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NavCom Technology, Inc.
20780 Madrona Avenue
Torrance, California 90503 USA
Tel: +1 310.381.2000
Fax: +1 310.381.2001
sales@navcomtech.com
www.navcomtech.com
P/N: 9
31000
3001
SF-2050 User Guide – Rev. G
This page is left blank intentionally
SF-2050 User Guide – Rev. G
Table of Contents
List of Figures..........................................................iv
List of Tables ............................................................v
Notices ...........................................................vi
Copyright....................................................................vi
Trademarks ................................................................vi
FCC Notice................................................................ vii
User Notice................................................................ vii
Limited Warranty .......................................................viii
StarFire™ Licensing...................................................ix
USG FAR....................................................................ix
Global Positioning System ......................................... ix
Revision History.......................................................xi
Use of this Document............................................xiii
Related Documents.......................................................xiii
StarUtil User Guide....................................................xiii
Technical Reference Manual.................................... xiv
RINEXUtil User Guide..............................................xiv
Integrators Toolkit..................................................... xiv
NavCom Release Notes........................................... xiv
Related Standards......................................................... xv
ICD-GPS-200 ............................................................xv
RTCM-SC-104........................................................... xv
CMR, CMR+.............................................................. xv
NMEA-0183............................................................... xv
Publicly-Operated SBAS Signals ..............................xv
Chapter 1 Introduction .....................................17
System Overview...........................................................17
GPS Sensor System .................................................17
Accuracy....................................................................18
Features … Applies to All Models.............................18
Output Data Rate.......................................................18
NCT Binary Proprietary Data.....................................19
NMEA-0183 Data ......................................................20
Models ...........................................................................21
SF-2050G..................................................................21
SF-2050M..................................................................21
SF-2050R..................................................................22
Antennae........................................................................22
Standard....................................................................22
i
SF-2050 User Guide – Rev. G
Airborne (option)........................................................23
L-band (option – SF-2050R only)..............................23
Controller.......................................................................24
Applications...............................................................26
Unique Features............................................................26
Chapter 2 Interfacing........................................ 29
Electrical Power.........................................................29
Communication Ports................................................32
CAN Bus/Event .........................................................35
Event .........................................................................35
1 PPS ........................................................................36
Indicator Panel...............................................................37
Chapter 3 Installation....................................... 41
Standard Antenna .....................................................41
L-Band Antenna (SF-2050R Only)............................43
GPS Sensor...............................................................44
Block Diagrams.........................................................46
Communication Port Connectivity.............................48
GPS Antenna Connector...........................................49
Chapter 4 Configuration .................................. 53
Factory Default Settings ................................................54
Message Descriptions...............................................56
3rd Party Controller Configuration Settings................58
Chapter 5 Safety Instructions.......................... 59
Transport...................................................................59
Maintenance..............................................................59
External Power Source..............................................59
Safety First ................................................................60
A GPS Module Specifications.............................61
Features ....................................................................61
Time-To-First-Fix.......................................................62
Dynamics...................................................................62
Measurement Performance.......................................63
User programmable output rates ..............................64
Data Latency .............................................................64
1PPS .........................................................................64
Connector Assignments............................................64
Input/Output Data Messages.....................................65
LED Display Functions (Default)...............................65
Satellite Based Augmentation System Signals.........66
Physical and Environmental......................................66
ii
SF-2050 User Guide – Rev. G
B Antenna Specifications ....................................67
Radiation Pattern.......................................................69
Radiation Pattern.......................................................73
C StarFire™ .......................................................... 75
Description.................................................................75
Infrastructure .............................................................76
Reliability...................................................................77
How to Access the StarFire™ Service ..........................78
D Event Input Configuration................................81
Glossary ..........................................................83
iii
SF-2050 User Guide – Rev. G
List of Figures
Figure 1: SF-2050 Supplied Equipment .................. 25
Figure 2: Universal Power Adapter.......................... 30
Figure 3: AC Power Cord ........................................ 30
Figure 4: Optional DC Power Cable........................31
Figure 5: SF-2050 Front View ................................. 33
Figure 6: NavCom Serial Cable...............................34
Figure 7: SF-2050M Only Back View ...................... 35
Figure 8: SF-2050 Indicator Panel...........................37
Figure 9: Standard GPS/L-band Antenna................ 41
Figure 10: SF-2050 Base Plate Dimensions ........... 45
Figure 11: SF-2050G/M Block Diagram .................. 46
Figure 12: Radio Port Configuration, StarUtil..........47
Figure 13: SF-2050R Block Diagram....................... 47
Figure 14: Communication Port Connections..........49
Figure 15: StarUtil NMEA Message List.................. 54
Figure 16: StarUtil Rover Navigation Setup............. 55
Figure B1: AN-2004T Antenna Dimensions ............ 68
Figure B2: AN-2004T Radiation Pattern..................69
Figure B3: L-Band Antenna Dimensions.................71
Figure B4: L-Band Mounts....................................... 72
Figure B5: AN-2001L Radiation Pattern.................. 73
Figure B6: Optional Airborne Antenna Dimensions.74
Figure C1: StarFire™ Network................................80
Figure D1: Event Cable Wiring Diagram ................. 81
Figure D2: PPS & Event Latch Configuration..........82
Figure D3: Event Latch Output Rate Configuration.82
Figure G1: DTE to DCE RS-232 Pin Assignments..86
iv
SF-2050 User Guide – Rev. G
List of Tables
Table 1: Supplied Equipment...................................25
Table 2: External Power Cable Pin-Out...................29
Table 3: Optional DC Pwr Cable Pin Assignments..31
Table 4: Serial Cable Pin-Outs ................................33
Table 5: Link LED Indication (Default).....................38
Table 6: Base Station Indication..............................38
Table 7: GPS Light Indication..................................39
Table 8: Acceptable Cable Lengths.........................50
Table 9: Factory Setup Proprietary Msg COM 2......56
Table B1: Standard Antenna....................................67
Table B2: L-band SF-2050R Antenna......................70
Table D1: Event Wiring Connections.......................81
v
SF-2050 User Guide – Rev. G
Notices
SF-2050 GPS Products User Guide
P/N 96-310002-3001
Revision G
July 2008
Serial Number:
Date Delivered:
Purchased From:
Copyright
© 2008 by NavCom Technology, Inc.
All rights reserved. No part of this work or the
computer program(s) described herein may be
reproduced, stored, or transmitted by any means,
without the expressed written consent of the copyright
holders. Translation in any language is prohibited
without the expressed written consent of the copyright
holders.
Trademarks
‘find your way’, ‘NavCom Globe’ and ‘NAVCOM
TECHNOLOGY’ logos are trademarks of NavCom
Technology, Inc. StarFire™ is a registered trademark
of Deere & Company. All other product and brand
names are trademarks or registered trademarks of
their respective holders.
vi
SF-2050 User Guide – Rev. G
FCC Notice
This device complies with Part 15 of the FCC Rules.
Operation is subject to the following two conditions:
1. This device may not cause harmful
interference, and
2. This device must accept any interference
received, including interference that may
cause undesired operation.
The GPS sensor has been tested in accordance with
FCC regulations for electromagnetic interference.
This does not guarantee non-interference with other
equipment. Additionally, the GPS sensor may be
adversely affected by nearby sources of
electromagnetic radiation.
The Global Positioning System is under the control of
the United States Air Force. Operation of the GPS
satellites may be changed at any time and without
warning.
User Notice
NavCom Technology, Inc. shall not be responsible for
any inaccuracies, errors, or omissions in information
contained herein, including, but not limited to,
information obtained from third party sources, such as
publications of other companies, the press, or
competitive data organizations.
This publication is made available on an “as is” basis
and NavCom Technology, Inc. specifically disclaims
all associated warranties, whether express or implied.
In no event will NavCom Technology, Inc. be liable for
direct, indirect, special, incidental, or consequential
damages in connection with the use of or reliance on
the material contained in this publication, even if
advised of the possibility of such damages. NavCom
Technology, Inc. reserves the right to make
vii
SF-2050 User Guide – Rev. G
improvements or changes to this publication and the
products and services herein described at any time,
without notice or obligation.
Limited Warranty
NavCom Technology, Inc., warrants that its products
will be free from defects in workmanship at the time of
delivery. Under this limited warranty, parts found to
be defective or defects in workmanship will be
repaired or replaced at the discretion of NavCom
Technology, Inc., at no cost to the Buyer, provided
that the Buyer returns the defective product to
NavCom Technology, Inc. in the original supplied
packaging and pays all transportation charges,
duties, and taxes associated with the return of the
product. Parts replaced during the warranty period
do not extend the period of the basic limited warranty.
This provision does not extend to any NavCom
Technology, Inc. products, which have been
subjected to misuse, accident or improper installation,
maintenance or application, nor does it extend to
products repaired or altered outside the NavCom
Technology, Inc. production facility unless authorized
in writing by NavCom Technology, Inc.
This provision is expressly accepted by the buyer in
lieu of any or all other agreements, statements or
representations, expressed or implied, in fact or in
law, including the implied warranties of
merchantability and fitness for a particular purpose
and of all duties or liabilities of NavCom Technology,
Inc. To the buyer arising out of the use of the goods,
and no agreement or understanding varying or
extending the same will be binding upon NavCom
Technology, Inc. unless in writing, signed by a dulyauthorized officer of NavCom Technology, Inc.
