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BD910
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Trimble BD910 User Manual

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USER GUIDE
Trimble BD910
GNSS Receiver Module
Version 4.82 Revision A November 2013
1
Corporate Office
www.trimble.com/gnss-inertial
Email: GNSSOEMSupport@trimble.com
Legal Notices
© 2006–2013, TrimbleNavigationLimited. All rightsreserved. Trimble andtheGlobe & Triangle logo aretrademarks of Trimble NavigationLimited, registeredinthe UnitedStates and inother countries. CMR+, EVEREST, Maxwell, and Zephyr are trademarks of Trimble Navigation Limited. Microsoft,InternetExplorer,Windows,and Windows Vista are either registered trademarks ortrademarks ofMicrosoft Corporationin the United Statesand/orothercountries. All othertrademarks are the property of theirrespective owners. Support for Galileo is developed under a license oftheEuropean Union and the European Space Agency (BD910/BD920/BD930/BD970/BD982/BX982).
Release Notice
This is the November 2013 release (RevisionA) of theBD910GNSS ReceiverModuleUser Guide. It applies to version 4.82 of thereceiver firmware.
LIMITED WARRANTY TERMS AND CONDITIONS
Product Li mited Warranty
Subjecttothe following terms andconditions, TrimbleNavigation Limited (“Trimble”)warrants that for a period of one(1) year from date of purchase (exceptthe BD970 which is warrantedfor18 months),this Trimble product (the “Product”) will substantially conformto Trimble's publicly available specifications for the Product andthatthe hardware and any storage media components ofthe Product will be substantially free from defects in materials andworkmanship.
Product Software
Productsoftware, whetherbuilt into hardwarecircuitry as firmware, provided as a standalone computersoftware product,embeddedin flash memory,orstoredonmagnetic or othermedia,is licensed solely for use withoras anintegralpartof the Product andis not sold. If accompanied by a separate enduser licenseagreement (“EULA”),use ofany such software will be subject to the terms of suchenduser license agreement (includingany differing limitedwarranty terms, exclusions, and limitations), which shall control overthe terms and conditions set forthin thislimited warranty.
Software Fixes
During the limitedwarranty period you will be entitledtoreceive such Fixes to the Product software that Trimble releases andmakes commercially available and forwhich it does not charge separately, subject to the procedures for delivery topurchasers of Trimble products generally. If you have purchased the Productfrom an authorized Trimble dealer ratherthan from Trimbledirectly, Trimblemay, atits option,forward the software Fixto the Trimbledealer for final distributionto you. MinorUpdates, MajorUpgrades, new products, or substantially new software releases, as identified by Trimble, are expressly excluded from this update process and limitedwarranty. Receipt of software Fixesor otherenhancements shall not serve to extendthelimited warranty period. For purposes ofthiswarranty thefollowing definitions shall apply: (1) “Fix(es)” means an errorcorrectionorotherupdate created to fix a previous software version that does not substantially conform to its Trimble specifications; (2)“MinorUpdate” occurs when enhancements are made tocurrentfeaturesin a software program; and(3) “Major Upgrade”occurs when significantnew features areadded to software, orwhen a newproductcontaining new features replaces the further developmentof a currentproductline. Trimble reserves therightto determine,in its sole discretion,what constitutes a Fix,MinorUpdate, or Major Upgrade.
Warranty Remedies
If theTrimble Product fails during the warranty periodforreasons coveredby this limitedwarranty and you notify Trimble of suchfailure during the warranty period,Trimble will repairOR replace the nonconforming Productwith new, equivalent to new, or reconditioned partsorProduct,OR refundthe Product purchase price paid by you,at Trimble’s option, uponyour return of theProductin accordance with Trimble's product returnprocedures then in effect.
How to Obtain Warranty Service
To obtain warranty service for the Product, please contactyour local Trimble authorized dealer. Alternatively, youmay contactTrimble to request warranty service by e-mailing yourrequest to
GNSSOEMSupport@trimble.com. Please beprepared to provide:
– yourname, address,and telephone numbers – proof of purchase – a copy of this Trimble warranty – a descriptionof the nonconforming Productincluding themodel number – an explanation of the problem The customerservice representative may needadditionalinformation fromyou depending on the nature of the problem.
Warranty Exclusions or Di sclaimer
This Product limitedwarranty shallonly apply inthe event andtothe extentthat (a) the Product is properly and correctly installed,configured, interfaced,maintained, stored, and operated in accordancewith Trimble's applicable operator's manual andspecifications, and; (b) the Productis not modifiedormisused. This Productlimited warranty shall notapply to, and Trimble shall not be responsible for, defects or performance problems resulting from (i)thecombinationorutilizationof theProduct withhardware orsoftware products,information,data, systems, interfaces,ordevices not made, supplied,or specified by Trimble; (ii) the operationof theProductunderany specification other than,or inadditionto,Trimble's standard specifications for its products; (iii) the unauthorized installation,modification, or use ofthe Product; (iv) damage causedby: accident, lightning orotherelectrical discharge,fresh orsalt water immersionorspray (outsideof Productspecifications); or exposure to environmentalconditions forwhich the Product is not intended; (v) normal wear andtear on consumable parts (e.g., batteries); or(vi) cosmeticdamage. Trimbledoes not warrantor guarantee the resultsobtained throughthe use ofthe Product,orthat software components will operate errorfree.
NOTICE REGARDING PRODUCTS EQUIP PED WITH TECHNOLOGY CAPABLE OF TRACKING SATELLITE SIGNALS FROM SATELLITE BASED AUGMENTATION SYSTEMS (SBAS) (WAAS/EGNOS, AND MSAS), OMNISTAR, GPS, MODERNIZED GPS OR GLONASS SATELLITES, O R FROM IALA BEACON SOURCES: TRIMBLE IS
NOT R ESPONSIBL E FOR THE OPERATION O R FAILU RE OF O PERATION O F ANY
SATELLITE BASED POSITIONING SYSTEM OR THE AVAILABILITY O F ANY SATELLITE BASED POSITIONING SIGNALS.
THE FOREGOING LIMITED WARRANTY TERMS STATE TRIMBLE’S ENTIRE LIABILITY,AND YOUR EXCLUSIVE REMEDIES, RELATING TO THE TRIMBLE PRODUCT. EXCEPT AS OTHERWISE EXPRESSLY PROVIDED HEREIN,THE PRODUCT,AND ACCOMPANYING DOCUMENTATION AND MATERIALS ARE PROVIDED “AS-IS” AND WITHOUT EXPRESS OR IMPLIED WARRANTY OF ANY KIND,BY EITHER TRIMBLE 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 PRODUCT. BECAUSE SOME STATES AND JURISDICTIONS DO NOT ALLOW LIMITATIONS ON DURATION OR THE EXCLUSION OF AN IMPLIED WARRANTY, THE ABOVE LIMITATION MAY NOT APPLY ORFULLY APPLY TO YOU.
Lim itation of Liability
TRIMBLE'S ENTIRE LIABILITY UNDER ANY PROVISION HEREINSHALL BE LIMITED TO THE AMOUNT PAID BY YOU FOR THE PRODUCT. TO THE MAXIMUM EXTENT PERMITTED BY APPLICABLE LAW, IN NOEVENT SHALL TRIMBLE OR ITS SUPPLIERS BE LIABLE FOR ANY INDIRECT,SPECIAL,INCIDENTAL,OR CONSEQUENTIAL DAMAGE WHATSOEVER UNDER ANY CIRCUMSTANCE ORLEGAL THEORY RELATING IN ANYWAY TO THE PRODUCTS, SOFTWARE AND ACCOMPANYING DOCUMENTATION AND MATERIALS, (INCLUDING, WITHOUT LIMITATION, DA MAGES FOR LOSS OF BUSINESS PROFITS, BUSINESS INTERRUPTION, LOSS OF DATA, OR ANY OTHER PECUNIARY LOSS),REGARDLESS OF WHETHER TRIMBLE HA S BEEN ADVISED OF THE POSSIBILITY OF ANY SUCH LOSS AND REGARDLESS OF THE COURSE OF DEA LING WHICH DEVELOPS OR HAS DEVELOPED BETWEEN YOU AND TRIMBLE. BECAUSE SOME STATES AND JURISDICTIONS DO NOT
2 BD910 GNSS Receiver Module User Guide
ALLOW THE EXCLUSION OR LIMITA TION OF LIABILITY FOR CONSEQUENTIAL OR INCIDENTAL DAMAGES, THE ABOVE LIMITATION MAY NOT APPLY ORFULLY APPLY TO YOU.
PLEASE N OTE: THE ABOVE TRIMBLE LIMITED WARRANTY PROVISIONS WILL NOT AP PLY TO P RODUC TS PUR CHASED IN THOSE JURISDICTIONS (E.G., MEMBER STATES OF THE EURO PEAN EC ONOMIC AREA) IN W HICH PRODUC T WARRANTIES ARE THE RESPON SIBILITY OF THE LOCAL TRIMBLE AUTHORIZED DEALER FROM WHOM THE PRODUC TS ARE ACQU IRED. IN SUC H A CASE, PLEASE C ONTACT YOU R LOCAL TRIMBLE AU THORIZED DEALER FO R APPL ICABLE W ARRANTY INFORMATION.
Official Language
THE OFFICIAL LANGUAGE OF THESE TERMS AND CONDITIONS IS ENGLISH. IN THE EVENT OF A CONFLICT BETWEEN ENGLISH AND OTHER LANGUAGE V ERSIONS, THE ENGLISH LANGUAGE SHALL CONTROL.
COCOM limits
This noticeappliesto the BD910,BD920,BD930, BD960,BD970,BD982, BX960,BX960-2,and BX982 receivers. The U.S. Department of Commerce requires that allexportableGPS productscontain performance limitations so thatthey cannot be usedin a mannerthat could threatenthesecurity ofthe UnitedStates. The following limitations are implementedon this product: – Immediate access tosatellite measurements andnavigation results is disabledwhenthe receivervelocity is computed to be greaterthan 1,000knots,orits altitude iscomputed to be above 18,000 meters. The receiver GPS subsystem resets untilthe COCOM situation clears. As a result, all logging and stream configurations stop untiltheGPS subsystem is cleared.
Restriction of Use of Certain Hazardous Substances in Electrical
and Electronic Equipment (RoHS)
Trimble products in this guide comply inall materialrespects with DIRECTIVE 2002/95/EC OF THE EUROPEAN PARLIAMENT AND OF THE COUNCIL of27 January 2003 on the restrictionof the use of certain hazardous substances in electrical andelectronicequipment (RoHS Directive) andAmendment2005/618/EC filed under C(2005) 3143, with exemptions for lead insolder pursuanttoParagraph 7 ofthe Annex to theRoHS Directive applied.
Waste Electrical and Electronic Equipment (WEEE)
For product recycling instructions andmore information, please go to www.trimble.com/ev.shtml. Recycling inEurope: To recycle TrimbleWEEE (Waste Electrical and Electronic Equipment,products that run on electricalpower.), Call+31 497 53 24 30, andask forthe “WEEE Associate”. Or,mail a requestforrecycling instructions to: Trimble Europe BV c/o MenloWorldwideLogistics Meerheide45 5521 DZ Eersel,NL
BD910 GNSS Receiver Module User Guide 3
Contents
1 Introduction 6
About the BD910GNSS receiver 7 BD910features 8 Default settings 10 Technicalsupport 10
2 Specifications 11
Positioning specifications 12 Performance specifications 12 Physical and electrical characteristics 13 Environmental specifications 13 Communication specifications 14
3 Electrical System Integration 15
80-pin header connector pinouts 16 1PPS and ASCII time tag 21 ASCII time tag 22 Power input 23 Antenna poweroutput 23 LED control lines 24 Power switch and reset 25 Event 26 Serial port 27 USB 27 Ethernet 28
Isolation transformer selection 28 Ethernet reference design 28 Ethernet design using RJ-45 with integrated magnetics 29 Electrical characteristics 30 Ethernet design using discrete components 30 Ethernet routing 31
Recommended electrical specifications for the antenna 33
4 Mechanical Drawings 34
BD910module mechanical drawing 35 BD910evaluation I/O board 36
Antenna jumper setting 36
BD910PCB assembly schematics 38
PCB layout recommendations 38 PCB assembly recommendations 38
5 Installation 40
BD910 GNSS Receiver Module User Guide 4
Contents
Unpacking and inspecting the shipment 41
Shipment carton contents 41 Reporting shipping problems 41
Installation guidelines 41
Considering environmental conditions 41 Supported antennas 41 Mounting the antennas 42
Sources of electricalinterference 42 Interface board evaluation kit 43 Routing and connecting the antenna cable 44 LED functionality and operation 46
Troubleshooting receiver issues 47
Glossary 49
BD910 GNSS Receiver Module User Guide 5

