
Optimum Description  
value  
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 RTK 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.  
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:  
GPS6  
WAAS3+  
OmniSTAR HP/VBS6+  
AgGPS 252 Receiver User Guide 13  
 
                       
2
Overview  
Table 2.5  
Condition  
Factors that influence the accuracy of GPS positions (continued)  
Optimum Description  
value  
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.  
RTCM-  
These corrections are broadcast from a Trimble AgGPS 214,  
compatible  
corrections  
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. For more information about how to  
use several base stations to cover your site, contact your local  
Trimble Reseller.  
26.1  
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.  
14 AgGPS 252 Receiver User Guide  
 
         
Overview  
2
The AgGPS 252 receiver outputs position coordinates in several datums  
and ellipsoids depending on the GPS positioning method being used.  
See Table 2.6.  
Table 2.6  
DGPS coordinate systems  
GPS positioning method  
None – Autonomous mode  
OmniSTAR VBS North American Beams  
OmniSTAR VBS Rest of World Beams  
OmniSTAR HP  
Datum  
WGS-84  
NAD-83  
Ellipsoid  
WGS-84  
GRS-80  
1
2
3
ITRF  
GRS-80  
ITRF 2000  
WGS-84  
WGS-84  
ITRF 2000  
WGS-84  
WGS-84  
WAAS Beams  
RTK  
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.  
For more information, go to the National Geodetic Survey website at  
AgGPS 252 Receiver User Guide 15  
 
     
2
Overview  
16 AgGPS 252 Receiver User Guide  
 
C H A P T E R  
3
3
In this chapter:  
Q System Components  
Q Mounting the Receiver  
Q Connecting to an External Device  
Q Connectors and Pinouts  
This chapter describes how to check the equipment that you have  
received, set up the receiver, and connect the receiver to another  
device.  
AgGPS 252 Receiver User Guide 17  
 
 
3
Installing the Receiver  
3.1  
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.  
Table 3.1  
AgGPS 252 receiver (P/N 55500-XX)  
Quantity  
Description  
1
1
1
1
1
AgGPS 252 DGPS receiver (P/N 55500-01)  
System level cable (P/N 50165 or 50166)  
Mounting plate assembly (P/N 51312-00)  
Port B plug (P/N 51062)  
AgGPS 252 Receiver User Guide  
(this manual, P/N 55510-00-ENG)  
1
1
Warranty Activation Card (P/N 25110-00)  
OmniSTAR Activation Card (P/N 33965)  
31.1  
Optional extra  
You may also have ordered the following item:  
Table 3.2  
Receiver option  
Quantity  
Description  
1
RTK capability (P/N 51264)  
18 AgGPS 252 Receiver User Guide  
 
           
Installing the Receiver  
3
3.2  
Mounting the Receiver  
WARNING – For continued protection against the risk of fire, the power  
source (lead) to the model AgGPS 252 receiver should be provided with a  
10 A (maximum) fuse.  
C
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.  
32.1  
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  
near transmitting antennas, radar arrays, or satellite  
communication equipment  
AgGPS 252 Receiver User Guide 19  
 
           
3
Installing the Receiver  
near areas that experience high vibration, excessive heat,  
electrical interference, and strong magnetic fields  
Note – A metal combine grain tank extension can block  
satellites.  
32.2  
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  
32.3  
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  
high-voltage power lines  
20 AgGPS 252 Receiver User Guide  
 
       
Installing the Receiver  
3
CB radio antennas  
cellular phone antennas  
machine accessory lights  
3.3  
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 connect the AgGPS 252  
use the cable ...  
receiver to ...  
an Autopilot system  
P/N 50165  
(this cable has no DB9 connector)  
a Field computer  
a Yield monitor  
P/N 50166  
P/N 50166  
P/N 49801  
a Trimble SiteNet™ radio, for RTK  
positioning  
To convert the AgGPS 252 receiver to a Trimble 12-pin conxall cable,  
use the adapter cable (P/N 50581).  
Plug the ...  
into ...  
Deutsch 12-pin connector  
straight DB9-pin connector  
power connectors  
Port A on the back of the receiver  
the external device  
a power supply  
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.  
AgGPS 252 Receiver User Guide 21  
 
               
3
Installing the Receiver  
Figure 3.1 shows how to connect the receiver to an external device  
using the system level cable (P/N 50166).  
LED indicator  
AgGPS 252 receiver  
Port A  
Port B  
Deutsch 12-pin  
System level  
cable (P/N 50166)  
DB9  
To external  
device  
Ground –ve  
Power +ve  
Figure 3.1  
Standard power/data cable connections  
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  
22 AgGPS 252 Receiver User Guide  
 
