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Ag252_100B_UserGuide_ENG.book Page i Thursday, July 28, 2005 4:06 PM
User Guide
®
AgGPS 252 Receiver
Version 1.00
Revision B
Part Number 55510-00-ENG
August 2005
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Ag252_100B_UserGuide_ENG.book Page ii Thursday, July 28, 2005 4:06 PM Contact Information Nonconforming Product, upon your return of any Nonconforming Product to Trimble in accordance with Trimble Navigation Limited Trimble’s standard return material authorization procedures. Agriculture Business Area 9290 Bond Street, Suite 102 Warranty Exclusions and Disclaimer Overland Park, KS 66214 These warranties shall be applied only in the event and to the USA extent that (i) the Products and Soft
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Ag252_100B_UserGuide_ENG.book Page iii Thursday, July 28, 2005 4:06 PM OF THE POSSIBILITY OF ANY SUCH LOSS AND REGARDLESS OF Europe THE COURSE OF DEALING WHICH DEVELOPS OR HAS This product has been tested and found to comply with the DEVELOPED BETWEEN YOU AND TRIMBLE. BECAUSE SOME requirements for the European Directive 75/322/EEC as STATES AND JURISDICTIONS DO NOT ALLOW THE EXCLUSION amended by 2000/2/EC thereby satisfying the requirements OR LIMITATION OF LIABILITY FOR CONSEQUENTIAL O
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Ag252_100B_UserGuide_ENG.book Page iv Thursday, July 28, 2005 4:06 PM
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Ag252_100B_UserGuide_ENG.book Page v Thursday, July 28, 2005 4:06 PM Contents 1 Introduction . . . . . . . . . . . . . . . . . . . . . . . 1 Warnings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2 Related Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2 Technical Assistance . . . . . . . . . . . . .
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Ag252_100B_UserGuide_ENG.book Page vi Thursday, July 28, 2005 4:06 PM Contents Connectors and Pinouts. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 Port A . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 Port B . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 4 Configuring the Receiver .
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Ag252_100B_UserGuide_ENG.book Page 1 Thursday, July 28, 2005 4:06 PM CHAPTER 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 Syst
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Ag252_100B_UserGuide_ENG.book Page 2 Thursday, July 28, 2005 4:06 PM 1 Introduction 1.1 Warnings Always follow the instructions that accompany a warning. WARNING – Indicates a potential hazard or unsafe practice that could C 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 As
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Ag252_100B_UserGuide_ENG.book Page 3 Thursday, July 28, 2005 4:06 PM CHAPTER 2 Overview 2 In this chapter: Standard Features of the AgGPS 252 Receiver Receiver Connections Receiver Input/Output LED Indicator GPS Positioning Methods 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
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Ag252_100B_UserGuide_ENG.book Page 4 Thursday, July 28, 2005 4:06 PM 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 2.5cm (0.98in) + 2ppm, 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 fou
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Ag252_100B_UserGuide_ENG.book Page 5 Thursday, July 28, 2005 4:06 PM 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 receiv
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Ag252_100B_UserGuide_ENG.book Page 6 Thursday, July 28, 2005 4:06 PM 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 receive
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Ag252_100B_UserGuide_ENG.book Page 7 Thursday, July 28, 2005 4:06 PM Overview 2 – 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. •
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Ag252_100B_UserGuide_ENG.book Page 8 Thursday, July 28, 2005 4:06 PM 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 Solid Normal operation: computing DGPS positions Green Slow No DGPS corrections: computing DGPS posit
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Ag252_100B_UserGuide_ENG.book Page 9 Thursday, July 28, 2005 4:06 PM 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 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 p
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Ag252_100B_UserGuide_ENG.book Page 10 Thursday, July 28, 2005 4:06 PM 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 2sigma. Table 2.4 Absolute accuracy of GPS positioning methods GPS positioning Corrections used Approximate absolute accuracy method Real-Time Kinematic Trimble CMR corrections 2.5 cm (0.98 in) + 2 ppm horizontal (RTK) GPS broadcast by a local accuracy, base station 3.7 cm
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Ag252_100B_UserGuide_ENG.book Page 11 Thursday, July 28, 2005 4:06 PM 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 at www.trimble.com/gps/ 25.2 Differential GPS positioning (DGPS) For differential positioning, the AgGPS 252 receiver uses corrections from WAAS/EGNOS sa
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Ag252_100B_UserGuide_ENG.book Page 12 Thursday, July 28, 2005 4:06 PM 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 i
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Ag252_100B_UserGuide_ENG.book Page 13 Thursday, July 28, 2005 4:06 PM 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 Factors that influence the accuracy of GPS positions Condition Optimum Description value Atmospheric GPS signals are degraded as they travel through the effects ionosphere. The error in
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Ag252_100B_UserGuide_ENG.book Page 14 Thursday, July 28, 2005 4:06 PM 2 Overview Table 2.5 Factors that influence the accuracy of GPS positions (continued) Condition Optimum Description value Minimum > 10 Satellites that are low on the horizon typically produce weak elevation and noisy signals and are more difficult for the receiver to track. Satellites below the minimum elevation angle are not tracked. Multipath Low Multipath errors are caused when GPS signals are reflected off envir