Introduction

1
In this chapter:
n
About the BD910GNSS receiver
n
BD910features
n
Default settings
n
Technicalsupport
This manual describes how to set up and use the Trimble BD910 GNSS receiver module. The BD910 receiver uses advanced navigation architecture to achieve real-time centimeteraccuracies with minimal latencies.
Even if you have used other GNSS or 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 GNSS or GPS, visit the Trimble website (www.trimble.com).
BD910 GNSS Receiver Module User Guide 6
1 Introduction

About the BD910 GNSS receiver

The receiver is used for a wide range of precise positioning and navigation applications. These uses include unmanned vehicles and port and terminal equipment automation, and any other application requiring reliable, centimeter-level positioning at a high update rate and low latency.
The receiver offers centimeter-levelaccuracy based on carrier phase RTK and submeter accuracy code-based solutions.
Automatic initialization and switching between positioning modes allowfor the best position solutions possible. Low latency (less than 30 msec)and high update rates give the response time and accuracy required for precise dynamic applications.
You can configure the receiver as an autonomous base station (sometimes called a reference station) or as a rover receiver (sometimes called a mobilereceiver). Streamed outputs from the receiver provide detailed information, including the time, position, heading, quality assurance (figure of merit) numbers, and the number of tracked satellites. The receiver also outputs a one pulse per second (1 PPS) strobe signal which lets remote devices precisely synchronize time.
Designed for reliable operation in all environments, the receiver provides a positioning interface to an officecomputer, external processing device, or control system. The receiver can be controlled through a serial, ethernet, or USB port using binary interface commands or the web interface.
BD910 GNSS Receiver Module User Guide 7
1 Introduction

BD910 features

The receiver has the following features:
l
Position antenna based a on 220-channel Trimble Maxwell™6 chip:
ll
GPS: L1 C/A
l
GLONASS: L1 C/A
l
Galileo: E1
l
BeiDou: B1
l
QZSS: L1 C/A, L1 SAIF
l
SBAS: L1 C/A
l
Advanced Trimble Maxwell6 Custom Survey GNSS Technology
l
Very low noise GNSS carrierphase measurements with <1 mm precision in a 1 Hz bandwidth
l
Proven Trimble low elevation tracking technology
l
1 USB port (device only)
l
1 LANEthernet port:
ll
Supports links to 10BaseT/100BaseT networks
l
Allfunctions are performed through a single IP address simultaneously—including web interface access and raw data streaming
l
Network Protocols supported:
ll
HTTP (web GUI)
l
NTP Server
l
NMEA, GSOF, CMR, and so on over TCP/IP or UDP
l
NTripCaster, NTripServer, NTripClient
l
mDNS/UPnP Service discovery
l
Dynamic DNS
l
Email alerts
l
Network link to Google Earth
l
Support for external modems through PPP
l
4 x RS-232 ports (baud rates up to 460,800)
l
1 Hz, 2 Hz, 5 Hz, 10 Hz, and 20 Hz positioning and heading outputs (depending on the installed option)
l
Up to 20 Hz raw measurement and position outputs
BD910 GNSS Receiver Module User Guide 8
1 Introduction
l
Correction inputs/outputs: CMR, CMR+™, sCMRx, RTCM 2.1, 2.2, 2.3, 3.0. Note:
ll
The functionality to input or output any of these corrections depends on the installed options.
l
Different manufacturers may have established different packet structures for their correction messages. Thus, the BD9xx receivers may not receive corrections from other manufacturers receivers, and other manufacturers receivers may not be able to receive corrections from BD9xx receivers.
l
Navigation outputs:
ll
ASCII: NMEA-0183: GBS; GGA; GLL; GNS; GRS; GSA; GST; GSV; HDT; LLQ; PFUGDP; DTM; PTNL,AVR; PTNL,BPQ; PTNL,GGK; PTNL,PJK; PTNL,PJT; PTNL,VGK; PTNL,VHD; RMC; ROT; VTG; ZDA.
l
Binary: Trimble GSOF.
l
Control software: HTML Web browser (Google Chrome (recommended), Internet Explorer®, Mozilla Firefox, Apple Safari, Opera)
l
1 Pulse Per Second Output
l
Event Marker Input Support
l
LED drive support
l
Supports Fault Detection and Exclusion (FDE), Receiver Autonomous Integrity Monitoring (RAIM)
Note – Galileo support is developed under a license of the European Union and the European Space Agency.
Note – At the time of this publication, no public BeiDou ICD was available. The current capability in the receiver is based on publicly available information. As such, Trimble cannot guarantee that these receivers will be fully compatible with a future generation of BeiDou satellites or signals.
BD910 GNSS Receiver Module User Guide 9
1 Introduction

Default settings

Allsettings are stored in application files. The default application file, Default.cfg, is stored permanently in the receiver, and contains the factory default settings. Whenever the receiver is reset to its factory defaults, the current settings (stored in the current application file, Current.cfg) are reset to the values in the default application file.
These settings are defined in the default application file.
Function Settings Factory default
SV Enable - AllSVs enabled GeneralControls Elevation mask 10°
PDOP mask 99 RTK positioning mode Low Latency Motion Kinematic
Ports Baud rate 38,400
Format 8-None-1
Flow control None Input Setup Station Any NMEA/ASCII (all supported messages) Allports Off Streamed Output All types Off
Offset=00 RT17/Binary Allports Off Reference Position Latitude 0°
Longitude 0° Altitude 0.00m HAE
Antenna Type Unknown
Height (true vertical) 0.00m Measurement method Antenna Phase Center
1PPS Disabled

Technical support

If you have a problem and cannot find the information you need in the product documentation, send an email to GNSSOEMSupport@trimble.com.
Documentation, firmware, and software updates are available at: www.trimble.com/gnss-
inertial/GNSS-Positioning-and-Heading-Systems.aspx.
BD910 GNSS Receiver Module User Guide 10

Specifications

2
In this chapter:
n
Positioning specifications
n
Performance specifications
n
Physical and electrical characteristics
n
Environmental specifications
n
Communication specifications
This chapter details the specifications for the receiver.
Specifications are subject to change without notice.
BD910 GNSS Receiver Module User Guide 11
2 Specifications