     
Installing the Receiver  
3
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.  
AgGPS 252 Receiver User Guide 23  
 
 
3
Installing the Receiver  
3.4  
Connectors and Pinouts  
Use the following pinout information if you need to wire a cable for use  
with the AgGPS 252 receiver.  
1
2
3
4
9
5
8
6
7
12  
11  
10  
Figure 3.2  
AgGPS 252 receiver port pinout  
34.1  
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.  
Table 3.3  
Port A pinout  
Pin  
1
Name/Function  
CAN A High I/O  
Comments  
2
Port 1 RS232 Tx OUT  
When held to ground during power up,  
puts unit into Monitor mode  
3
4
Port 1 RS232 Rx IN  
PPS OUT  
24 AgGPS 252 Receiver User Guide  
 
       
Installing the Receiver  
3
Table 3.3  
Port A pinout (continued)  
Pin  
Name/Function Comments  
5
Signal GND  
Used for RS232 and other signals. Should  
not be connected to  
V– (battery negative)  
6
Port 1 RTS OUT  
Event OUT / Alarm OUT  
Port 1 CTS IN  
Event IN  
7
8
9
10  
11  
12  
V+ IN  
V- IN  
CAN A Low I/O  
34.2  
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.  
Table 3.4  
Port B pinout  
Pin  
1
Name/Function  
CAN B High I/O  
Port 2 RS232 Tx OUT  
Port 2 RS232 Rx IN  
PPS OUT  
Comments  
2
3
4
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
8
Event OUT / Alarm OUT  
Port 2 CTS IN or Port 3  
RS232 Rx IN  
AgGPS 252 Receiver User Guide 25  
 
 
3
Installing the Receiver  
Table 3.4  
Port B pinout (continued)  
Pin  
9
Name/Function Comments  
Event IN  
10  
11  
12  
V+ IN / OUT  
V– IN / OUT  
CAN B Low I/O  
Maximum output current = 1.25 A  
Maximum output current = 1.25 A  
26 AgGPS 252 Receiver User Guide  
 
C H A P T E R  
4
In this chapter:  
Q AgRemote Home Screen  
Q Configuring Differential GPS  
Q Configuring the AgGPS 252 Receiver to Operate in RTK Mode  
Q Configuring the Communication Ports  
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 29.  
AgGPS 252 Receiver User Guide 27  
 
       
4
Configuring the Receiver  
4.1  
AgRemote Home Screen  
Figure 4.1 shows the AgRemote Home screen when WAAS corrections  
are being received.  
Number of GPS satellites being tracked  
Position type  
Current PDOP value  
GPS indicators  
D/3D í07 DOP03  
WAAS 122 ÷ø04  
Correction  
indicators  
Correction type  
Signal-to-Noise ratio  
of DGPS satellite  
DGPS satellite name or ID  
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.  
4.2  
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.  
28 AgGPS 252 Receiver User Guide  
 
             
Configuring the Receiver  
4
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.  
42.1  
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  
AgGPS 252 Receiver User Guide 29  
 
       
4
Configuring the Receiver  
serial number  
satellite beam name  
OmniSTAR will activate the receiver. Activation can take  
5–30 minutes.  
40.1  
WAAS/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.  
30 AgGPS 252 Receiver User Guide  
 
     
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.  
AgGPS 252 Receiver User Guide 31  
 
             
4
Configuring 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.  
Repeat the above steps but in Step 2 select Configuration / Port B  
Config.  
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  
32 AgGPS 252 Receiver User Guide  
 
     
Configuring the Receiver  
4
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.  
Table 4.1  
Port input settings  
Setting  
None  
Description  
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.  
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  
TSIP  
The receiver can accept RTCM data from an external DGPS device,  
such as an external radio.  
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.  
The default port settings are:  
Port A  
Port B  
Baud rate  
In  
TSIP 38,400  
TSIP 38,400  
Out  
TSIP 38,400  
TSIP 38,400  
Data bits  
Parity  
8
8
None  
1
None  
1
Stop bits  
AgGPS 252 Receiver User Guide 33  
 
         
4
Configuring the Receiver  
Note – The AgRemote utility, when connected to an AgGPS 252 receiver  
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.  
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:  
Setting  
Baud rate  
Data bits  
Parity  
Description  
38,400  
8
None  
1
Stop bits  
Changing the input or output port settings  
1. From the Port A Config screen, press 2 until the Port-A  
Input/Output screen appears:  
åæ I RTCM 9600  
8N1 0 NMEA 4800  
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.  
34 AgGPS 252 Receiver User Guide  
 