This limited warranty period is one (1) year from date
of purchase.
viii
SF-2050 User Guide – Rev. G
StarFire™ Licensing
The StarFire™ signal requires a subscription that
must be purchased in order to access the service.
Licenses are non-transferable, and are subject to the
terms of the StarFire™ Signal License agreement.
For further details on the StarFire™ Signal Network,
its capabilities, terms and conditions visit
www.navcomtech.com
sales@navcomtech.com
or send an email inquiry to
USG FAR
Technical Data Declaration (Jan 1997)
The Contractor, NavCom Technology, Inc., hereby
declares that, to the best of its knowledge and belief,
the technical data delivered herewith under
Government contract (and subcontracts, if
appropriate) are complete, accurate, and comply with
the requirements of the contract concerning such
technical data
Global Positioning System
Selective availability (S/A code) was disabled on 02
May 2000 at 04:05 UTC. The United States
government has stated that present GPS users use
the available signals at their own risk. The US
Government may at any time end or change
operation of these satellites without warning.
The U.S. Department of Commerce Limits
Requirements state that all exportable GPS products
contain performance limitations so that they cannot
be used to threaten the security of the United States.
Access to satellite measurements and navigation
results will be limited from display and recordable
output when predetermined values of velocity and
altitude are exceeded. These threshold values are far
ix
SF-2050 User Guide – Rev. G
in excess of the normal and expected operational
parameters of the SF-2050 GPS Sensor.
x
SF-2050 User Guide – Rev. G
Revision History
Rev A (Dec 2002) Initial release
Rev B (Feb 2003)
Rev C (Nov 2003)
Rev D (Mar 2005)
Rev E (Aug 2005)
(continued on next page)
Inserted missing block bracket
(open) in Table 2 Cell A2
Replaced Redondo Beach
contact information with
Torrance.
Added appendix detailing
specifications for Event input;
wiring diagram, Event HI/LO
wiring table, and message
output instructions.
Minor grammatical corrections.
Used production model photo of
SF-2050 on cover.
Added USG FAR Statement
Made changes that denote
NCT-2100 where applicable
Minor formatting changes to
wording, tables, etc.
Changed Controller & Data Logger
graphic to better depict the text.
Changed antenna output voltage to
4.6 nominal
Changed power table to reflect
NCT-2100 levels
xi
SF-2050 User Guide – Rev. G
Format change
Add content for SF-2050R
Updated Specifications
Add RF cabling requirements
Add antenna patterns
Add related standards
Add related documents
Expand product overview
Add NMEA
Add DC to DC cable
Rev F (Apr 2007)
Add RTK Link LED
Add antenna placement guidelines
Update dimensional drawings
Add block diagrams
Remove datum description from text
Add figures for port settings
Expand port configuration
Add DCE DTE definitions
Add wiring diagrams
Move TOC to front of guide
Add NavCom Release Notes to
Add RTCA/DO-229D standard
Add UltraRTK™ specs
Rev G (July 2008)
Add NMEA message GBS
ITRF2000 update to ITRF2005
Update text and graphics pertaining
Add Optional Airborne Antenna
body
descriptions
Related Documents
(WAAS, EGNOS, MSAS,
GAGAN)
(Apr 08) as reference for
StarFire™ position outputs
to StarFire™ -- new satellite
uplink sites
Dimensional Drawing
xii
SF-2050 User Guide – Rev. G
Use of this Document
This User Guide is intended to be used by someone
familiar with the concepts of GPS and satellite
surveying equipment.
Note indicates additional information
to make better use of the product.
This symbol means Reader Be
Careful. Indicates a caution, care,
and/or safety situation. The user might
do something that could result in
equipment damage or loss of data.
This symbol means Danger. You are in
a situation that could cause bodily
injury. Before you work on any
equipment, be aware of the hazards
involved with electrical and RF circuitry
and be familiar with standard practices
for preventing accidents.
Revisions to this User Guide can be obtained in a
digital format from
http://www.navcomtech.com/Support/
Related Documents
StarUtil User Guide P/N 96-310008-3001
Describes the operation and use of NavCom’s
Windows based control program (included on CD)
xiii
SF-2050 User Guide – Rev. G
Technical Reference Manual P/N 96-3120001-3001
Describes the control and output data message
formats utilized by this instrument (for customer
programming purposes; included on CD)
RINEXUtil User Guide P/N 96-310021-2101
Describes the conversion program used on NavCom
proprietary output data message formats to RINEX
ver 2.10 observation and navigation files (for
customer programming purposes; included on CD)
Integrators Toolkit P/N 97-310020-3001
Provides additional instruction and tools for
developing control programs for this instrument (not
included in the packaging material; contact
http://www.navcomtech.com/Support/
for a copy).
NavCom Release Notes
Describes software updates for NavCom products.
Current and archived Release Notes are available on
the NavCom web site:
http://www.navcomtech.com/Support/DownloadCente
r.cfm?category=releasenotes.
NavCom Customer Support provides software
updates described in the Release Notes. Submit a
request for software updates via the Request Support
web page.
xiv
SF-2050 User Guide – Rev. G
Related Standards
ICD-GPS-200
NAVSTAR GPS Space Segment / Navigation User
Interfaces Standard. ARINC Research Corporation;
2250 E. Imperial Highway; El Segundo, California
90245
RTCM-SC-104
Recommended Standards For Differential GNSS
Service. Radio Technical Commission For Maritime
Services; 1800 N. Kent St, Suite 1060; Arlington,
Virginia 22209
CMR, CMR+
Compact Measurement Record; Trimble Navigation
Limited; 935 Stewart Drive; Sunnyvale, CA 94085
NMEA-0183
National Marine Electronics Association Standard For
Interfacing Marine Electronic Devices. NMEA
National Office; 7 Riggs Avenue; Severna Park,
Maryland 21146
Publicly-Operated SBAS Signals
RTCA/DO-229D
The Radio Technical Commission for Aeronautics
(RTCA) develops consensus-based
recommendations regarding communications,
navigation, surveillance, and air traffic management
(CNS/ATM) system issues.
RTCA. 1828 L Street, NW, Suite 805, Washington,
DC 20036.
xv
SF-2050 User Guide – Rev. G
These organizations implement the RTCA/DO-229D
standard set by RTCA:
WAAS (Wide Area Augmentation System)
U.S. Department of Transportation. Federal Aviation
Administration. 800 Independence Ave, SW,
Washington, DC 20591
EGNOS (European Geostationary Navigation Overlay Service)
European Space Agency. 8, 10 rue Mario-Nikis,
F-75738 Paris Cedex 15, France.
MSAS (MTSAT Satellite-based Augmentation System)
Japan Civil Aviation Bureau. Ministry of Transport.
Kasumigaseki 2-1-3, Chiyoda-ku, Tokyo 100, Japan.
GAGAN (GPS Aided Geo Augmented Navigation)
Indian Space Research Organization. Antariksh
Bhavan, New Bel Road, Bangalore - 560 094, India.
xvi
SF-2050 User Guide – Rev. G
1
Chapter 1 ..............................Introduction
System Overview
GPS Sensor System
The SF-2050 GPS sensor
delivers unmatched
accuracy to the precise
positioning community.
This unique receiver is
designed to use
NavCom’s
network, which is a worldwide Satellite Based
Augmentation System (SBAS) for decimeter level
position accuracy (post-convergence period). The
receiver is also capable of NCT
RTCM (code and phase), and CMR/CMR+ DGPS
operating methods. The operating software is also
capable of supporting an external radio modem.
1
StarFire™
2
RTK/UltraRTK™,
The SF-2050 integrated sensor consists of:
9 24-channel, dual-frequency, precision GPS
receiver
9 2 separate SBAS channels, RTCA/DO-229D
compliant (WAAS/EGNOS/MSAS/GAGAN)
1
StarFire™ L-Band receiver
9
There are three models, the SF-2050G, SF-2050M
and the SF-2050R. Packaging and performance
standards of the models are the same; the differences
lie in the features, as described later in this chapter.
The system also includes a wide-band antenna with a
built-in LNA (SF-2050R excluded) and other
Subscription Required; 2Separate Software Option Required.
UltraRTK™ Requires NCT-2100D Engine.
1-17
SF-2050 User Guide – Rev. G
1
interconnection accessories outlined in Table 1, later
in this chapter.
Accuracy
When WAAS, EGNOS, MSAS, or GAGAN
(RTCA/DO-229D compliant) SBAS correction signals
are used, the system provides <50cm position
accuracy.
System accuracy with WAAS,
EGNOS, MSAS, or GAGAN signals is
subject to the quality and update rate
of these publicly-operated signals.
Refer to Related Standards/Publicly-
Operated SBAS Signals for contact
information regarding the
organizations that implement the
RTCA/DO-229D standard.
The system provides <10cm position accuracy (post-
2
convergence period) when StarFire™ correction
signals are used.
The system provides instant <0.5cm position
accuracy when
1
UltraRTK™ correction signals are
used (base-line, <40km, 0.5cm +1ppm). UltraRTK™
requires GPS software version 4.2 or higher.