Positioning specifications

Note – The following specifications are provided at 1 sigma level when using a Trimble Zephyr 2 antenna. These specifications may be affected by atmospheric conditions, signal multipath, and satellite geometry. Initialization reliability is continuously monitored to ensure highest quality.
Feature Specification
Initialization time Typically <1 minute Initialization accuracy >99.9%
Mode Accuracy Latency (at max. output rate) Maximum Rate
Single Baseline RTK (<5km)
0.008 m + 1 ppm horizontal <30ms 20 Hz
0.15m + 1 ppm vertical
DGPS 0.25 m + 1 ppm horizontal <20ms 20 Hz
0.5 m + 1 ppm vertical
1
SBAS
0.5 m horizontal <20ms 20 Hz
0.85m vertical

Performance specifications

Note – The Time to First Fix specifications are typical observed values. A cold start is when the receiver has no previous satellite (ephemerides/almanac) or position (approximate position or time) information. A warm start is when the ephemerides and last used position is known.
Feature Specification
Time to First Fix (TFF) Cold Start <45seconds
Warm Start <30seconds Signal Re-acquisition <2 seconds
Velocity Accuracy
Maximum Operating Limits
Acceleration 11g
2
Horizontal 0.007 m/sec Vertical 0.020 m/sec
3
Velocity 515m/sec Altitude 18,000 m
1
GPS only and depends on SBAS system performance. FAA WAASaccuracy specifications are <5m 3DRMS.
2
1 sigma level when using a Trimble Zephyr 2 antenna. These specifications may be affected by atmospheric conditions, signal multipath, and satellite
geometry.Initialization reliabilityis continuously monitored to ensure highest quality.
3
As required by the US Department of Commerce to comply with export licensing restrictions.
BD910 GNSS Receiver Module User Guide 12
2 Specifications

Physical and electrical characteristics

Feature Specification
Dimensions (L x W x H) 41 mm x 41 mm x 7 mm Power 3.3 V DC +5%/-3%
Typical 1.1 W (L1GPS + L1 GLONASS) Weight 19 grams Connectors I/O: 80-pin Narrow Pitch Panasonic (AXK780327G) Socket Panasonic
AXK880125WG required mating connector (Rated 50 cycles)
Antenna: MMCX receptacle(Rated for 500 cycles) Antenna LNA Power Output Output voltage: 3.3 to 5 V DC
Current rating: 200mA Maximum current: 400mA
Minimum required LNAgain 24.5dB

Environmental specifications

Feature Specification
Temperature Operating: -40°C to 85°C (-40°F to 185°F)
Storage: -55°C to 85°C (-67°F to 185°F)
Vibration MIL810F, tailored
Random 6.2 gRMS operating Random 8 gRMS survival
Mechanical shock MIL810D
+/- 40g operating +/- 75g survival
Operating humidity 5% to 95%R.H. non-condensing, at +60°C (140°F)
BD910 GNSS Receiver Module User Guide 13
2 Specifications

Communication specifications

Feature Specification
l
Communications 1 LANport
4 x RS-232 ports Baud rates up to 460,800
1 USB 2.0 port Receiver position update rate 1 Hz, 2 Hz, 5 Hz, 10 Hz, and 20 Hz positioning Correction data input CMR, CMR+™, sCMRx, RTCM 2.0–2.3, RTCM 3.0, 3.1 Correction data output CMR, CMR+, sCMRx, RTCM 2.0 DGPS (select RTCM 2.1), RTCM 2.1–
2.3, RTCM 3.0
Data outputs 1PPS, NMEA, Binary GSOF, ASCIITime Tags
Supports links to 10BaseT/100BaseT networks.
l
Allfunctions are performed through a single IPaddress simultaneously – including web interface access and data streaming.
BD910 GNSS Receiver Module User Guide 14

Electrical System Integration

In this chapter:
n
80-pin header connector pinouts
n
1PPS and ASCII time tag
n
ASCII time tag
n
Power input
n
Antenna poweroutput
n
LED control lines
3
n
Power switch and reset
n
Event
n
Serial port
n
USB
n
Ethernet
n
Recommended electrical specifications for the antenna
BD910 GNSS Receiver Module User Guide 15
3 Electrical System Integration

80-pin header connector pinouts

The 80-pin Narrow Pitch Panasonic Socket has the following pinouts.
Pin Signal name Description Integration notes
1 VCC Input DC Card
power
2 VCC Input DC Card
power
3 ANTENNA_POWER VCC Input DC Card power
4 Power LED POWER Indicator. High when
5 RESET_IN RESET_IN - ground to reset Drive low to reset the unit. Otherwise, leave
6 RTK LED RTK LED. Flashes when an
7 GND Ground Digital Ground Ground Digital Ground 8 Satellite Satellite LED. Rapid flash
9 NO_CONNECT RESERVED For proper operation of the receiver, do not
10 NO_CONNECT RESERVED For proper operation of the receiver, do not
VCC Input DC Card power (3.3V only)
VCC Input DC Card power (3.3V only)
(3.3V to 5V)
unit is on, low when off. This is similar to all BD9xx products, except for the requirement for an external resistor. This allows user to use this as a control line.
RTK correction is present. This is similar to all BD9xx products, except for the requirement for an external resistor.
indicates <5 satellites. Slow flash indicates >5 satellites.
VCC Input DC Card power (3.3V only)
VCC Input DC Card power (3.3V only)
This feeds antenna power. Voltage and current requirement based on antenna voltage used. Ripple Voltage should be 100mV Vpp or better. This can be shorted directly to 3.3V used to supply power to the unit if the antenna can handle 3.3V. It can handle a maximum current of 400 mA.
When used to drive an LED, a series resistor with a typical value of 300 Ohms is required. This pin supplies a maximum current of 4mA. For LEDs with Vfabove 2.7 or current excess of 4mA, an external buffer is required.
unconnected. When used to drive an LED, a series resistor
with a typical value of 300 Ohms is required. This pin supplies a maximum current of 4mA. For LEDs with Vfabove 2.7 or current excess of 4mA, an external buffer is required.
When used to drive an LED, a series resistor with a typical value of 300 Ohms is required. This pin supplies a maximum current of 4mA. For LEDs with Vfabove 2.7 or current excess of 4mA, an external buffer is required.
connect anything to this pin. This pin can be left floating since the receiver does not support USB in a host mode.
connect anything to this pin. Reserved for internal use.
BD910 GNSS Receiver Module User Guide 16
3 Electrical System Integration
Pin Signal name Description Integration notes
11 NO_CONNECT RESERVED For proper operation of the receiver, do not
connect anything to this pin. Reserved for internal use.
12 NO_CONNECT RESERVED For proper operation of the receiver, do not
connect anything to this pin. Reserved for internal use.
13 BOOT_MONITOR* Boot to Monitor pin. This
prevents the unit from executing the application
Drive the pin low at boot up to force the receiver into monitor mode.
Do not connect for normal operation.
firmware.
14 NO_CONNECT RESERVED For proper operation of the receiver, do not
connect anything to this pin. Reserved for internal use.
15 NO_CONNECT RESERVED For proper operation of the receiver, do not
connect anything to this pin. Reserved for internal use.
16 NO_CONNECT RESERVED For proper operation of the receiver, do not
connect anything to this pin. Reserved for
internal use. 17 GND Ground DigitalGround Ground Digital Ground 18 COM2_Rx COM 2 Receive Data - TTL
Level
Connect COM2_RX to a transceiver if RS-232
levelis required.
Note – This pin is connected to two physical pins.
19 COM2_CTS COM 2 Clear to Send - TTL
Level
20 COM2_Tx COM 2 Transmit Data - TTL
Level
Connect COM2_CTS to a transceiver if RS-232
levelis required.
Note – This pin is connected to two physical pins.
Connect COM2_TX to a transceiver if RS-232
levelis required. 21 COM2_RTS COM 2 Request to Send Request to Send for COM 2 connect to a
transceiver if RS-232 level is required. 22 COM1_Tx COM 1 Transmit Data – TTL
Level
Connect COM1_TX to a transceiver if RS-232
levelis required. 23 GND Ground DigitalGround Ground Digital Ground 24 COM1_Rx COM 1 Receive Data – TTL
Level
25 USB D (-) USB D (-)Bi-directional USB
interface data (-)
Connect COM1_RX to a transceiver if RS-232
levelis required.
Device Mode only. If VCC is supplied, USB
detects VBUS. 26 GND Ground DigitalGround Ground Digital Ground 27 USB D (+) USB D (+) Bi-directional USB
interface data (+)
Device Mode only. If VCC is supplied, USB
detects VBUS.
BD910 GNSS Receiver Module User Guide 17
3 Electrical System Integration
Pin Signal name Description Integration notes
28 GND Ground DigitalGround Ground Digital Ground 29 GND Ground DigitalGround Ground Digital Ground 30 PPS (Pulse per
Second)
Pulse per second This is 3.3V TTLlevel, 4mA max drive
capability. To drive 50Ohm load to ground,
an external bufferis required. PPS Jitter spec
is 7nS. 31 NO_CONNECT RESERVED For proper operation of the receiver, do not
connect anything to this pin. Reserved for
internal use. 32 NO_CONNECT RESERVED For proper operation of the receiver, do not
connect anything to this pin. Reserved for
internal use. 33 NO_CONNECT RESERVED For proper operation of the receiver, do not
connect anything to this pin. Reserved for
internal use. 34 NO_CONNECT RESERVED For proper operation of the receiver, do not
connect anything to this pin. Reserved for
internal use. 35 GND Ground DigitalGround Ground Digital Ground 36 NO_CONNECT RESERVED For proper operation of the receiver, do not
connect anything to this pin. Reserved for
internal use. 37 Event1 Event1 - Input Event1 (must be 3.3V TTL level) 38 NO_CONNECT RESERVED For proper operation of the receiver, do not
connect anything to this pin. Reserved for
internal use. 39 Event2 Event2 - Input Event2 (must be 3.3V TTL level) 40 NO_CONNECT RESERVED For proper operation of the receiver, do not
connect anything to this pin. Reserved for
internal use. 41 GND Ground DigitalGround Ground Digital Ground 42 GND Ground DigitalGround Ground Digital Ground 43 NO_CONNECT RESERVED For proper operation of the receiver, do not
connect anything to this pin. Reserved for
internal use. 44 NO_CONNECT RESERVED For proper operation of the receiver, do not
connect anything to this pin. Reserved for
internal use. 45 NO_CONNECT RESERVED For proper operation of the receiver, do not
connect anything to this pin. Reserved for
internal use.
BD910 GNSS Receiver Module User Guide 18
3 Electrical System Integration
Pin Signal name Description Integration notes
46 NO_CONNECT RESERVED For proper operation of the receiver, do not
connect anything to this pin. Reserved for
internal use. 47 GND Ground DigitalGround Ground Digital Ground 48 NO_CONNECT RESERVED For proper operation of the receiver, do not
connect anything to this pin. Reserved for
internal use. 49 NO_CONNECT RESERVED For proper operation of the receiver, do not
connect anything to this pin. Reserved for
internal use. 50 NO_CONNECT RESERVED For proper operation of the receiver, do not
connect anything to this pin. Reserved for
internal use. 51 NO_CONNECT RESERVED For proper operation of the receiver, do not
connect anything to this pin. Reserved for
internal use. 52 NO_CONNECT RESERVED For proper operation of the receiver, do not
connect anything to this pin. Reserved for
internal use. 53 NO_CONNECT RESERVED For proper operation of the receiver, do not
connect anything to this pin. Reserved for
internal use. 54 NO_CONNECT RESERVED For proper operation of the receiver, do not
connect anything to this pin. Reserved for
internal use. 55 NO_CONNECT RESERVED For proper operation of the receiver, do not
connect anything to this pin. Reserved for
internal use. 56 COM4_CTS COM 4 Clear to Send - TTL
Level
Connect COM4_CTS to a transceiver if RS-232
levelis required. 57 NO_CONNECT RESERVED For proper operation of the receiver, do not
connect anything to this pin. Reserved for
internal use. 58 COM4_RTS COM 4 Request to Send - TTL
Level
Request to Send for COM 4 connect to a
transceiver if RS-232 level is required. 59 NO_CONNECT RESERVED For proper operation of the receiver, do not
connect anything to this pin. Reserved for
internal use. 60 COM3_Rx COM 3 Receive Data – TTL
Level
Connect COM3_RX to a transceiver if RS-232
levelis required. 61 NO_CONNECT RESERVED For proper operation of the receiver, do not
BD910 GNSS Receiver Module User Guide 19
3 Electrical System Integration
Pin Signal name Description Integration notes
connect anything to this pin. Reserved for
internal use. 62 COM3_Tx COM 3 Transmit Data – TTL
Level
63 COM4_Rx COM 4 Receive Data – TTL
Level
64 COM4_Tx COM 4 Transmit Data – TTL
Level
Connect COM3_TX to a transceiver if RS-232
levelis required.
Connect COM4_RX to a transceiver if RS-232
levelis required.
Connect COM4_TX to a transceiver if RS-232
levelis required. 65 GND Ground DigitalGround Ground Digital Ground 66 GND Ground DigitalGround Ground Digital Ground 67 GND Ground DigitalGround Ground Digital Ground 68 GND Ground DigitalGround Ground Digital Ground 69 ETH_RD+ Ethernet Receive line plus.
Connect to Magnetics RD+
Differentialpair. 70 GND Ground DigitalGround Ground Digital Ground 71 ETH_RD- Ethernet Receive line minus.
Connect to Magnetics RD-
Differentialpair. 72 GND Ground DigitalGround Ground Digital Ground 73 GND Ground DigitalGround Ground Digital Ground 74 I/O_READY I/O status ready This pin indicates that the signal lines can
now be drive. For proper operation of the receiver, do not connect anything to this pin. Reserved for internal use.
75 ETH_TD+ Ethernet Transmit line plus.
Connect to Magnetics TD+
Differentialpair. 76 GND Ground DigitalGround Ground Digital Ground 77 ETH_TD- Ethernet Transmit line
Connect to Magnetics TD-
minus. Differential pair. 78 GND Ground DigitalGround Ground Digital Ground 79 GND Ground DigitalGround Ground Digital Ground 80 DO NOT CONNECT Reserved DO NOT CONNECT
BD910 GNSS Receiver Module User Guide 20
3 Electrical System Integration