       
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.  
AgGPS 252 Receiver User Guide 35  
 
     
4
Configuring the Receiver  
36 AgGPS 252 Receiver User Guide  
 
C H A P T E R  
5
5
In this chapter:  
Q
Q Problems and Solutions  
Q Troubleshooting Flowcharts  
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  
5.1  
Problems and Solutions  
If you encounter a problem, try the following solutions.  
AgGPS 252 Receiver User Guide 37  
 
     
5
Troubleshooting  
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.  
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).  
The receiver always calculates the  
most accurate position it can, given  
the current GPS satellite differential  
operating conditions.  
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.  
38 AgGPS 252 Receiver User Guide  
 
                 
Troubleshooting  
5
Problem  
Possible solution  
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.  
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  
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  
Omni VBS Info  
2. Press 4 until Stop Date  
If the message Access Unknown appears, contact  
OmniSTAR to reactivate your subscription. For more  
information, see OmniSTAR, page 29.  
HP and RTK also give an indication  
of positional accuracy on the Home  
screen (AgRemote).  
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.  
AgGPS 252 Receiver User Guide 39  
 
   
5
Troubleshooting  
Problem  
Possible solution  
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.  
Connect AgRemote. Then reset the port  
communication settings to NMEA output. For more  
information, see Configuring the Communication  
Ports, page 31.  
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.  
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 receiver 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  
40 AgGPS 252 Receiver User Guide  
 
     
Troubleshooting  
5
Problem  
Possible solution  
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.  
AgGPS 252 Receiver User Guide 41  
 
 
5
Troubleshooting  
Interference  
Problem  
Possible solution  
Strong magnetic fields  
Strong magnetic fields have no  
effect on GPS or satellite DGPS  
signals.  
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 signal-  
to-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.  
However, some computers and other  
electric equipment radiate  
electromagnetic energy that can  
interfere with a GPS receiver.  
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  
Use resistor spark plug wires on the vehicle ignition  
system.  
reception of a differential signal.  
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.  
42 AgGPS 252 Receiver User Guide  
 
   
Troubleshooting  
5
GPS receiver  
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.  
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 the battery fails,  
the internal clock cannot keep  
Please contact your local Trimble Reseller to get  
the batteries replaced. You cannot replace the  
battery yourself.  
accurate time and the receiver may  
take longer to output GPS positions.  
Factory defaults  
You need to restore the receiver  
factory defaults.  
To restore receiver factory default settings:  
Connect the receiver to a computer. Turn on the  
receiver.  
2. Run the AgRemote utility.  
3. Navigate to the Clear BB RAM  
4. Press 2 until Yes appears.  
5. Press 4.  
The factory default settings are restored. The DGPS  
service subscription is not lost.  
AgGPS 252 Receiver User Guide 43  
 
             
5
Troubleshooting  
AgRemote utility  
Problem  
Possible solution  
AgRemote cannot communicate  
with the receiver. All you see is a  
blank screen.  
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  
Select File / Connect  
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:  
From the FlashLoader 200 menu, select  
Settings  
Select the check box for a serial link.  
3. At Port, select Auto. Click OK.  
4. Select the Upload firmware to receiver  
Proceed  
6. From the Auto Port Select dialog,  
receiver on port... OK  
Use  
Once you have checked this, turn off the receiver  
then turn it on again. Try again to connect  
FlashLoader 200.  
44 AgGPS 252 Receiver User Guide  
 
       
Troubleshooting  
5
5.1  
Troubleshooting 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.  
AgGPS 252 Receiver User Guide 45  
 
 
5
Troubleshooting  
46 AgGPS 252 Receiver User Guide  
 
Troubleshooting Flowcharts  
Figure 6.1  
Troubleshooting system hardware and power  
AgGPS 252 Receiver User Guide 47  
 
 
Troubleshooting Flowcharts  
Figure 6.2  
Using AgRemote to troubleshoot GPS reception  
(no third-party device attached)  
48 AgGPS 252 Receiver User Guide  
 
 
Troubleshooting Flowcharts  
Figure 6.3  
Using AgRemote to troubleshoot GPS reception (third-party device attached)  
AgGPS 252 Receiver User Guide 49  
 
 
Troubleshooting Flowcharts  
Figure 6.4  
Using AgRemote to troubleshoot OmniSTAR positioning  
50 AgGPS 252 Receiver User Guide  
 