The system provides instant <1cm position accuracy
when RTK
1
correction signals are used. (base-line,
<10km, 1cm +1ppm)
Features … Applies to All Models
Output Data Rate
Both SF-2050 models can output proprietary raw data
at programmable rates from <
rates up to 50Hz
Separate Software Option Required; 2See Glossary or Web-site
1
and Position Velocity Time (PVT)
1-18
1Hz to predetermined
SF-2050 User Guide – Rev. G
1
data at programmable rates from <1Hz to
predetermined rates up to 25Hz
1
through two 115kbps
RS-232 serial ports with less than 20ms latency.
<
10cm horizontal and <15cm vertical accuracy are
maintained as each output is independently calculated
based on an actual GPS position measurement, as
opposed to an extrapolation/interpolation between
1Hz measurements.
NCT Binary Proprietary Data
The sensor can output proprietary raw data
containing information including (but not limited to):
9 Satellite Ephemeris (0x81)
9 Satellite Almanac (0x44)
9 Raw Pseudorange Measurements (0xB0)
9 Position, Height, & Time (0xB1)
9 Velocity & Heading (0xB1)
9 Signal to Noise (0x86)
9 Channel Status (0x86)
9 Correction Data (mirror data; 0xEC)
9 Event/Marker (M model only; 0xB4)
9 Measurement Quality (0xB1 and 0xB5)
These data can be integrated in real-time positioning
applications or post-processed against any number of
software applications designed to handle NCT or
RINEX raw data. A Technical Reference Manual is
available on NavCom’s web site, which describes the
attributes of each of the input/output records (see
Related Documents in the fore-matter).
Separate Software Option Required
1-19
SF-2050 User Guide – Rev. G
NMEA-0183 Data
The SF-2050 is capable of outputting several
standard NMEA-0183 data strings (see Related
Standards in the fore-matter) and one proprietary
data sting. Each data is headed with GP. The
proprietary data sting is denoted with a $PNCT
header.
Standard:
9 ALM – GPS Almanac Data
9 GBS – GNSS Satellite Fault Detection
9 GGA – GPS Fix Data
9 GLL – Geographic Position – Lat / Lon
9 GSA – GNSS DOP & Active Satellites
9 GST – GNSS Pseudorange Error Statistics
9 GSV – GNSS Satellites In View
9 RMC – Recommended Minimum Specific GNSS
Data
9 VTG – Course Over Ground & Ground Speed
9 ZDA – Time & Date
Proprietary (header $PNCT):
9 SET – Solid Earth Tide
Described in the Technical Reference Manual (see
Related Documents in the fore-matter)
1-20
SF-2050 User Guide – Rev. G
1
Models
SF-2050G
This model is designed for:
9 Geographical Information System (GIS)
9 Aerial Surveying (VueSta r)
9 Hydrographic Surveying
9 Post-processed Dual-frequency Surveys
9 Real-time Positioning Applications
The sensor can be carried in a backpack with the
antenna either pole-mounted from the backpack or on
a survey pole.
SF-2050M
This model is ideal for vehicle mounting to suit a wide
variety of machine guidance and control applications
in:
9 Agriculture
9 Mining
9 Aerial Surveying
9 Hydrographic Surveying
It is equipped with additional features allowing
interconnectivity with a wide variety of antennas,
vehicle data busses and other instrumentation to suit
specific applications and configurations. Features that
distinguish this model include:
9 A 1PPS output port
9 A combined Event/CAN Bus interface port
1
9 A wide variety of antennas
An Event latch interface may be necessary for mechanically
devices (i.e. camera shutter)
1-21
SF-2050 User Guide – Rev. G
SF-2050R
This model is the same as the M model, except that it
is designed for vehicle mounting with separate
antennas for GPS/WAAS/EGNOS/MSAS/GAGAN
(PN: 82-001002-3002) and StarFire™ (PN: 82001003-0001). The purpose of the separate antenna
systems is to provide better low-elevation look angles
to the StarFire™ signals in high-latitude locations.
The GPS antenna port provides
4.3VDC and the StarFire™ antenna
port provides 5.0VDC. Care must be
taken to select an appropriately rated
GPS antenna if the standard NavCom
antenna is not used.
Antennae
Standard
The standard integrated
antenna (PN: 82-001002-
3002) tracks all GPS,
WAAS/EGNOS/MSAS/GAGAN and StarFire™
signals. Our compact GPS antenna has excellent
tracking performance and a stable phase center for
GPS L1 and L2. This antenna is listed in the NOAA
GPS Antenna Calibration tables, as NAVAN2004T.
The robust housing assembly features a standard
5/8” BSW thread for mounting directly to a surveyor’s
pole, tripod, or mast and is certified to 70,000 feet
(see Specifications for restrictions).
1-22
SF-2050 User Guide – Rev. G
Airborne (option)
Included with the VueStar
system.
The airborne integrated
antenna (PN: 82-001002-
3001) tracks all GPS, WAAS/EGNOS/MSAS/GAGAN
and StarFire™ signals. Our compact GPS antenna
has excellent tracking performance and a stable
phase center for GPS L1 and L2. This antenna is
listed in the NOAA GPS Antenna Calibration tables,
as NAVAN2008T. The robust housing assembly
features a flat mounting surface with four mounting
holes and a downward facing TNC connector. This
antenna is also certified to 70,000 feet (see
Specifications for restrictions).
L-band (option – SF-2050R only)
The L-band antenna (PN: 82-001003-
0001) tracks StarFire™ signals. This
antenna has excellent tracking
performance of geostationary
satellites for latitudes furthest from the
equator. The robust housing assembly
features a flat mounting surface with
two mounting holes and a 3m coaxial
cable with an SMA and a TNC
connector. A 5/8” surveyors mount is
also available. The SF-2050R uses
the SF-2050M GPS antenna to
receive the GPS and WAAS/EGNOS/
MSAS/GAGAN signals.
1-23
SF-2050 User Guide – Rev. G
Controller
The SF-2050 GPS sensor is designed for use with an
external controller solution connected via one of two
serial COM ports.
This may be accomplished using a PC, Tablet PC or
Personal Digital Assistant (PDA) and a software
program which implements the rich control language
defined for NavCom GPS products. Refer to the
user’s guide of your controller solution for further
information. NavCom lists several application
software solutions on our website:
http://www.navcomtech.com/Support/ApplicationSoftware.cfm
In addition, NavCom provides a Windows™ based
software utility, called StarUtil, with the receiver.
The StarUtil User Guide, P/N 96-310008-3001, is
available on-line at
http://www.navcomtech.com/Support/DownloadCenter.cfm?categ
ory=manuals.
1-24
SF-2050 User Guide – Rev. G
Included Items
Figure 1: SF-2050 Supplied Equipment
Table 1: Supplied Equipment
SF-2050 GPS Sensor
(SF-2050G P/N 92-310056-3001)
1
(SF-2050M P/N 92-310056-3002)
(SF-2050R P/N 92-310056-3003)
LEMO 7-Pin to DB9S Data Cable, 6 ft
2
(P/N 94-310059-3006)
Compact L1/L2 Tri-Mode GPS Antenna
3
(P/N 82-001002-3002)
GPS Antenna Cable, 12 ft
4
(P/N 94-310058-3012)
LEMO 4-Pin Universal AC/DC Power Adapter 12vdc, 2A
5
(P/N 82-020002-5001)
CD-Rom containing User Guides, brochures, software
6
utilities, and technical papers.
(P/N 96-310006-3001)
SF-2050 User’s Guide {Not Shown}
7
(P/N 96-310002-3001 Hard Copy)
Ruggedized Travel Case {Not Shown}
8
(P/N 79-100100-0002)
9 American 2-Pin AC power Cord, 10 ft {Not Shown}
1-25
SF-2050 User Guide – Rev. G
1
Applications
The SF-2050 GPS sensors meet the needs of a large
number of applications including, but not limited to:
9 Land Survey / GIS
9 Asset Location
9 Hydrographic Survey
9 Photogrammetric Survey
9 Machine Control
9 Railway, Ship and Aircraft Precise Location
NavCom lists several application software solutions
on our website:
http://www.navcomtech.com/Support/ApplicationSoft
ware.cfm
Unique Features
The SF-2050 GPS sensor has many unique features:
StarFire™
1
The ability to receive NavCom’s unique
StarFire™
correction service is fully integrated within each unit
(no additional equipment required). A single set of
corrections can be used globally enabling a user to
achieve decimeter level positioning accuracy without
the need to deploy a separate base station, thus
saving time and capital expenditure.
StarFire™ position outputs are referenced to the
ITRF2005 (Apr. 08) datum.
Positioning Flexibility
The SF-2050 is capable of using WAAS, EGNOS,
MSAS, GAGAN (RTCA/DO-229D compliant) code
corrections via two internal Satellite Based
Augmentation System (SBAS) channels. The
Subscription Required
1-26
SF-2050 User Guide – Rev. G
1
SF-2050 automatically configures to use the most
suitable correction source available and changes as
the survey dictates (this feature can be overridden).
RTK Extend™
1
RTK Extend™ enables continuous real-RTK/RTK
level positioning accuracy during radio
communication outages by utilizing NavCom’s global
StarFire™ corrections.