1PPS and ASCII time tag

The receiver can output a 1 pulse-per-second (1PPS) time strobe and an associated time tag message. The time tags are output on a user-selected port.
The leading edge of the pulse coincides with the beginning of each UTC second. The pulse is driven between nominal levels of 0.0 V and 3.3 V (see below). The leading edge is positive (rising from 0 V to
3.3 V). The receiver PPS out is a 3.3 V TTL level with a maximum source/sink current of 4 mA. If the system requires a voltage level or current source/sink level beyond these levels, you must have an external buffer. This line has ESD protection.
The illustration below shows the time tag relation to 1PPS wave form:
The pulse is about 8 microseconds wide, with rise and falltimes of about 100nsec. Resolution is approximately 40 nsec, where the 40 nsec resolution means that the PPS shifting mechanism in the receiver can align the PPS to UTC/GPS time only within +/- 20 nsec, but the following external factor limits accuracy to approximately ±1 microsecond:
l
Antenna cable length Each meter of cable adds a delay of about 2 nsec to satellite signals, and a corresponding delay
in the 1PPS pulse.
BD910 GNSS Receiver Module User Guide 21
3 Electrical System Integration

ASCII time tag

Each time tag is output about 0.5 second before the corresponding pulse. Time tags are in ASCII format on a user-selected serialport. The format of a time tag is:
UTC yy.mm.dd hh:mm:ss ab
Where:
l
UTC is fixed text.
l
yy.mm.dd is the year, month, and date.
l
hh:mm:ss is the hour (on a 24-hour clock), minute, and second. The time is in UTC, not GPS.
l
a is an integer number representing the position-fix type: 1 = time solution only 2 = 1D position and time solution 3 = currently unused 4 = 2D position and time solution 5 = 3D position and time solution
l
b is the number of GNSS satellites being tracked. If the receiver is tracking 9 or more satellites, b will always be displayed as 9.
l
Each time tag is terminated by a carriage return, line feed sequence. A typical printout looks like:
UTC 02.12.21 20:21:16 56 UTC 02.12.21 20:21:17 56 UTC 02.12.21 20:21:18 56
Note – If the receiver is not tracking satellites, the time tag is based on the receiver clock. In this case, a and b are represented by “??”. The time readings from the receiver clock are less accurate than time readings determined from the satellite signals.
BD910 GNSS Receiver Module User Guide 22
3 Electrical System Integration

Power input

Item Description
Power requirement The unit, excluding the antenna, operates at 3.3 V +5%/-3%. The 3.3 V
should be able to supply 1 A of surge current. The typicalpower consumption based on band usage is:
l
L1 GPS + L1 GLONASS = 1.1 W

Antenna power output

Item Description
Power output specification
Short-circuit protection
The antenna DC poweris supplied directly from Pin 3 on the Multipin Interface Connector J5. The antenna output is rated to a maximum voltage of 10Vdc and can source a maximum of 400mAmps.
Power is a separate pin and it can be powered externally or shorted to the input power if the antenna can handle 3.3 V. This pin can handlea maximum supply of 100mA at 5V.
The unit does not have over-current / short circuit protection related to antenna bias. Short circuits may cause damage to the antenna port bias filtering components if the sourcing supply is not current limited to less than 400mA.
BD910 GNSS Receiver Module User Guide 23
3 Electrical System Integration

LED control lines

Item Description
Driving LEDs
The outputs are 3.3V TTL levelwith a maximum source/sink current of 4mA. An externalseries resistor must be used to limit the current. The value of the series resistor in Ohms is determined by:
(3.3-Vf)/(If)> Rs > (3.3 V -Vf)/(.004) Rs = Series resistor If = LED forward current, max typical If of the LED should be less than 3mA Vf = LED forward voltage, max typicalVf of the LED should be less than 2.7V Most LEDs can be driven directly as shown in the circuit below:
LEDs that do not meet If and Vf specification must be driven with a buffer to
ensure proper voltage level and source/sink current. Power LED This active-high line indicates that the unit is powered on. Satellite LED
RTK Correction A slow flash indicates that the unit is receiving corrections. This will also flash
This active-high line indicates that the unit has acquired satellites.
A rapid flash indicates that the unit has less than 5 satellites acquired while a
slow flash indicates greater than 5 satellites acquired. This line will stay on if
the unit is in monitor mode.
when the unit is in monitor mode.
BD910 GNSS Receiver Module User Guide 24
3 Electrical System Integration