   
Troubleshooting Flowcharts  
Figure 6.5  
Using AgRemote to troubleshoot RTK  
AgGPS 252 Receiver User Guide 51  
 
 
Troubleshooting Flowcharts  
52 AgGPS 252 Receiver User Guide  
 
A P P E N D I X  
A
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  
Power  
2.1 kg  
Nominal 350 mA at 12 V DC  
Operating temperature  
Storage temperature  
Humidity  
–30 °C (–22 °F) through +70 °C (+158 °F)  
–40 °C (–40 °F) through +85 °C (+185 °F)  
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.  
Connectors  
12-pin Deutsch connectors  
AgGPS 252 Receiver User Guide 53  
 
                       
A
Specifications  
Table A.1  
AgGPS 252 receiver (continued)  
Item  
Description  
Ports  
Two connection ports, both of which support RS-232 and CAN  
Mounting  
Compliance  
Three holes for 10 mm (0.39 in) bolts  
FCC Part 15 Class A, C-Tick, E-mark,  
CE-mark  
A.2  
GPS Channels  
Table A.2 lists the performance characteristics of GPS channels.  
Table A.2  
GPS channels performance  
Description  
Item  
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)  
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)  
54 AgGPS 252 Receiver User Guide  
 
                 
Specifications  
A
Table A.2  
Item  
GPS channels performance (continued)  
Description  
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  
1
NMEA messages  
GGA 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 1 Hz  
(1 position per second) update rate.  
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.  
Table A.3  
L-Band satellite differential correction receiver with  
OmniSTAR support  
Item  
Description  
-5  
Bit error rate  
10 for Eb/N of >5.5 dB  
Acquisition and reacquisition time  
Frequency band  
<5 seconds, typical  
1525–1559 MHz  
0.5 kHz  
Channel spacing  
AgGPS 252 Receiver User Guide 55  
 
     
A
Specifications  
A.4  
Receiver Default Settings  
Table A.4 lists the receiver default settings.  
Table A.4  
Receiver default settings  
Item  
Description  
DGPS source  
Dynamics  
WAAS/EGNOS  
Land  
Minimum elevation  
AMU mask  
8°  
3
PDOP mask  
13  
PDOP 2D/3D switch  
DGPS mode  
11  
Auto On/Off  
250 seconds  
1 Hz  
DGPS correction age limit  
Pos fix rate  
56 AgGPS 252 Receiver User Guide  
 
     
A P P E N D I X  
B
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  
AgView  
Company  
GIS Solutions  
Red Hen  
Protocol NMEA messages Baud  
Other Pos rate  
NMEA  
NMEA  
VTG, GLL  
4800  
4800  
4800  
8-N-1  
8-N-1  
8-N-1  
1Hz  
1Hz  
1Hz  
FarmGPS  
Field Rover  
GGA, GSA, VTG  
SST Dev Group NMEA  
GGA, GSA, GSV,  
VTG  
FieldLink DOS  
Agris  
NMEA  
NMEA  
NMEA  
GGA, GSA, VTG  
4800 or 8-N-1  
9600  
1Hz  
1Hz  
1Hz  
FieldLink  
Windows  
Agris  
GGA, GSA, VTG  
4800 or 8-N-1  
9600  
Field Worker  
Pro  
Field Worker  
GGA, GLL, RMC,  
VTG  
4800 or 8-N-1  
9600  
AgGPS 252 Receiver User Guide 57  
 
                       
B
Third-Party Interface Requirements  
Table B.1  
Third-party software interface requirements (continued)  
Software  
Company  
Protocol NMEA messages Baud  
Other Pos rate  
HGIS  
Starpal  
NMEA  
NMEA  
NMEA  
GGA, RMC  
4800 or 8-N-1  
9600  
1Hz  
1Hz  
1Hz  
1Hz  
Instant Survey  
Pocket Survey  
Sitemate  
Agrilogic  
(Case-IH)  
GGA, GSA, RMC  
GGA, GSA, RMC  
GGA, VTG  
4800  
8-N-1  
8-N-1  
8-N-1  
Agrilogic  
(Case-IH)  
4800  
4800  
Farmworks  
B.2  
Third-Party Hardware  
Table B.2 lists the interface requirements for connecting an AgGPS  
receiver to third-party hardware.  
Table B.2  
Hardware  
Third-party hardware interface requirements  
Company  
Protocol NMEA  
messages  
Baud  
Other Pos  
rate  
Cable P/N  
AMS  
Raven  
NMEA  
RTCM  
NMEA  
GGA, VTG  
9600  
9600  
8-N-1 1Hz  
8-N-1 10Hz  
Ag Navigator Springhill  
Aim  
Case Tyler  
GGA  
19200 8-N-1 5Hz  
50166, or  
30945 plus  
50581  
Navigator  
Contour  
Marker  
Position Inc.  
NMEA  
NMEA  
GGA  
GGA  
19200 8-N-1 5Hz  
19200 8-N-1 5Hz  
RDS or  
Position Inc.  
Falcon  
Ag Chem  
NMEA  
GGA, VTG  
4800  
8-N-1 1Hz  
58 AgGPS 252 Receiver User Guide  
 