Traditionally, when an RTK rover loses
communication with the base station, it is unable to
continue to provide centimeter position updates for
more than a few seconds, resulting in user down-time
and reduced productivity. With RTK Extend™, a
NavCom StarFire™ receiver operating in RTK mode,
can transition to RTK Extend™ mode and maintain
centimeter level positioning during communication
loss for up to 15 minutes. RTK Extend™ allows more
efficient and uninterrupted work, enabling focused
concentration on the work rather than the tools.
Data Sampling
GPS L1 and L2 raw measurement data is up to 5Hz
in the standard configuration. An optional upgrade
allows 10, 25, and 50Hz raw measurement data via
either of the two serial ports.
The PVT (Position, Velocity, & Time) data is output at
up to 5 Hz in the standard configuration. An optional
upgrade allows 10 and 25Hz position updates for
highly dynamic applications.
GPS Performance
The SF-2050 utilizes NavCom’s NCT-2100 GPS
engine, which incorporates several patented
innovations. The engine’s industry leading receiver
sensitivity provides more than 50% signal to noise
Separate Software Option Required
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SF-2050 User Guide – Rev. G
ratio advantage over competing technologies. This
results in improved real time positioning, proven
through independent tests, when facing various
multipath environments.
Rugged Design
Units have been tested to conform to MIL-STD-810F
for low pressure, solar radiation, rain, humidity, saltfog, sand, and dust.
The rugged design of the SF-2050 system
components provides protection against the harsh
environments common to areas such as construction
sites, offshore vessels, and mines.
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SF-2050 User Guide – Rev. G
Chapter 2 .................................Interfacing
This chapter details the SF-2050 GPS sensor
connectors, LED display, appropriate sources of
electrical power, and how to interface the
communication ports.
Electrical Power
A front panel 4-pin LEMO female connector provides
electrical power to the SF-2050. Pin assignments are
given in Table 2; see Figure 4 for pin location on the
connector.
Table 2: External Power Cable Pin-Out
Pin Description
1
2
3
4
Pins 1 and 2 connect to same internal point in the
SF-2050. Likewise, pins 3 and 4 connect to the same
internal point. The supplied power cable is
constructed using 26 AWG wire.
Return
Power Input 10 to 30 VDC; 8W
Power cable longer than 5m (15ft)
must make full use of all four power
pins.
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SF-2050 User Guide – Rev. G
The SF-2050 is supplied with a universal AC/DC,
12V, 2A power adapter (P/N 82-020002-5001).
Figure 2: Universal Power Adapter
Replacement AC power cords are
available through small appliance
retailers (Radio Shack, Walmart, Best
Buy, etc.)
Figure 3: AC Power Cord
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SF-2050 User Guide – Rev. G
P/N 94-310060-3010 is an optional 10ft (3m)
unterminated power cable fitted with a LEMO plug
type (Mfr. P/N FGG.1K.304.CLAC50Z), with red strain
relief. The wiring color code and pin assignments are
labeled on the cable assembly and provided below.
Table 3: Optional DC Power Cable Pin Assignments
Color Signal Pin No
Black 1
Brown
Red 3
Orange
Figure 4: Optional DC Power Cable
The GPS sensor is protected from reverse polarity
with an inline diode. It will operate on any DC voltage
between 10 and 30 VDC, 8 watts (maximum).
Return
2
Power
4
Voltages less than 10VDC will turn the
unit off. To turn the unit on, power
must be in the 10 to 30 VDC range.
Press and hold the I/O switch in for
more than 3 seconds.
To set the receiver to power up as
soon as power is applied to the DC
Input port, refer to the StarUtil Users
Guide, Power Management or the
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SF-2050 User Guide – Rev. G
Technical Reference Manual, 0x32
Power Mode Configuration.
Voltages in excess of 30VDC will
damage the unit. The power supply
must be well conditioned with surge
protection. Vehicular electrical systems
which create voltage spikes in excess
of 30VDC will benefit from providing
power protection during vehicle engine
power-up. This can be accomplished
through a relay power-on sequence
and/or power conditioning (such as a
DC to DC converter). Do not connect
equipment directly to the vehicles
battery without in-line protection (such
as a DC to DC converter).
Communication Ports
The SF-2050 provides two 7-pin female LEMO
connector communication ports labeled COM1 and
COM2 located at the bottom front of the sensor, as
shown in Figure 5. Each conforms to the EIA RS-232
standard with data rates from 1.2 to 115.2kbps. The
connector pin-outs are described in Table 4. The
supplied interface data cable (P/N 94-310059-3006)
is constructed as described in Figure 6. The SF-2050
is configured as a DCE device. Laptop and desktop
computers are configured as DTE devices, therefore
a straight-through cable provides proper connectivity
(PC TXD pin 2 connects to SF-2050 RXD pin 2).
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SF-2050 User Guide – Rev. G
1
Table 4: Serial Cable Pin-Outs
LEMO
Pins
1
Signal Nomenclature
[DCE w/respect to DB9]
CTS - Clear To Send
5VDC to TruBlu
1
2 RD - Receive Data 2
3 TD - Transmit Data 3
4 DTR - Data Terminal Ready 4
5 RTN - Return [Ground] 5
6 DSR - Data Set Ready 6
7 RTS - Request To Send 7
DB9S
Pins
8
Figure 5: SF-2050 Front View
TruBlu – NavCom’s Bluetooth wireless accessory
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SF-2050 User Guide – Rev. G
PN: 94-310059-3006
RD (per DCE Standard Definition)
TD (per DCE Standard Definition)
DTR
GND
DSR
RTS
CTS / 5VDC
DB9S
07-00039-A
NavCom
Reciever
LEMO
1
2
3
4
5
6
7
Figure 6: NavCom Serial Cable P/N 94-310059-3006
Connect pin 5 to shield of cable at both ends.
1
2
3
4
5
6
7
8
9
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SF-2050 User Guide – Rev. G
Figure 7: SF-2050M Only Back View
CAN Bus/Event
The SF-2050M provides a balanced (differential)
2-wire CAN Bus technology interface, ISO11898 -24V
compliant. The CAN interface uses an asynchronous
transmission scheme employing serial binary
interchange widely used in the automotive industry.
The data rate is defined as 250Kbps maximum with
termination resistors at each end of the cable. This
port/connector is shared with the Event Input.
CAN Bus specifications are diverse.
Drivers for the existing hardware must
be tailored to the specific
manufacturer’s equipment being
interfaced to. For further information,
e-mail NavCom Customer Support at
customersupport@NavComtech.com
Event
The SF-2050M accepts an event input pulse to
synchronize external incidents requiring precise GPS
time tagging, such as aerial photography. For
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.
SF-2050 User Guide – Rev. G
example, the action of a camera’s aperture creates
an input pulse to the Event port. The SF-2050M
outputs position and time information relative to each
photograph taken.
Specifications:
9 50 Ohm input impedance
9 3Vdc > Input Voltage, High < 6Vdc
9 0Vdc < Input Voltage, Low < 1.2Vdc
9 Minimum pulse width, 100nsec
9 Rising or Falling edge Synchronization
Connecting the shared EVT MKR/CAN BUS port
requires a five core, 5mm diameter, cable fitted with a
LEMO plug, type FGG.0K.305.CLAC50Z, plus strain
relief, NavCom P/N 94-310062-3003.
An event latch interface unit may be
necessary if the input device pulse is
unable to drive the input.
Detailed specifications of the Event
Input, cable wiring, and configuration
may be found in Appendix D of this
User Guide.
1 PPS
A pulse is available from the SF-2050M at an output
rate of once per second. This pulse can be used for a
variety of Time/ Mark applications where relative
timing is required.
Specifications:
9 12.5ns relative accuracy
9 Better than 100ns absolute accuracy
9 50 Ohm, TTL level
9 Pulse width, default 100mS, range 10 – 999mS
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SF-2050 User Guide – Rev. G
9 Pulse delay, default 0mS, range 0 – 999mS
9 Rising or Falling Edge Synchronization
A BNC female connector provides the 1PPS output
pulse. A 3ft (0.9m) long, BNC male to BNC male
cable (P/N 94-310050-3003) is available from
NavCom.
Indicator Panel
Figure 8: SF-2050 Indicator Panel
The indicator panel provides a quick status view of
the StarFire™ signal strength, base station correction
type, GPS navigation/operating mode, and the On/Off
(I/O) switch, respectively. Each set of indicators has
three LEDs.
To power the unit on or off, depress the I/O switch for
more than 3 seconds. All LEDs illuminate for a period
of 3-5 seconds during power-up of the GPS sensor.
Link LEDs
The Link LEDs are software
configurable via the x3f proprietary
command. Only the factory default
configuration is described here.
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SF-2050 User Guide – Rev. G
Table 5: Link LED Indication (Default)
LINK Status
Command Mode
Repeating Red to Amber to Green indicates
Searching StarFire™ signal
C/No >8dB - Strong Signal Strength from
StarFire™
C/No >4dB but <8dB - Medium Signal
Strength StarFire™
C/No <4dB - Weak Signal Strength
StarFire™
Base LEDs
Table 6: Base Station Indication
BASE Status
The BASE LEDs are not utilized in
StarFire™ operating mode
The following BASE LEDs reflect the type of RTK
corrections when the SF-2050 is operated as a Base
Station
RTK/UltraRTK™ - NCT Proprietary
(1Hz blink rate)
CMR (1Hz blink rate)
RTCM 18, 19 (1Hz blink rate)
20, 21 (5Hz blink rate)
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SF-2050 User Guide – Rev. G
GPS LEDs
Table 7: GPS Light Indication
GPS Status
Power is off
Power is on, No satellites tracked
Tracking satellites, position not available yet
Non-differential positioning
Code based differential positioning
Dual frequency Phase positioning
The GPS LEDs blink at the PVT
positioning rate (1, 5, 10, or 25Hz)
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SF-2050 User Guide – Rev. G
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SF-2050 User Guide – Rev. G
Chapter 3 .................................Installation
This chapter provides guidance on hardware
installation for optimum performance.