Power switch and reset

Item Description
Reset switch Driving Reset_IN_L, Pin 5, low will cause the unit to reset. The unit will
remain reset at least 300mS after the Reset_In_L is deasserted. The unit
remains powered while in reset. Power Switch Driving Boot_Monitor low while the unit is starting will cause the receiver to
go into the boot monitor. This keeps the application from loading. For
normal operation, keep Boot_Monitor floating.
BD910 GNSS Receiver Module User Guide 25
3 Electrical System Integration

Event

Item Description
Event 1 Pin 37 is dedicated as an Event_In pin.
This is a TTL only input, it is not buffered or protected for any inputs outside of 0Vto 3.3V. It does have ESD protection. If the system requires event to handle a voltage outside this range, the system integrator must condition the signal prior to connecting to the unit.
Event 2 Pin 39 is dedicated as an Event_In pin. This is a TTL only input, it is not
buffered or protected for any inputs outside of 0V to 3.3V. It does have ESD protection but if the system requires event to handle a voltage outside this range, the system integrator must condition the signal prior to connecting the unit.
Trimble recommends adding a Schmitt trigger and ESD protection to the Event_In pin. This prevents any "ringing" on the input from causing multiple and incorrect events to be recognized.
U1 is Texas instrument: SN74LVC2G17 U2 is ONSemiconductor: NUP4301MR6T1G SN74LVC2G17 is also suitable for 5 V systems. It accepts inputs up to 5.5 V even when using 3.3 V
VCC. Take care to make sure that I/O does not exceed 3.3 V. For more information, go to www.trimble.com/OEM_ReceiverHelp/V4.82/default.html#AppNote_
EventInput.html.
BD910 GNSS Receiver Module User Guide 26
3 Electrical System Integration

Serial port

Item Description
COM 1 TTL levelno flowcontrol
COM 2 TTL levelwith flowcontrol
COM 3 TTL levelno flowcontrol
COM 4 TTL levelwith flowcontrol
Com 1 is at 0-3.3V TTL. If the integrator needs this port to be at RS-232level, a proper transceiver powered by the same 3.3V that powers the receiver needs to be added.
For development using the I/O board, this Com port is already connected
to an RS-232transceiver. This is labeled Port 1 on the I/O board. All
TTL-COM willsupport either 3.3v CMOS or TTL levels.
Com 2 is at 0-3.3V TTL. This port has RTS/CTS to support hardware flow control. If the integrator needs this port to be at RS-232 level, a proper transceiver powered by the same 3.3V that powers the receiver needs to be added. For development using the I/O board, this Com port is already connected to an RS-232 transceiver. This is labeled Port 2 on the I/O board. AllTTL-COM will support either 3.3v CMOS or TTL levels.
Com 3 is at 0-3.3V TTL. If the integrator needs this port to be at RS-232level, a proper transceiver powered by the same 3.3V that powers the receiver needs to be added.
For development using the I/O board, this Com port is already connected
to an RS-232transceiver. This is labeled Port 3 on the I/O board. All
TTL-COM willsupport either 3.3v CMOS or TTL levels
Com 4 is at 0-3.3V TTL. This port has RTS/CTS to support hardware flow control. If the integrator needs this port to be at RS-232 level, a proper transceiver powered by the same 3.3V that powers the receiver needs to be added.
For development using the I/O board, this Com port is already connected
to an RS-232transceiver. This is labeled Port 4 on the I/O board. All
TTL-COM willsupport either 3.3v CMOS or TTL levels.
USB
The USB has a built-in PHY. The unit supports USB 2.0 Device configuration at low speed, full speed and high speed configuration. The port has ESD protection; however a USB 2.0 compliant common mode choke located near the connector should be added to ensure EMI compliance.
The BD910only supports USB device mode.
BD910 GNSS Receiver Module User Guide 27
3 Electrical System Integration

Ethernet

The receiver contains the Ethernet MAC and PHY, but requires external magnetics. The PHY layer is based on the MicrelKSZ8041NLI it is set to default to 100Mbps, full duplex with auto-negotiation enabled.
Since the Ethernet functionality will typically increase the receiver power consumption by approximately 10%, the receiver shuts down the Ethernet controller ifno Ethernet devices are connected within 2 minutes.

Isolation transformer selection

Parameters Value Test condition
Turns Ratio 1CT:1CT Open-circuit inductance (min.) 350uH 100 mV, 100kHz, 8 mA Leakage inductance (max.) 0.4 uH 1 MHz (min.) DC resistance (max.) 0.9 Ohms Insertion loss (max.) 1.0dB 0MHz–65MHz HiPot (min. 1500 Vrms

Ethernet reference design

The ethernet interfacecan be implemented using a single part or using discrete components. For more information, see:
l
Ethernet design using RJ-45 with integrated magnetics, page 29
l
Ethernet design using discrete components, page 30
BD910 GNSS Receiver Module User Guide 28
3 Electrical System Integration

Ethernet design using RJ-45 with integrated magnetics

The Ethernet interfacecan be implemented with a single part by using an integrated part like TE Connectivity’s 6605767-1which has magnetics, common mode choke, termination and transient voltage suppression fully integrated in one part.
RJ-45drawing
JX10-0006NL schematic
BD910 GNSS Receiver Module User Guide 29
3 Electrical System Integration

Electrical characteristics

Parameter Specifications
Insertion loss 100kHz 1-125MHz
-1.2 dB max. -0.2–0.002*f
Return loss (Z out = 100 Ohm +/- 15%)
Inductance (OCL) (Media side -40°C + 85°C)
Crosstalk, adjacent channels 1 MHz 10-100MHz
Common mode rejection radio
DC resistance 1/2 winding
DC resistance imbalance
0.1–30 MHz: 30–60 MHz: 60–80 MHz:
350uH min. Measured at 100kHz, 100 mVRMS and with 8
-50 dB min. -50+17*LOG10(f/10) dB min.
2 MHz 30–200MHz
-50 dB min. -15+20*LOG10(f/200)dB min.
0.6 Ohms max.
+/- 0.065 Ohms max. (center tap symmetry)
-16 dB min.
-10+20*LOG (f/60 MHz dB min.)
-10 dB min.
mA DC bias)
^1.4 db max.
10
input - output isolation
1500 Vrms min. at 60 seconds

Ethernet design using discrete components

For maximum flexibility, a system integrator may choose to implement the Ethernet using discrete parts. The design below shows an example of such a design. It includes the Ethernet magnetics, termination of unused lines as wellas surge protection. The magnetics used is a Pulse Engineering HX1188. Surge protection is provided by a Semtech SLVU2.8-4. In order to meet electrical isolation requirements, it is recommended to use capacitors with a greater than 2kV breakdown voltage.
BD910 GNSS Receiver Module User Guide 30
3 Electrical System Integration
Ethernet schematic
Part Reference Value
C4–C6 1000pF 2kV C3 10 uF X5R 6.3V D1 SEMTECH SLVU2.8–4 J1 RJ45 Conn L1, L2 Ferrite Bead R1–R11 49.90402 1% T1 Pulse engineering HX1188

Ethernet routing

The distance from the BD910/BD920connector, the Ethernet connector and the magnetics should be less than 2 inches. The distance from the RJ-45and the magnetics should be minimized to prevent conducted emissions issues. In this design, the chassis ground and signal ground are
BD910 GNSS Receiver Module User Guide 31
3 Electrical System Integration
separated to improve radiated emissions. The integrator may choose to combine the ground. The application note from the IC vendor is provided below for more detailed routing guidelines.
The sample routing below shows a two-layer stack up, with single side board placement. The routing shown below makes sure that the differentialpairs are routed over solid planes.
Top view
Bottom view
BD910 GNSS Receiver Module User Guide 32
3 Electrical System Integration

Recommended electrical specifications for the antenna

The receiver has been designed to support a wide variety of GPS antenna elements. GNSS band coverage will be dictated by the bandwidth of the antenna chosen. In addition, the unit is capable of supporting antenna elements with a minimum LNA gain of +24.5 dB. For optimum performance, the recommended antenna electrical specifications are outlined below:
Feature Specification
Frequency 1565.5 to 1614 MHz
1217 to 1257MHz VSWR 2.0 max. Bandwidth 60 MHz Impedance50 Ohm Peak Gain 4 dBic min. Amplifier
Gain Noise
Figure Output
VSWR Filtering -30 dB (+/- 100 MHz) DC Voltage
+27to +37 dB typical
Note – Required LNA gain does not account for antenna cable insertion loss.
1.5 dB typical
1.5:1 typical
+3.3 to +5 V DC
Note – Antenna LNA bias voltage is supplied directly from pin 3 on the Multi-pin Interface
Connector J5. The antenna output is rated to 10 V and can source a maximum of 400 mA
DC Current 300 mA max.
BD910 GNSS Receiver Module User Guide 33

Mechanical Drawings

4
In this chapter:
n
BD910module mechanical drawing
n
BD910evaluation I/O board
n
BD910PCB assembly schematics
The drawings in this section show the dimensions of the receiver. Refer to these drawings if you need to build mounting brackets and housings for the receiver.
BD910 GNSS Receiver Module User Guide 34
4 Mechanical Drawings

BD910 module mechanical drawing

Note – Dimensions are shown in millimeters (mm). Dimensions shown in brackets are in inches.
BD910 GNSS Receiver Module User Guide 35
4 Mechanical Drawings