                           
Third-Party Interface Requirements  
Third-party hardware interface requirements (continued)  
B
Table B.2  
Hardware  
Company  
Protocol NMEA  
messages  
Baud  
Other Pos  
rate  
Cable P/N  
Falcon w/  
Falcon Track  
LBAR  
Ag Chem  
NMEA  
GGA, VTG  
19200 8-N-1 10Hz  
Swath Smart Raven, Starlink NMEA  
GGA, VTG  
or RMC  
19200 8-N-1 10hz  
or RGL 500  
(LB-5 for  
Raven)  
manufactured  
50166, or  
30945 plus  
50581  
LB-3, LB-4,  
and LB-5  
Starlink  
NMEA  
NMEA  
GGA, VTG  
or RMC  
19200 8-N-1 10hz  
YM2000  
Yield  
Ag Leader  
GGA, VTG  
4800  
8-N-1 1 Hz  
39903 plus  
50581  
1
Monitor  
PF3000 Yield Ag Leader  
Monitor  
NMEA  
NMEA  
GGA, VTG  
GGA, VTG  
4800  
4800  
8-N-1 1 Hz  
8-N-1 1 Hz  
39903 plus  
50581  
1
PF3000Pro  
Monitor  
without  
Ag Leader  
39903 plus  
50581  
internal GPS  
2
AFS Yield  
Monitor  
Case-IH  
(Ag Leader  
YM2000)  
NMEA  
GGA, VTG  
GGA, VTG  
4800  
4800  
8-N-1 1 Hz  
8-N-1 1 Hz  
32609 plus  
50581  
AFS Yield  
Monitor  
Case-IH YMIU NMEA  
(yield monitor  
interface unit)  
manufactured  
by Ag Leader  
32609 plus  
50581  
for Case-IH  
GreenStar  
Yield  
Monitor  
John Deere  
NMEA  
NMEA  
GGA, GSA, 4800  
RMC  
8-N-1 1 Hz  
8-N-1 1 Hz  
34189 plus  
50581  
3
New Holland New Holland  
Yield  
Monitor  
GGA, VTG  
4800  
39903 plus  
50581  
(Ag Leader  
PF3000)  
AgGPS 252 Receiver User Guide 59  
 
                   
B
Third-Party Interface Requirements  
Table B.2  
Hardware  
Third-party hardware interface requirements (continued)  
Company  
Protocol NMEA  
messages  
Baud  
Other Pos  
rate  
Cable P/N  
VCD (Vision  
Display  
Controller)  
Rockwell  
NMEA  
NMEA  
NMEA  
NMEA  
GGA, GLL,  
VTG, ZDA  
4800  
8-N-1 1 Hz  
50166, or  
30945 plus  
50581  
Swath XL  
Midtech  
Claus  
GGA  
GGA  
19200 8-N-1 5 Hz  
50166, or  
30945 plus  
50581  
Caterpillar  
Cebis Yield  
Monitor  
4800or 8-N-1 1 Hz  
9600  
50166, or  
30945 plus  
50581  
AGCO  
FieIdStar  
Yield  
AGCO  
GGA, VTG, 4800  
GSV, GSA  
8-N-1 1 Hz  
39903 plus  
50581  
4
Monitor  
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.  
60 AgGPS 252 Receiver User Guide  
 
         
Index  
ASCII input 6  
Autopilot, connecting to 21, 24  
Numerics  
1 PPS output 7  
A
accuracy 4, 10  
adapter cable 21  
Ag Navigator 58  
SiteNet radio 21  
Caterpillar Cebis Yield Monitor 60  
centimeter-level accuracy 10  
changing  
troubleshooting 44  
AgView 57  
Aim Navigator 58  
altitude 13  
battery 43  
AMS 58  
antenna  
correction source 29  
port setting and protocol 33  
characteristics 53  
electrical interference 20  
location of 19  
Class A digital device, FCC notice iii  
mounting 20  
AgGPS 252 Receiver User Guide 61  
 