Standard Antenna
The 5/8 inch BSW threaded antenna mount has a
depth of 16mm (0.63 inch).
It is possible to remove the 5/8 inch BSW threaded
alloy insert to reveal a secondary means of mounting
the antenna, a 1-14UNS-2B thread with a depth of
16mm (0.63 inch). This is a typical marine industry
mount for navigation antennas.
The BSW insert is secured in-place with an
adhesive, and its removal will change the
shock and vibration sustainability
characteristics of the antenna mount.
Figure 9: Standard GPS/L-band Antenna
Do not loosen or remove the eight Phillips
screws on the base of the antenna for
mounting purposes. This will VOID the
warranty and compromise the environmental
seal of the antenna, leading to internal
damage.
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SF-2050 User Guide – Rev. G
9 Antenna placement is critical to good system
performance. Avoid antenna shading by buildings,
rooftop structures, foliage, hills/mountains, etc.
9 Locate the antenna where it has a clear view of
the sky, to an elevation angle of 7º if possible.
Obstructions below 15º elevation generally are
not a problem, though this is dependent on
satellite availability for the local region.
9 Avoid placing the antenna where more than 90º
azimuth of the sky is obstructed. When more than
90º of azimuth is shaded, it is often still possible
for the reciever to navigate, however, poor
satellite geometry (due to satillte shading) will
provide poor positioning results. Even 10º of
shading can have a negative effect on
performance, though this generally is not the
case.
9 Avoid placing the antenna on or near metal or
other electrically reflective surfaces.
9 Do not paint the antenna enclosure with a
metallic-based paint.
9 Avoid placing the antenna near electrical motors
(elevator, air conditioner, compressor, etc.)
9 Do not place the antenna too close to other active
antennas. The wavelength of L2 is 0.244m and L1
is 0.19m. The minimum acceptable separation
between antennas is 1m (39 in), which provides
6dB of isolation. For 10 dB of isolation, separate
the GPS antennas by 2.5m, and for 13dB of
isolation (recommended) separate the antennas
by 5m.
9 Active antennas (those with LNA’s or amplifiers)
create an electrical field around the antenna.
These radiated emissions can interfere with other
nearby antennas. Multiple GPS antennas in close
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SF-2050 User Guide – Rev. G
proximity to each other can create multipath and
oscillations between the antennas. These add to
position error or the inability to process the
satellite signals.
9 Most antenna’s have better gain when the satellite
is high in elevation. Expect tracking performance
to fade as the satellite lowers in elevation. It is not
unusual to see 10dB difference in antenna gain
(which translates into signal strength) throughout
the entire elevation tracking path.
9 Map obstructions above the horizon using a
compass and inclinometer. Use satellite prediction
software with a recent satellite almanac to assess
the impact on satellite visibility at that location
(available on NavCom’s web site).
9 A clear line of sight between the antenna and the
local INMARSAT satellite is required to track the
StarFire™ signal. INMARSAT satellites are geosynchronized 35,768kms above the Equator,
currently at Longitudes 15.5° West, 098° West,
142° West, 025° East, 109° East, and
143.5° East. An inclination and bearing estimation
tool is available on NavCom’s website to aid in
determining potential obstructions to StarFire™
signal.
L-Band Antenna (SF-2050R Only)
The separate L-band antenna for the SF-2050R is
used in high latitude applications and most frequently
on marine vessels. This is an active antenna,
meaning it has a built-in LNA. Therefore, this antenna
should have good isolation from other near-frequency
antennae. The best practice is to follow the same
precautions as the standard GPS antenna. On marine
platforms with many antenna systems, it is better to
locate the standard GPS antenna closer to the
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SF-2050 User Guide – Rev. G
wheelhouse, but out of the radar or satcom beam
path and the L-band antenna high on the mast. For
best performance, do not allow more than 7dB of
cable loss between the antenna and the receiver.
Applications without the L-band antenna and
operating at high latitudes should mount the GPS
antenna high on the mast, with the same
considerations for beam path avoidance and cable
loss limitations.
NavCom provides a tool on our website to aid in
determining when the SF-2050R is appropriate to use
over the SF-2050M:
http://www.navcomtech.com/Support/Tools/AntennaT
ool/main.cfm
GPS Sensor
Mount the SF-2050 GPS sensor to a flat surface.
Shock isolators suitable for 1.8kg (4lbs) may be
necessary for environments with high vibration, i.e.
Earth moving equipment or aircraft installation.
The SF-2050G can be installed in a backpack for
mobile surveying applications.
Do not place the sensor be in a confined space or
where it may be exposed to excessive heat, moisture,
or humidity.
There are no user serviceable parts
inside the SF-2050 GPS sensor.
Removing the screws that secure the
front end and rear end plates will void
the equipment warranty.
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SF-2050 User Guide – Rev. G
Figure 10: SF-2050 Base Plate Dimensions
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SF-2050 User Guide – Rev. G
Block Diagrams
The SF-2050 has three user configurable physical
communications ports (two external and one internal)
and several logical communications ports. To aid in
distinguishing these ports, please refer to the block
diagrams below.
Figure 11: SF-2050G/M Block Diagram
These user configurable physical ports
are Com1, Com2, and
Radio/Diagnostic. The Com ports are
described in the next section. The
Radio/Diagnostic port connects to an
internal UHF radio in NavCom’s RTline of products and is not used, nor
should it be assigned as a logical port
in any of the SF-2050 products.
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SF-2050 User Guide – Rev. G
Figure 12: Radio Port Configuration, StarUtil
GPS Antenna
NCT-2100D IOP
Figure 13: SF-2050R Block Diagram
StarFire Antenna
4.3VDC
50mA
19.2K
115K
Com2 Com1 1PPS
115K
Event
CAN
19.2K
5VDC
50mA
LBM
SF-2050R
07-00038-A
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SF-2050 User Guide – Rev. G
Communication Port Connectivity
Connect the supplied LEMO 7-Pin connector of the
serial cable (P/N 94-310059-3006) to COM 2 (factory
default Control Port) of the SF-2050. Connect the
DB9 end to the control device.
Some devices may require an additional
adapter. The receiver is configured as a DCE
device.
COM 2 is the SF-2050 logical control port by
default. COM 1 can be configured as the
control port by using the appropriate NavCom
proprietary commands or StarUtil. However,
there are caveats to Logical / Physical port
assignments.
The Control Port is a logical input/output port
and can not share the physical port with any
other logical port. The Control Port typically
handles the most data and requires baud
rates in excess of 19.2K baud, particularly in
multi-hertz measurement and navigation
applications. Though Com 1 is physically
capable of operating at 115K baud, the
throughput from the NCT-2100D to the IOP is
limited to 19.2K baud (refer to Figure 11).
Thus, the recommendation to maintain Com 2
as the Control port for multi-hertz applications.
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In the Rover, the NMEA Port is an output
logical port and may share the data physical
port (non-Control) with RTCM, CMR, or NCT
RTK/UltraRTK™ input corrections. In the
Base Station, the NMEA port can not share
the data port with any RTCM, CMR, or NCT
RTK/UltraRTK™ output corrections.
SF-2050 User Guide – Rev. G
Refer to the Technical Reference Manual for
available port configuration settings.
Figure 14: Communication Port Connections
GPS Antenna Connector
The connector used on the SF-2050 is a TNC female,
labeled GPS on the front panel of the sensor as
shown in Figure 5.
The SF-2050M and SF-2050G GPS
connector provides 5 VDC, 50mA max
power the antenna preamplifier. The
SF-2050-R GPS connector provides
4.25 to 4.75 VDC, 50mA max power
the GPS antenna preamplifier, and the
StarFire™ connector provides 5.0
VDC, 50mA max power the StarFire™
only antenna preamplifier. Do not
disconnect the antenna when the GPS
unit is powered on.
The system is supplied with 12ft (3.6m) of RG58/U
cable (P/N 94-310058-3012). The cable is fitted with
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SF-2050 User Guide – Rev. G
a right angle male TNC connector and a straight male
TNC connector respectively.
The cable length between the antenna and SF-2050
should not exceed 7dB loss at 1.575GHz for optimum
performance, though the system may tolerate up to
10dB of cable loss with minimal performance. Lower
elevation satellite tracking suffers the most with more
than 7dB insertion loss.
Table 8: Acceptable Cable Lengths
Cable
Type
RG-58C 19.605 36.00 7.06 64.32 11.00 7.08
RG-142 16.494 43.00 7.09 54.12 13.00 7.04
RG-213 9.564 74.00 7.08 31.38 22.50 7.06
RG-223 17.224 41.00 7.06 56.51 12.50 7.06
LMR600 3.407 207.00 7.05 11.18 63.00 7.04
LMR400 5.262 133.00 7.00 17.26 41.00 7.08
LMR240 10.127 70.00 7.09 33.23 21.00 6.98
LMR195 14.902 47.00 7.00 48.89 14.00 6.85
Atten.