BD910 evaluation I/O board

The same evaluation board is used for the BD910 and the BD920 receiver module. Current or prospective customers may obtain schematic drawings or Gerber files of the evaluation I/O board by contacting GNSSOEMSupport@trimble.com.
GNSS Receiver module
❶
Receiver status LEDs
❷
Event Pins
❸
Serial Port 4
❹
Serial Port 3
❺
Serial Port 2
❻
Serial Port 1
❼
USB Type A (not used)
❽
USB Type B
❾
Antenna Power Select
❿

Antenna jumper setting

The development board has a unique configuration to control the voltage sent to the antenna. The board has two preset voltages that the developer can use in addition to the option of setting their own voltage to the antenna.
BD910 GNSS Receiver Module User Guide 36
4 Mechanical Drawings
The figure belowshows the pre-loaded configuration:
In this mode, the antenna voltage is 3.3V. To configure antenna voltage to 5V (the other preset voltage), connect the jumper as shown:
The final option is to manually set the antenna voltage by attaching a voltage across the two pins shown:
In this configuration, the jumper can be anywhereas long as it is not attached to the 4th row (the one marked ANTPWR). Antenna power is rated at a maximum of 5V and 400mA.
BD910 GNSS Receiver Module User Guide 37
4 Mechanical Drawings

BD910 PCB assembly schematics

PCB layout recommendations

PCB assembly recommendations

BD910 GNSS Receiver Module User Guide 38
4 Mechanical Drawings
Trimble recommends that integrators design theirPCB so that when the mounting tabs are soldered this will ground the shield of the BD910/BD920 to their PCB. However, this is not required for functional bench-level evaluation since the primary ground paths are through the 80-pin connector.
BD910 GNSS Receiver Module User Guide 39

Installation

In this chapter:
n
Unpacking and inspecting the shipment
n
Installation guidelines
n
Interface board evaluation kit
n
Routing and connecting the antenna cable
n
LED functionality and operation
5
BD910 GNSS Receiver Module User Guide 40
5 Installation

Unpacking and inspecting the shipment

Visually inspect the shipping cartons for any signs of damage or mishandling before unpacking the receiver. Immediately report any damage to the shipping carrier.

Shipment carton contents

The shipment will include one or more cartons. This depends on the number of optional accessories ordered. Open the shipping cartons and make sure that all of the components indicated on the bill of lading are present.

Reporting shipping problems

Report any problems discovered after you unpack the shipping cartons to both Trimble Customer Support and the shipping carrier.

Installation guidelines

The receiver module is shipped in an unsoldered form along with the I/O evaluation board (if ordered). The I/O evaluation board has mounting slots to accommodate the GNSS module. For more information, referto the drawings of the receiver.

Considering environmental conditions

Installthe receiver in a location situated in a dry environment. Avoid exposure to extreme environmental conditions. This includes:
l
Water or excessive moisture
l
Excessive heat greater than 85 °C (185°F)
l
Excessive cold less than –40 °C (–40 °F)
l
Corrosive fluids and gases
Avoiding these conditions improves the receiver’s performance and long-term product reliability.

Supported antennas

The receiver tracks multiple GNSS frequencies; the Trimble Zephyr™ II antenna supports these frequencies.
Other antennas may be used with the receiver. However, ensure that the antenna you choose supports the frequencies you need to track.
For the BD910 receiver, the minimum required LNAgain is 24.5dB.
BD910 GNSS Receiver Module User Guide 41
5 Installation

Mounting the antennas

Choosing the correct location for the antenna is criticalto the installation. Poor or incorrect placement of the antenna can influence accuracy and reliability and may result in damage during normal operation. Followthese guidelines to select the antenna location:
l
If the application is mobile, place the antenna on a flat surface along the centerline of the vehicle.
l
Choose an area with clear viewto the sky above metallic objects.
l
Avoid areas with high vibration, excessive heat, electrical interference, and strong magnetic fields.
l
Avoid mounting the antenna close to stays, electrical cables, metal masts, and other antennas.
l
Avoid mounting the antenna near transmitting antennas, radar arrays, or satellite communication equipment.

Sources of electrical interference

Avoid the following sources of electricaland magneticnoise:
l
gasoline engines (spark plugs)
l
television and computer monitors
l
alternators and generators
l
electric motors
l
propeller shafts
l
equipment with DC-to-AC converters
l
fluorescent lights
l
switching power supplies
BD910 GNSS Receiver Module User Guide 42
5 Installation

Interface board evaluation kit

An evaluation kit is available for testing the receiver. This includes an I/O board that gives access to the following:
l
Power input connector
l
Power ON/OFF switch
l
Four serial ports through DB9 connectors
l
Ethernet through an RJ45 connector
l
USB port through USB Type B receptaclefor device mode (the BD910does not support the A receptacle for host mode).
l
Two pairs (Event and Ground) of pins for Event 1 and 2 respectively.
l
One pair of pins (PPS and GND)for the 1 PPS Output
l
Three LEDs to indicate satellite tracking, receipt of corrections, and power.
The following figure shows a typicalI/O board setup:
❶
BD910 receiver
❷
I/O board
❸
Zephyr antenna
The computer connection provides a means to set up and configure the receiver.
BD910 GNSS Receiver Module User Guide 43
5 Installation

Routing and connecting the antenna cable

1.
After mounting the antenna, route the antenna cable from the GPS antenna to the receiver. Avoid the following hazards when routing the antenna cable:
ll
Sharp ends or kinks in the cable
l
Hot surfaces (such as exhaust manifolds or stacks)
l
Rotating or reciprocating equipment
l
Sharp or abrasive surfaces
l
Door and window jams
l
Corrosive fluids or gases
2.
After routing the cable, connect it to the receiver. Use tie-wraps to secure the cable at several points along the route. For example, to provide strain relief for the antenna cable connection use a tie-wrap to secure the cablenear the base of the antenna.
Note – When securing the cable, start at the antenna and work towards the receiver.
3. When the cable is secured, coil any slack. Secure the coil with a tie-wrap and tuck it in a safe place.
BD910 GNSS Receiver Module User Guide 44
5 Installation
BD910GNSS receiver
❶
MMCX connector
❷
GNSSantenna
❸
Note – The MMCX connector at the end of antenna cable needs a CBL ASSY TNC-MMCX connector to interface with the receiver module.
BD910 GNSS Receiver Module User Guide 45
5 Installation

LED functionality and operation

The evaluation interface board comes with three LEDs to indicate satellite tracking, RTK receptions, and power. The initialboot-up sequence for a receiver lights all the three LEDs for about three seconds followed by a brief duration where allthree LEDs are off. Thereafter, use the following table to confirm tracking of satellitesignals or for basic troubleshooting.
For single antenna configurations, the following LED patterns apply:
Power LED RTK Corrections
LED
On
Off Off The receiver is turned on, but not tracking satellites.
(continuous) On
Off Blinking at 1Hz The receiver is tracking satellites, but no incoming
(continuous) On
Blinking at 1 Hz Blinking at 1Hz The receiver is tracking satellites and receiving
(continuous) On
(continuous)
Off or blinking (receiving corrections)
On
Blinking at 1Hz Off The receiver is receiving incoming RTK corrections,
(continuous) On
Blinking at 5Hz Blinking at 1Hz The receiver is receiving Moving Base RTK
(continuous) On
On (continuous) Blinking at 1 Hz The receiver is receiving Moving Base RTK
(continuous)
On (continuous)
On
On, blinking off briefly at 1 Hz
Blinking at 1Hz
(continuous)
SV Tracking LED
Status
RTK corrections are being received.
incoming RTK corrections.
Blinking at 5 Hz for a short while
Occurs after a power boot sequence when the receiver is tracking less than 5 satellites and searching for more satellites.
but not tracking satellites.
corrections at 5 Hz.
corrections at 10 or 20 Hz (the RTK LEDturns off for 100ms if a correction is lost).
Blinking at 1 Hz The receiver is in a base station mode, tracking
satellites and transmitting RTK corrections. On (continuous)
The receiver is in Boot Monitor Mode. Use the
WinFlash utility to reload application firmware onto
the board. For more information, contact technical
support.
BD910 GNSS Receiver Module User Guide 46
Troubleshooting receiver issues
Troubleshooting receiver issues
This section describes some possible receiver issues, possible causes, and how to solve them. Please read this section before you contact Technical Support.
Issue Possible cause Solution
The receiver does not turn on.
The base station receiver is not broadcasting.
Rover receiver is not receiving radio.
The receiver is not receiving satellite signals.
Externalpoweris too low.
Port settings between reference receiver and radio are incorrect.
Faulty cable between receiver and radio.
No power to radio.
The base station receiver is not broadcasting.
Incorrect over air baud rates between reference and rover.
Incorrect port settings between roving external radio and receiver.
The GPS antenna cable is loose.
The cable is damaged.
The GPS antenna is not in clear line of sight to the sky.
Check that the input voltage is within limits.
Check the settings on the radio and the receiver.
Try a different cable. Examine the ports for missing pins. Use a multimeter to check pinouts. If the radio has its own power supply, check the charge and
connections. Examine the ports for missing pins. Use a multimeter to check pinouts. See the issue "The base station receiver is not
broadcasting" above.
Connect to the rover receiver radio, and make sure that it has the same setting as the reference receiver.
If the radio is receiving data and the receiver is not getting radio communications, check that the port settings are correct.
Make sure that the GPS antenna cable is tightly seated in the GPS antenna connection on the GPS antenna.
Check the cable for any signs of damage. A damaged cable can inhibit signal detection from the antenna at the receiver.
Make sure that the GPS antenna is located with a clear view of the sky.
Restart the receiver as a last resort (turn off and then turn it on again).
BD910 GNSS Receiver Module User Guide 47
Troubleshooting receiver issues
Issue Possible cause Solution
Communication to the receiver is lost and the LEDs are not behaving normally.
The internal firmware may be corrupt.
With the receiver in the I/O board, apply power while pressing the Boot Monitor button. Reload firmware using the WinFlash utility.
Refer to the topic "Upgrading the
receiver firmware" in the BD9xx ReceiverWebHelp.
BD910 GNSS Receiver Module User Guide 48
Glossary
Glossary
1PPS
almanac
base station
BeiDou
BINEX
broadcast server
carrier
carrier frequency
carrier phase cellular modems
Pulse-per-second. Used in hardware timing. A pulse is generated in conjunction with a time stamp. This defines the instantwhen the time stamp is applicable.
A file thatcontains orbit information on all the satellites, clock corrections, and atmospheric delay parameters. The almanac is transmitted by a GNSS satellite to a GNSS receiver, where it facilitates rapid acquisition of GNSS signals when you start collecting data, or when you have lost track of satellites and are trying to regain GNSS signals.
The orbit information is a subset of the ephemeris/ephemerides data. Also called reference station. In construction, a base station is a receiver placed at a
known point on a jobsite that tracks the same satellites as an RTK rover, and provides a real-time differential correction message stream through radio to the rover, to obtain centimeter level positions on a continuous real-time basis. A base station can also be a part of a virtual reference station network, or a location at which GNSS observations are collected over a period of time, for subsequent
postprocessing to obtain the most accurate position for the location.
The BeiDou Navigation Satellite System (also known as BDS) is a Chinese satellite navigation system.
The first BeiDou system (known as BeiDou-1), consists of four satellites and has limited coverage and applications. It has been offering navigation services mainly for customers in China and from neighboring regions since 2000.
The second generation of the system (known as BeiDou-2) consists of satellites in a combination of geostationary, inclined geosynchronous, and medium earth orbit configurations.It became operational with coverage of China in December 2011. However, the complete Interface Control Document (which specifies the satellite messages) was not released until December 2012. BeiDou-2 is a regional navigation service which offers services to customers in the Asia-Pacific region.
A third generation of the BeiDou system is planned, which will expand coverage globally.This generation is currently scheduled to be completed by 2020.
BInary EXchange format. BINEX is an operational binary format standard for GPS/GLONASS/SBAS research purposes. Itis designed to grow and allow encapsulation of all (or most) of the information currently allowed for in a range of other formats.
An Internet server thatmanages authentication and password control for a network of VRS servers, and relays VRS corrections from the VRS server thatyou select.
A radio wave having at least one characteristic (such as frequency, amplitude, or phase) thatcan be varied from a known reference value by modulation.
The frequency of the unmodulated fundamental output of a radio transmitter. The GPS L1 carrier frequency is 1575.42 MHz.
Is the cumulative phase count of the GPS or GLONASS carrier signal at a given time. A wireless adaptor thatconnects a laptop computer to a cellular phone system for
datatransfer. Cellular modems, which contain their own antennas,plug into a PC Card slot or into the USB port of the computer and are available for a variety of
BD910 GNSS Receiver Module User Guide 49
Glossary
CMR/CMR+
CMRx
covariance