 
Index  
CMR  
enhancements 18  
COM port 44  
components 18  
environmental conditions for receiver 20  
ephemeris (satellite history) file 13  
European Geostationary Navigation Overlay  
configuring  
RTK 31  
connectors 6  
specification 53  
Contour 58  
Controller Area Network bus protocol see  
CAN bus protocol  
convergence 12  
factory defaults 43  
Falcon 58  
Federal Aviation Administration website 11  
Field Rover 57  
Field Worker Pro 57  
FieldLink DOS 57  
D
FieldLink Windows 57  
data/power cable 6  
Declaration of Conformity iii  
default settings, receiver 56  
Differential GPS (DGPS) positioning  
free corrections 11  
GPS error, sources of 13  
GPS Mode 38  
GPS positioning methods 9  
GPS positions  
E
EGNOS  
output format 7  
output of 14  
accuracy 10  
DGPS, configuring 30  
website 11  
electrical interference, sources of 20  
62 AgGPS 252 Receiver User Guide  
 
GPS reception  
troubleshooting 48  
longitude 13  
Marker 58  
mounting plate assembly 18, 19  
mounting, specification 54  
H
hardware  
third-party 58  
troubleshooting 47  
HGIS 58  
GPS channels 55  
Home screen  
NMEA  
New Holland Yield Monitor 59  
NMEA  
I
information, more 2, 7, 28  
inputs 6  
output 6, 35  
protocol 5  
Instant Survey 58  
ISO 11783 4  
J
HP Differential GPS positioning  
method 9, 10, 11  
satellite beam 39  
troubleshooting 50  
VBS Differential GPS positioning  
method 10, 11  
L
latitude 13  
LB-3, LB-4, LB-5 59  
LED indicator 8  
location of antenna 19  
location of receiver 19  
website 12  
optional extras 18  
AgGPS 252 Receiver User Guide 63  
 
Index  
output 6  
TSIP 5  
overview 3  
P
P-clip 21  
PDOP 13  
Pocket Survey 58  
ports 4  
number of satellites 13  
radio connection 21  
troubleshooting 51  
CAN, ISO 11783 support 7  
setting output rate 35  
troubleshooting (third-party  
positioning method  
power  
release notes 2  
routing cables 22  
RS-232 4, 54, 60  
specification 53  
troubleshooting 47  
protocol  
RTCM  
input 6  
output 6  
CAN bus 7  
NMEA 5  
protocol 5  
website 6  
RTCM 5  
RtkLnk 6  
RTK see Real-Time Kinematic (RTK) GPS  
positioning method  
64 AgGPS 252 Receiver User Guide  
 
RtkLnk protocol 6  
GPS reception 48  
intermittent DGPS 38  
S
satellite history (ephemeris) file 13  
settings 33  
Sitemate 58  
software  
positioning method 51  
receiver location 43  
restoring defaults 43  
RTK 41  
AgRemote 27  
third-party 57  
output 6, 35  
specifications 53  
standard features 4  
Swath Smart 59  
Swath XL 60  
utility  
AgRemote 27  
FlashLoader 200 44  
T
specification 53  
V
vertical accuracy 4  
Vision Display Controller 60  
third-party  
hardware 58  
software 57  
time 13  
time to output positions 43  
Trimble Standard Interface Protocol see TSIP  
Trimble website 1  
AgGPS 252 Receiver User Guide 65  
 
Index  
W
WAAS  
accuracy 10  
warnings  
websites  
NMEA 6  
OmniSTAR 12  
RTCM 7  
SAE International 7  
WAAS 11  
weight, specification 53  
Wide Area Augmentation System see WAAS  
Y
YM2000 Yield Monitor 59  
66 AgGPS 252 Receiver User Guide  
 

Tascam CD Player CD 240 User Manual
Tiger Lawn Mower T6000 User Manual
Toshiba Network Router PA3227E 1ETC User Manual
Toshiba Tablet AT305SE T16 User Manual
TRENDnet Network Hardware TE100 P21 User Manual
Triarch Indoor Furnishings 23174 User Manual
Tripp Lite Surge Protector TR 6FM User Manual
Ultra Products Ventilation Hood ULT31810 User Manual
Vivitar Digital Camera Vivicam 2755 User Manual
Weber Gas Grill Genesis Gold C User Manual