(dB) per
100 Ft.
Cable
Length
in Feet
Loss
in dB
Atten.
(dB)
per
100 m
Cable
Length
Meters
Loss
in dB
in
In-line amplifiers suitable for all GPS frequencies may
be used to increase the length of the antenna cable,
but care should be exercised that tracking
performance is not degraded due to multiple
connections, noise from the amplifier, and possible
ingress of moisture and dust to the in-line amplifier.
In-line amplifier or splitter devices must pass DC
power from the receiver to the antenna, or source the
appropriate voltage and current to the antenna (see
Antenna Specifications). In-line amplifiers may also
over-saturate the receiver front-end if improperly
used.
The antenna cable can degrade signal
quality if incorrectly installed, or the cable
loss exceeds NavCom specifications.
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SF-2050 User Guide – Rev. G
Take care not to kink, stretch, distort, or
damage the antenna cable. Do not place
the cable adjacent to cables carrying
electrical power or radio frequencies. In
these instances, attempt to cross cables
at 90º angles in an effort to reduce crosscoupling of RF signals.
Where the GPS antenna is exposed to
sources of electromagnetic discharge
such as lightning, install a properly
grounded in-line electrical surge
suppressor between the GPS sensor and
antenna. Install protective devices in
compliance with local regulatory codes
and practices. Protective devices must
pass DC power from the receiver to the
antenna.
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SF-2050 User Guide – Rev. G
Chapter 4 ...............................Configuration
The SF-2050 has a rich interface and detailed control
language, allowing each unit to be individually tailored
to a specific application.
There are essentially 3 methods available to
configure and control the SF-2050:
9 StarUtil – This program is a NavCom developed
utility designed to configure and view many (but
not all) of the SF-2050 functions. In addition to its
setup capabilities, StarUtil can capture and log
data, upload new software and licenses to the
three internal processors, and query and display
various receiver performance functions. Though
it is developed as an Engineering tool, it has its
own place in the commercial market as well. The
program is provided on the CD with the SF-2050.
rd
9 3
part controller – Some manufacturers have
already integrated NavCom’s control features in
their bundled hardware and software solution kits
in a variety of applications including GIS,
Machine Control, Aerial Photogrammetry, Land &
Oceanographic Survey, Agriculture, and Military
products. Information on these applications is
available from the NavCom web site and
customer service.
9 User Program – User’s may develop unique
operating programs to control the SF-2050
(potentially in conjunction with other devices or
utilities). To facilitate this effort, NavCom has two
tools additional tools available: the Integrators
Tool Kit (ITK) and the Technical Reference
Manual (TRM). Information on these tools is
available from the NavCom web site and
customer service.
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SF-2050 User Guide – Rev. G
Factory Default Settings
COM1
9 Configuration - Data port
9 Rate – 19.2Kbps
9 Output of NMEA messages GGA & VTG
scheduled @ 1Hz rate
Though the output rate defaults to
1Hz, the data output rate can be
changed to On Change. Making this
selection in the NMEA output list will
better reflect the navigation rate
selected in the Rover Setup screen.
4-54
Figure 15: StarUtil NMEA Message List
SF-2050 User Guide – Rev. G
1
Figure 16: StarUtil Rover Navigation Setup
This port is normally used to output data to other
devices or machines that can make immediate use of
the precise positioning data available from the
SF-2050. COM1 also serves as the DGPS correction
input/output port when NCT
1
RTK/UltraRTK™, CMR,
or RTCM RTK correction services are in use.
COM2
9 Configuration - Control Port
9 Rate – 19.2Kbps
This port is normally used to input and output
proprietary messages used for navigation and
receiver setup. Table 9 describes the default
Separate Software Option Required. UltraRTK™ Requires
NCT-2100D E ngine.
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SF-2050 User Guide – Rev. G
messages needed to best initiate surveying with
minimal effort.
The user has full control over the utilized message
types and their associated rates via either StarUtil or
a third party software/utility.
Table 9: Factory Setup Proprietary Messages COM 2
Msg Rate Description
44 On Change Almanac
81 On Change Ephemeris
86 On Change Channel Status
A0 On Change Alert Message
AE 600 Seconds Identification Block
B0 On Change Raw Measurement Data
B1 On Change PVT Solution
The term “On Change” indicates that
the SF-2050 will output the specified
message only when the information in
the message changes. On occasion,
there may be an epoch without a
message block output.
Message Descriptions
The following message descriptions are fully defined
in the Technical Reference Manual (see Related
Documents)
9 44 Packed Almanac:
Data corresponding to each satellite in the GPS
constellation, including: GPS Week number of
collected almanac, GPS Time of week [in
seconds] of collected almanac, almanac
reference week, almanac reference time,
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SF-2050 User Guide – Rev. G
almanac source, almanac health, pages 1-25,
and sub-frames 4 and 5.
9 81 Packed Ephemeris:
Individual satellite tracking information including:
GPS Week number of collected ephemeris, GPS
Time of week [in seconds] of collected
ephemeris, IODC, and sub-frame 1, 2, and 3
data.
9 86 Channel Status:
Receiver channel status information containing:
the GPS week, GPS Time of Week, NCT-2100
Engine status, number of satellites
viewed/tracked, PDOP, tracked satellite identity,
satellite elevation and azimuth, C/No for the L1
and L2 signals, and correction age for each
satellite.
9 A0 Alert Text Message:
Details message receipt and processing.
9 AE Identification Block:
Details the receiver software versions (NCT2100, and IOP) and digital serial numbers.
9 B0 Raw Measurement Data:
Raw Measurement Data Block containing: the
GPS Week, GPS Time of Week, Time Slew
Indicator, Status, Channel Status, CA
Pseudorange, L1 Phase, P1-CA Pseudorange,
P2-CA Pseudorange, and L2 Phase. This data
stream is repeated for each individual tracked
satellite.
9 B1 PVT (Position, Velocity, and Time):
Provides: GPS Week number, satellites used,
latitude, longitude, navigation mode, and DOP
information.
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3rd Party Controller Configuration Settings
Please refer to the third party controller solution
manual/user guide if your SF-2050 GPS sensor is
part of an integrated solution.
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SF-2050 User Guide – Rev. G
Chapter 5 .................... Safety Instructions
The SF-2050 GPS sensor is designed for precise
navigation and positioning using the Global
Positioning System. Users must be familiar with the
use of portable GPS equipment, the limitations
thereof and these safety instructions prior to use of
this equipment.
Transport
Always carry the NavCom equipment in its case. The
case must be secured during transport to minimize
shock and vibration.
Utilize all original packaging when transporting via
rail, ship, or air.
Maintenance
The NavCom equipment may be cleaned using a new
lint free cloth moistened with pure alcohol.
Connectors must be inspected, and if necessary
cleaned before use. Always use the provided
connector protective caps to minimize moisture and
dirt ingress.
Inspect cables regularly for kinks and cuts as these
may cause interference and equipment failure.
Damp equipment must be dried at a temperature less
than +40°C (104°F), but greater than 5°C (41°F) at
the earliest opportunity.
External Power Source
The SF-2050 is supplied with an external power cable
(P/N 94-310060-3010). This must be connected to
the chosen external power solution in accordance
with Chapter 2 Interfacing\Electrical Power. It is
important that the external power source allow
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SF-2050 User Guide – Rev. G
sufficient current draw for proper operation.
Insufficient supplied current will cause damage to
your external power source.
If your chosen external power source is a disposable
battery, please dispose of the battery in accordance
with your local regulations.
Safety First
The owner of this equipment must ensure that all
users are properly trained prior to using the
equipment and are aware of the potential hazards
and how to avoid them.
Other manufacturer’s equipment must be used in
accordance with the safety instructions issued by that
manufacturer. This includes other manufacturer’s
equipment that may be attached to NavCom
Technology, Inc. manufactured equipment.
Always use the equipment in accordance with local
regulatory practices for safety and health at work.
There are no user serviceable parts inside the
SF-2050 GPS sensor. Accessing the inside of the
equipment will void the equipment warranty.
Take care to ensure the SF-2050 does not come into
contact with electrical power installations, the unit is
securely fastened and there is protection against
electromagnetic discharge in accordance with local
regulations.
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A.................... GPS Module Specifications
The technical specifications of this unit are detailed
below. NavCom Technology, Inc. is constantly
improving, and updating our technology. For the
latest technical specifications for all products go to:
http://www.navcomtech.com/Support/
These GPS sensors are fitted with an internal Lithium
coin cell battery used to maintain GPS time when
power is removed from the unit. This allows faster
satellite acquisition upon unit power up. The cell has
been designed to meet over 10 years of service life
before requiring replacement at a NavCom approved
maintenance facility.