datum

deep discharge
DGPS differential correction
differential GPS DOP
dual-frequency GPS
wireless data services such as GPRS. Compact Measurement Record. A real-time message format developed by Trimble
for broadcasting corrections to other Trimble receivers. CMR is a more efficient alternative to RTCM.
A real-time message format developed by Trimble for transmitting more satellite corrections resulting from more satellite signals, more constellations, and more satellites. Its compactness means more repeaters can be used on a site.
A statistical measure of the variance of two random variables thatare observed or measured in the same mean time period. This measure is equal to the product of the deviations of corresponding values of the two variables from their respective means.
Also called geodetic datum. A mathematical model designed to best fit the geoid, defined by the relationship between an ellipsoid and, a point on the topographic surface, established as the origin of the datum. World geodetic datums are typically defined by the size and shape of an ellipsoid and the relationship between the center of the ellipsoid and the center of the earth.
Because the earth is not a perfect ellipsoid, any single datum will provide a better model in some locations than in others. Therefore, various datums have been established to suit particular regions.
For example, maps in Europe are often based on the European datum of 1950 (ED-
50). Maps in the United States are often based on the North American datum of 1927 (NAD-27) or 1983 (NAD-83).
All GPS coordinates are based on the WGS-84 datum surface. Withdrawal of all electrical energy to the end-point voltage before the cell or
battery is recharged. See real-time differential GPS. Differential correction is the process of correcting GNSS data collected on a rover
with data collected simultaneously ata base station. Because the base station is on a known location, any errors in data collected at the base station can be measured, and the necessary corrections applied to the rover data.
Differential correction can be done in real-time, or after the data is collected by
postprocessing.
See real-time differential GPS. Dilution of Precision. A measure of the quality of GNSS positions,based on the
geometry of the satellites used to compute the positions. When satellites are widely spaced relative to each other, the DOP value is lower, and position precision is greater. When satellites are close together in the sky, the DOP is higher and GNSS positions may contain a greater level of error.
PDOP (Position DOP) indicates the three-dimensional geometry of the satellites.
Other DOP values include HDOP(Horizontal DOP) and VDOP (Vertical DOP), which indicate the precision of horizontal measurements (latitude and longitude) and vertical measurements respectively. PDOP is related to HDOP and VDOP as follows: PDOP² = HDOP² + VDOP².
A type of receiver that uses both L1 and L2 signals from GPS satellites. A dual-
BD910 GNSS Receiver Module User Guide 50
Glossary

EGNOS

elevation
elevation mask

ellipsoid

EHT ephemeris/ephemerides
epoch
feature
firmware GAGAN
Galileo
geoid
GHT GIOVE

GLONASS

frequency receiver can compute more precise position fixes over longer distances and under more adverse conditions because it compensates for ionospheric delays.
European Geostationary Navigation Overlay Service. A Satellite-Based Augmentation System (SBAS) that provides a free-to-air differential correction service for GNSS. EGNOS is the European equivalent of WAAS, which is available in the United States.
The vertical distance from a geoid such as EGM96 to the antenna phase center. The geoid is sometimes referred to as Mean Sea Level. In the SPS GNSS receivers, a user-defined sub gridded geoid can be loaded and used, or for a small site, an inclined vertical plane adjustment is used as an approximation to the geoid for a small site.
The angle below which the receiver will not track satellites. Normally set to 10 degrees to avoid interference problems caused by buildings and trees, atmospheric issues, and multipath errors.
An ellipsoid is the three-dimensional shape that is used as the basis for mathematically modeling the earth’s surface. The ellipsoid is defined by the lengths of the minor and major axes. The earth’s minor axis is the polar axis and the major axis is the equatorial axis.
Height above ellipsoid. A list of predicted (accurate) positions or locations of satellites as a function of time.
A set of numerical parameters that can be used to determine a satellite’s position. Available as broadcast ephemeris or as postprocessed precise ephemeris.
The measurement interval of a GNSS receiver. The epoch varies according to the measurement type: for real-time measurement it is set at one second; for postprocessed measurement it can be set to a rate of between one second and one minute. For example, if datais measured every 15 seconds, loading data using 30-second epochs means loading every alternate measurement.
A feature is a physical object or event that has a location in the real world, which you want to collect position and/or descriptive information (attributes) about. Features can be classified as surface or non-surface features, and again as points, lines/break lines, or boundaries/areas.
The program inside the receiver that controls receiver operations and hardware. GPS Aided Geo Augmented Navigation. A regional SBAS system currently in
development by the Indian government. Galileo is a GNSS system built by the European Union and the European Space
Agency. It is complimentary to GPS and GLONASS. The geoid is the equipotential surface thatwould coincide with the mean ocean
surface of the Earth. For a small site this can be approximated as an inclined plane above the Ellipsoid.
Height above geoid. Galileo In-Orbit Validation Element. The name of each satellite for the European
Space Agency to test the Galileo positioning system. Global Orbiting Navigation Satellite System. GLONASS is a Soviet space-based
navigation system comparable to the American GPS system. The operational system consists of 21 operational and 3 non-operational satellites in 3 orbit planes.
BD910 GNSS Receiver Module User Guide 51
Glossary
GNSS GPS
GSOF HDOP
height
IBSS
L1
L2
L2C L5
Location RTK
Mountpoint
Moving Base