Features
9 “All-in-view” tracking with 27 channels
(12 L1 GPS + 12 L2 GPS + 2 SBAS + StarFire™)
9 Global decimeter-level accuracy using StarFire™
corrections
9 Fully automatic acquisition of satellite broadcast
corrections
9 Rugged and lightweight package for mobile
applications
9 NavCom’s ultra compact RTK format, RTCM,
CMR or CMR+
9 L1 & L2 full wavelength carrier tracking
9 C/A, P1 & P2 code tracking
9 User programmable output rates
9 Minimal data latency
9 2 separate SBAS channels, RTCA/DO-229D
compliant (WAAS/EGNOS/MSAS/GAGAN)
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SF-2050 User Guide – Rev. G
9 Superior interference suppression
9 Patented multipath rejection
9 Output of NMEA 0183 v3.1 messages
9 Self-survey mode (position averaging)
9 CAN bus interface (SF-2050M Only)
9 1PPS Output (SF-2050M Only)
9 Event Marker (SF-2050M Only)
Time-To-First-Fix
Cold Start
Satellite
Acquisition
< 60 Seconds (typical; with
Almanac)
< 5 minutes (typical; without
Almanac)
Satellite
Reacquisition
< 6 seconds outage time;
immediate reacquisition (< 1
second)
< 30 seconds software, typical;
with outage time < 65 seconds
> 65 outage time requires full
acquisition process
Dynamics
Acceleration: up to 6g
Speed: < 515 m/s*
Altitude: < 60,000 ft*
*Restricted by export laws
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SF-2050 User Guide – Rev. G
Measurement Performance
Real-time StarFire™ SBAS Accuracy
Position (H):
Position (V):
Velocity:
<10 cm
<15 cm
0.01 m/s
Real-time RTCA/DO-229D Standard SBAS Accuracy
(WAAS/EGNOS/MSAS/GAGAN)
Position (H):
Position (V):
Velocity:
<0.5 m
<0.7 m
0.01 m/s
Code Differential GPS <200km (RMS)
Position (H):
Position (V):
Velocity:
1
UltraRTK™ Positioning <40km (RMS) (0x5E msg.)
Position (H):
Position (V):
Velocity:
<12 cm +2ppm
<25 cm +2ppm
0.01 m/s
<0.5 cm +1ppm
<1.0 cm +1ppm
0.01 m/s
RTK Positioning <10km (RMS) (0x5B msg.)
Position (H):
Position (V):
Velocity:
<1 cm +1ppm
<2 cm +1ppm
0.01 m/s
RTK Extend <10km (RMS)
Position (H):
Position (V):
Velocity:
<2 cm +1ppm
<4 cm +1ppm
0.01 m/s
Pseudo-range Measurement Precision (RMS)
Raw C/A code :
Raw carrier phase
noise:
1
Requires GPS software version 4.2 or higher.
20cm @ 42 dB-Hz
L1: 0.95 mm @ 42 dB-Hz
L2: 0.85 mm @ 42 dB-Hz
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SF-2050 User Guide – Rev. G
User programmable output rates
SF-2050G
PVT 1, 2, 5Hz Standard
10 & 25Hz Optional
Raw data 1, 2, 5Hz Standard
10, 25, & 50Hz Optional
SF-2050M
PVT
Raw data
1, 2, 5, 10Hz Standard
25Hz Optional
1, 2, 5, 10, 25Hz Standard
50Hz Optional
Data Latency
PVT < 20 ms at all nav rates
Raw data < 20 ms at all rates
1PPS
Accuracy: 12.5ns (Relative; User
Configurable); (SF-2050M Only)
Connector Assignments
Data Interfaces:
2 serial ports from 1200 bps to 115.2 kbps
CAN Bus I/F SF-2050M Only
Event Marker
I/P
1PPS SF-2050M Only
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SF-2050M Only
SF-2050 User Guide – Rev. G
Input/Output Data Messages
NCT Proprietary
Data
NMEA-0183
Messages
(Output Only)
Proprietary
NMEA-0183 Type
(Output Only)
Code Corrections RTCM 1 or 9
RTK Correction
Data (I/O)
PVT ,
Raw Measurement
Satellite Messages
Nav Quality
Receiver Commands
ALM, GBS, GGA, GLL, GSA,
GST, GSV, RMC, VTG, ZDA
SET
WAAS/EGNOS/MSAS/GAGAN
StarFire™
NCT Proprietary
StarFire™ (RTG Dual)
RTCM 18,19 or 20, 21
CMR+/CMR (Msg. 0, 1, 2)
RTK data only available in SF-Series
receivers optioned for RTK operation.
See Related Standards at the front of
this manual for information on the
various data formats
LED Display Functions (Default)
Link
Base Station
GPS
A-65
StarFire™ Signal Strength
(Default; User Programmable)
N/A in Standard SF-2050
Configuration
(User Programmable)
Position Quality
SF-2050 User Guide – Rev. G
Satellite Based Augmentation System Signals
RTCA/DO-229D Standard
(WAAS/EGNOS/MSAS/GAGAN)
StarFire™
Physical and Environmental
Size (L x W x H): < 8.18” x 5.67” x 3.06”
Weight: <4 lbs (1.81 kg)
External Power:
Input Voltage:
Consumption:
Connectors:
I/O Ports:
DC Power:
RF Connector:
Antenna Power 5 VDC, 0.05mA bias for LNA
Temperature (ambient)
Operating
Storage:
Humidity: 95% non-condensing
10 VDC to 30 VDC
8 W
2 x 7 pin Lemo
4 pin Lemo
TNC
-40º C to +55º C
-40º C to +85º C
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B........................... Antenna Specifications
Table B1: Standard Antenna
Part Number 82-001002-3002
Frequency 1525-1585 MHz
GPS L1 plus INMARSAT
StarFire™
1217-1237 MHz
GPS L2
L1 Phase Centre 58.7mm
Polarization Right Hand Circular (RHCP)
Pre–Amplifier 39dB gain (+/-2dB)
Noise Figure <2.5dB
Impedance 50 Ohms
VSWR / RL
Band Rejection 20 dB @ 250MHz
RF Power Handling 1 Watt
Input Voltage 4.2 to 15.0 VDC
Power Consumption 0.3W
Cable Connector TNC Female
Operating Temp
Altitude 70,000ft; 21,336m
Finish Fluid resistant Ultem, UV
≤ 2.0:1 / 9.54 dB min.
60mA +
-55°C to +85°C
stable
10mA @ 5VDC
NavCom P/N 82-001002-3001 is an optional
aircraft mount antenna, also rated to 70,000
feet (21,336m), and is TSO-C144 certified.
Designed to DO-160D Standard
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SF-2050 User Guide – Rev. G
Figure B1: PN: 82-001002-3002 Antenna Dimensions
To achieve the greatest level of accuracy,
the absolute phase center values must be
incorporated into your processing. Phase
center information on this antenna is
found on our web site:
http://www.navcomtech.com/Support/Dow
nloadCenter.cfm?category=antenna
B-68
Radiation Pattern
24º
SF-2050 User Guide – Rev. G
6.5dB @ 90º
32º
-4dB @ 5º
0dB
07-00008-A
-4.5dB @ 5º
0dB
Figure B2: AN-2004T Radiation Pattern
Optimal antenna performance is realized at
elevations greater than 30º.
There is a 10dB variation between 0º and 90º
elevation (factor 10x); therefore, lower
elevation satellites are always more difficult to
track.
There is a 5dB variation between ~35º and 0º
elevation (factor >3x)
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Table B2: L-band SF-2050R Antenna
Part Number 82-001003-001
Frequency 1525-1585 MHz
INMARSAT StarFire™
Polarization Right Hand Circular (RHCP)
Pre–Amplifier 25dB gain min. (to coax end)
Noise Figure 1.0dB typical
Impedance 50 Ohms
Input Voltage 3.0 to 5.5 VDC
Power Consumption 0.3W typical
8.5mA +
10mA @ 3.6VDC
Cable Connector TNC Female
Cable Length 3 meters
Operating Temp
Magnetic attachment
shear strength
Direct attachment
force pull
The quadrafilar
antenna wind loading
Minimum break-over
force (foliage
brushing)
-55°C to +85°C
3Kg Typical
4Kg Typical
200Km/hr.
10Kgm
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Figure B3: PN: 82-001003-0001 Antenna Dimensions
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SF-2050 User Guide – Rev. G
Figure B4: PN: 82-001003-001 Mounts
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SF-2050 User Guide – Rev. G
Radiation Pattern
Figure B5:
Optimal antenna performance is realized at
elevations between 10º and 50º.
AN-2001L Radiation Pattern
There is an 8dB variation between 40º
and 90º elevation (factor 6.3x);
therefore, higher elevation satellites
are always more difficult to track.
There is a 3dB variation between 10º
and 0º elevation (factor >2x)
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Figure B6: PN: 82-001002-3001 Antenna Dimensions
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SF-2050 User Guide – Rev. G
C .................................................StarFire™
Description
The StarFire™ Network is a global system for the
distribution of SBAS corrections giving the user the
ability to measure their position anywhere in the world
with exceptional reliability and unprecedented
accuracy of better than 10cm (4 inches). Because the
SBAS corrections are broadcast via INMARSAT geostationary satellites, the user needs no local
reference stations or post-processing to get this
exceptional accuracy. Furthermore, the same
accuracy is available virtually any where on the
earth's surface on land or sea from 76°N to 76°S
latitude, due to the worldwide coverage of these geostationary satellites.