MSAS

multipath
NMEA
Global Navigation Satellite System. Global Positioning System. GPSis a space-based satellite navigation system
consisting of multiple satellites in six orbit planes. General Serial Output Format. A Trimble proprietary message format. Horizontal Dilution of Precision. HDOP is a DOPvalue thatindicates the precision of
horizontal measurements.Other DOP values include VDOP (vertical DOP) and
PDOP (Position DOP).
Using a maximum HDOP is ideal for situations where vertical precision is not particularly important, and your position yield would be decreased by the vertical component of the PDOP (for example, if you are collecting data under canopy).
The vertical distance above the Ellipsoid. The classic Ellipsoid used in GPS is WGS-
84. Internet Base Station Service. This Trimble service makes the setup of an Internet-
capable receiver as simple as possible. The base station can be connected to the Internet (cable or wirelessly). To access the distribution server, the user enters a password into the receiver. To use the server, the user must have a Trimble Connected Community site license.
The primary L-band carrier used by GPS and GLONASS satellites to transmit satellite data.
The secondary L-band carrier used by GPS and GLONASS satellites to transmit satellite data.
A modernized code that allows significantly better ability to track the L2 frequency. The third L-band carrier used by GPS satellites to transmit satellite data. L5 will
provide a higher power level than the other carriers. As a result,acquiring and tracking weak signals will be easier.
Some applications such as vehicular-mounted site supervisor systems do not require Precision RTK accuracy. Location RTK is a mode in which, once initialized, the receiver will operate either in 10 cm horizontal and 10 cm vertical accuracy, or in 10 cm horizontal and and 2 cm vertical accuracy.
Every single NTripSource needs a unique mountpoint on an NTripCaster. Before transmitting GNSS datato the NTripCaster, the NTripServer sends an assignment of the mountpoint.
Moving Base is an RTK positioning technique in which both reference and rover receivers are mobile. Corrections are sent from a “base” receiver to a “rover” receiver and the resultant baseline (vector) has centimeter-level accuracy.
MTSAT Satellite-Based Augmentation System. A Satellite-Based Augmentation System (SBAS) that provides a free-to-air differential correction service for GNSS. MSAS is the Japanese equivalent of WAAS, which is available in the United States.
Interference, similar to ghosts on an analog television screen, that occurs when GNSS signals arrive at an antenna having traversed different paths.The signal traversing the longer path yields a larger pseudorange estimate and increases the error. Multiple paths can arise from reflections off the ground or off structures near the antenna.
National Marine Electronics Association.NMEA 0183 defines the standard for interfacing marine electronic navigational devices. This standard defines a number
BD910 GNSS Receiver Module User Guide 52
Glossary
NTrip Protocol
NTripCaster
NTripClient
NTripServer
NTripSource
OmniSTAR
Orthometric elevation

PDOP

postprocessing

QZSS
real-time differential GPS
of 'strings' referred to as NMEA strings thatcontain navigational details such as positions. Most Trimble GNSS receivers can output positions as NMEA strings.
Networked Transport of RTCM via Internet Protocol (NTrip) is an application-level protocol that supports streaming Global Navigation Satellite System (GNSS) data over the Internet. NTrip is a generic, stateless protocol based on the Hypertext Transfer Protocol (HTTP). The HTTP objects are extended to GNSS data streams.
The NTripCaster is basically an HTTP server supporting a subset of HTTP request/response messages and adjusted to low-bandwidth streaming data. The NTripCaster accepts request messages on a single port from either the NTripServer or the NTripClient. Depending on these messages, the NTripCaster decides whether there is streaming datato receive or to send.
Trimble NTripCaster integrates the NTripServer and the NTripCaster. This port is used only to accept requests from NTripClients.
An NTripClient will be accepted by and receive datafrom an NTripCaster, if the NTripClient sends the correct request message (TCP/UDP connection to the specified NTripCaster IP and listening port).
The NTripServer is used to transfer GNSS data of an NTripSource to the NTripCaster. An NTripServer in its simplest setup is a computer program running on a PC that sends correction data of an NTripSource (for example, as received through the serial communication port from a GNSS receiver) to the NTripCaster.
The NTripServer - NTripCaster communication extends HTTP by additional message formats and status codes.
The NTripSources provide continuous GNSS data (for example, RTCM-104 corrections) as streaming data. A single source represents GNSS data referring to a specific location. Source description parameters are compiled in the source-table.
The OmniSTAR HP/XP service allows the use of new generation dual-frequency receivers with the OmniSTAR service. The HP/XP service does not rely on local reference stations for its signal, but utilizes a global satellite monitoring network. Additionally,while most current dual-frequency GNSS systems are accurate to within a meter or so, OmniSTAR with XP is accurate in 3D to better than 30 cm.
The Orthometric Elevation is the height above the geoid (often termed the height above the 'Mean Sea Level').
Position Dilution of Precision. PDOP is a DOP value thatindicates the precision of three-dimensional measurements. Other DOP values include VDOP (vertical DOP) and HDOP (Horizontal Dilution of Precision).
Using a maximum PDOP value is ideal for situations where both vertical and horizontal precision are important.
Postprocessing is the processing of satellite data after it is collected, in order to eliminate error. This involves using computer software to compare data from the rover with data collected at the base station.
Quasi-Zenith Satellite System. A Japanese regional GNSS eventually consisting of three geosynchronous satellites over Japan.
Also known as real-time differential correction or DGPS. Real-time differential GPS is the process of correcting GPS data as you collect it. Corrections are calculated at a base station and then sent to the receiver through a radio link. As the rover
BD910 GNSS Receiver Module User Guide 53
Glossary

rover

Roving mode

RTCM

RTK

SBAS

sCMRx
signal-to-noise ratio
skyplot
SNR Source-table
receives the position itapplies the corrections to give you a very accurate position in the field.
Most real-time differential correction methods apply corrections to code phase positions.
While DGPS is a generic term, its common interpretation is that it entails the use of single-frequency code phase data sent from a GNSS base station to a rover GNSS receiver to provide sub-meter positionaccuracy. The rover receiver can be at a long range (greater than 100 kms (62 miles)) from the base station.
A rover is any mobile GNSS receiver that is used to collect or update datain the field, typically at an unknown location.
Roving mode applies to the use of a rover receiver to collect data, stakeout, or control earthmoving machinery in real time using RTK techniques.
Radio Technical Commission for Maritime Services. A commission established to define a differential datalink for the real-time differential correction of roving GNSS receivers. There are three versions of RTCM correction messages. All Trimble GNSS receivers use Version 2 protocol for single-frequency DGPS type corrections. Carrier phase corrections are available on Version 2, or on the newer Version 3 RTCMprotocol, which is available on certain Trimble dual-frequency receivers. The Version 3 RTCM protocol is more compact but is not aswidely supported as Version
2. real-time kinematic. A real-time differential GPS method that uses carrier
phasemeasurements for greateraccuracy.
Satellite-Based Augmentation System. SBAS is based on differential GPS, but applies to wide area (WAAS/EGNOS/MSAS) networks of reference stations. Corrections and additional information are broadcastusing geostationary satellites.
Scrambled CMRx. CMRx is a new Trimble message format that offers much higher datacompression than Trimble's CMR/CMR+ formats.
SNR. The signal strength of a satellite is a measure of the information content of the signal, relative to the signal’s noise. The typical SNR of a satellite at 30° elevation is between 47 and 50 dBHz.
The satellite skyplot confirms reception of a differentially corrected GNSS signal and displays the number of satellites tracked by the GNSS receiver, as well as their relative positions.
See signal-to-noise ratio. The NTripCaster maintains a source-table containing information on available
NTripSources, networks of NTripSources, and NTripCasters, to be sent to an NTripClient on request. Source-table records are dedicated to one of the following:
l
data STReams (record type STR)
l
CASters (record type CAS)
l
NETworks of data streams (record type NET)
All NTripClients must be able to decode record type STR. Decoding types CAS and NET is an optional feature. All data fields in the source-table records are separated using the semicolon character.
BD910 GNSS Receiver Module User Guide 54
Glossary
triple frequency GPS UTC
xFill
variance
VDOP
VRS

WAAS

WGS-84

A type of receiver that uses three carrier phase measurements (L1, L2, and L5). Universal Time Coordinated. A time standard based on local solar mean time at the
Greenwich meridian. Trimble xFill™ is a new service that extends RTK positioning for several minutes
when the RTK correction stream is temporarily unavailable. The Trimble xFill service improves field productivity by reducing downtime waiting to re-establish RTK corrections in black spots. It can even expand productivity by allowing short excursions into valleys and other locations where continuous correction messages were not previously possible. Proprietary Trimble xFill corrections are broadcast by satellite and are generally available on construction sites globally where the GNSS constellations are also visible. Itapplies to any positioning task being performed with a single-base, Trimble Internet Base Station Service (IBSS), or VRS™ RTK correction source.
A statistical measure used to describe the spread of a variable in the mean time period. This measure is equal to the square of the deviation of a corresponding measured variable from its mean. See also covariance.
Vertical Dilution of Precision. VDOP is a DOP value (dimensionless number) that indicates the quality of GNSS observations in the vertical frame.
Virtual Reference Station. A VRS system consists of GNSS hardware, software, and communication links.It uses data from a network of base stations to provide corrections to each rover that are more accurate than corrections from a single base station.
To start using VRS corrections, the rover sends its position to the VRS server. The VRS server uses the base station datato model systematic errors (such as ionospheric noise) at the rover position. Itthen sends RTCM correction messages back to the rover.
Wide Area Augmentation System. WAAS was established by the Federal Aviation Administration (FAA) for flight and approach navigation for civil aviation. WAAS improves the accuracy and availability of the basic GNSS signals over its coverage area, which includes the continental United States and outlying parts of Canada and Mexico.
The WAAS system provides correction data for visible satellites. Corrections are computed from ground station observations and then uploaded to two geostationary satellites. This data is then broadcast on the L1 frequency, and is tracked using a channel on the GNSS receiver, exactly like a GNSS satellite.
Use WAAS when other correction sources are unavailable, to obtain greater accuracy than autonomous positions.For more information on WAAS, refer to the FAA website at http://gps.faa.gov.
The EGNOS service is the European equivalent and MSAS is the Japanese equivalent of WAAS.
World Geodetic System 1984. Since January 1987, WGS-84 has superseded WGS­72 as the datum used by GPS.
The WGS-84 datum is based on the ellipsoid of the same name.
BD910 GNSS Receiver Module User Guide 55
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