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SF-2050 User Guide – Rev. G
Infrastructure
The system utilizes the GPS satellite system, L-Band
communication satellites, and a worldwide network of
reference stations to deliver real-time high precision
positioning.
To provide this unique service, NavCom has built a
global network of dual-frequency reference stations,
which constantly receive signals from the GPS
satellites as they orbit the earth. Data from these
reference stations is fed to two USA processing
centers in Torrance, California and Moline, Illinois
where they are processed to generate the differential
corrections.
From the two processing centers, the correction data
is fed via redundant and independent communication
links to satellite uplink stations at Laurentides,
Canada; Perth, Australia; Burum, The Netherlands;
Santa Paula, California; Auckland, New Zealand; and
Southbury, Connecticut for rebroadcast via the geostationary satellites.
The key to the accuracy and convenience of the
StarFire™ system is the source of SBAS corrections.
GPS satellites transmit navigation data on two
L-Band frequencies. The StarFire™ reference
stations are all equipped with geodetic-quality, dualfrequency receivers. These reference receivers
decode GPS signals and send precise, high quality,
dual-frequency pseudorange and carrier phase
measurements back to the processing centers
together with the data messages, which all GPS
satellites broadcast.
At the processing centers, NavCom's proprietary
differential processing techniques used to generate
real time precise orbits and clock correction data for
each satellite in the GPS constellation. This
proprietary Wide Area DGPS (WADGPS) algorithm is
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SF-2050 User Guide – Rev. G
optimized for a dual-frequency system such as
StarFire™ in which dual-frequency ionospheric
measurements are available at both the reference
receivers and the user receivers. It is the use of dualfrequency receivers at both the reference stations
and the user equipment together with the advanced
processing algorithms, which makes the exceptional
accuracy of the StarFire™ system possible.
Creating the corrections is just the first part. From our
two processing centers, the differential corrections
are then sent to the Land Earth Station (LES) for
uplink to L-Band communications satellites. The
uplink sites for the network are equipped with
NavCom-built modulation equipment, which
interfaces to the satellite system transmitter and
uplinks the correction data stream to the satellite that
broadcasts it over the coverage area. Each L-Band
satellite covers more than a third of the earth.
Users equipped with a StarFire™ precision GPS
receiver actually have two receivers in a single
package, a GPS receiver and an L-Band
communications receiver, both designed by NavCom
for this system. The GPS receiver tracks all the
satellites in view and makes pseudorange
measurements to the GPS satellites. Simultaneously,
the L-Band receiver receives the correction
messages broadcast via the L-Band satellite. When
the corrections are applied to the GPS
measurements, a position measurement of
unprecedented real time accuracy is produced.
Reliability
The entire system meets or exceeds a target
availability of 99.99%. To achieve this, every part of
the infrastructure has a built-in back-up system.
All the reference stations are built with duplicate
receivers, processors and communication interfaces,
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SF-2050 User Guide – Rev. G
which switch automatically or in response to a remote
control signal from the processing centers. The data
links from the reference stations use the Internet as
the primary data link and are backed up by dedicated
communications lines, but in fact the network is
sufficiently dense that the reference stations
effectively act as back up for each other. If one or
several fail, the net effect on the correction accuracy
is not impaired.
There are two continuously running processing
centers, each receiving all of the reference site inputs
and each with redundant communications links to the
uplink LES. The LESs are equipped with two
complete and continuously operating sets of uplink
equipment arbitrated by an automatic fail over switch.
Finally, a comprehensive team of support engineers
maintains round the clock monitoring and control of
the system.
The network is a fully automated self-monitoring
system. To ensure overall system integrity, an
independent integrity monitor receiver, similar to a
standard StarFire™ user receiver, is installed at every
reference station to monitor service quality. Data from
these integrity monitors is sent to the two
independent processing hubs in Torrance, California
and Moline, Illinois. Through these integrity monitors
the network is continuously checked for overall SBAS
positioning accuracy, L-Band signal strength, data
integrity and other essential operational parameters.
How to Access the StarFire™ Service
StarFire™ is a subscription service. The user pays a
subscription, which licenses the use of the service for
a predetermined period of time.
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Subscriptions can be purchased for quarterly,
biannual or annual periods and are available via a
NavCom authorized representative, or by contacting
NavCom Sales Department
.
An authorized subscription will provide an encrypted
keyword, which is specific to the Serial Number of the
NavCom receiver to be authorized. This is entered
into the receiver using the provided controller
solution. Typically the initial license is preinstalled at
the factory, and subsequent licenses will be installed
by the user.
The only piece of equipment needed to use the
StarFire™ system is a StarFire™ receiver. NavCom
offers a variety of receivers configured for different
applications. Details of all the StarFire™ receivers are
available from the NavCom authorized local
representative or the NavCom website at:
www.NavComtech.com
StarFire™ receivers include a dual-frequency GPS
receiver and an L-Band receiver integrated into a
single unit to provide the exceptional precise
positioning capability of the StarFire™ Network,
anywhere, anytime.
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Figure C1: StarFire™ Network
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SF-2050 User Guide – Rev. G
D ...................... Event Input Configuration
Figure D1 details the wiring of the Event/Can cable
assembly NavCom part number P/N 94-310062-
3003.
Refer to Chapter 2, Event for detailed electrical
specifications.
Table D1 details the wiring configuration required for
Event-Hi, and Event-Lo pulse sensing.
Figure D1: Event Cable Wiring Diagram
Pin #
1 Event Lo Tie Event-Hi to Ground
2 Event Hi Tie Event-Lo to Ground
3 Ground N/A
Once the cable is wired to correspond with the event
pulse requirements, configure the receiver to output
the message containing a time mark, referenced to
the time kept within the receiver, indicating when the
event is sensed (xB4).
The Event Input can be triggered on the Rising or
Falling edge of the input pulse. Configuration is
possible thru the StarUtil program. Select Receiver >
Setup > PPS and Event Latch from the menu bar.
D-81
Signal
Name
Table D1: Event Wiring Connections
Event Sync Wiring
SF-2050 User Guide – Rev. G
The PPS and Event Latch window opens (see Figure
D2).
Figure D2: PPS & Event Latch Configuration
In StarUtil, enable the Event Latch message (0xB4) in
the NCT Binary Messages output list. Select
Receiver > Messages > NCT output from the menu
bar to open the list. Set the Message Rate for 0xB4 to
On Trigger. Right-Click in the Rate cell for message
B4. Select Other > On Trigger from the menu (see
Figure D3). Once configured, the Event Latch
Message (0xB4) is output upon recognition of an
input trigger by the receiver.
Message 0xB4 is described in the
Technical Reference Manual (see Related
Documents in the fore-matter).
Figure D3: Event Latch Output Rate Configuration
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SF-2050 User Guide – Rev. G
Glossary
.yym files see meteorological files (where yy = two
digit year data was collected).
.yyn files see navigation files (where yy = two digit
year data was collected).
.yyo files see observation files (where yy = two digit
year data was collected).
almanac files an almanac file contains orbit
information, clock corrections, and atmospheric delay
parameters for all satellites tracked. It is transmitted
to a receiver from a satellite and is used by mission
planning software.
alt see altitude.
altitude vertical distance above the ellipsoid or geoid.
It is always stored as height above ellipsoid in the
GPS receiver but can be displayed as height above
ellipsoid (HAE) or height above mean sea level
(MSL).
Antenna Phase Center (APC) The point in an
antenna where the GPS signal from the satellites is
received. The height above ground of the APC must
be measured accurately to ensure accurate GPS
readings. The APC height can be calculated by
adding the height to an easily measured point, such
as the base of the antenna mount, to the known
distance between this point and the APC.
APC see antenna phase center or phase center.
Autonomous positioning (GPS) a mode of
operation in which a GPS receiver computes position
fixes in real time from satellite data alone, without
reference to data supplied by a reference station or
orbital clock corrections. Autonomous positioning is
typically the least precise positioning procedure a
Glossary-83
SF-2050 User Guide – Rev. G
GPS receiver can perform, yielding position fixes that
are precise to 100 meters with Selective Availability
on, and 30 meters with S/A off.
azimuth the azimuth of a line is its direction as given
by the angle between the meridian and the line
measured in a clockwise direction from the north
branch of the meridian.
base station see reference station.
baud rate (bits per second) the number of bits sent
or received each second. For example, a baud rate of
9600 means there is a data flow of 9600 bits each
second. One character roughly equals 10 bits.
bits per second see baud rate.
bps see baud rate.
BSW (British Standard Whitworth) a type of coarse
screw thread. A 5/8” diameter BSW is the standard
mount for survey instruments.
C/A code see Coarse Acquisition code.
CAN BUS a balanced (differential) 2-wire interface
that uses an asynchronous transmission scheme.
Often used for communications in vehicular
applications.
channel a channel of a GPS receiver consists of the
circuitry necessary to receive the signal for a single
GPS satellite.
civilian code see Coarse Acquisition code.
Coarse Acquisition code (C/A or Civilian code)
the pseudo-random code generated by GPS
satellites. It is intended for civilian use and the
accuracy of readings using this code can be
degraded if selective availability (S/A) is introduced
by the US Department of Defense.
Glossary-84
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COM# shortened form of the word Communications.
Indicates a data communications port to/from the
GPS sensor to a controller or data collection device.
Compact Measurement Record (CMR) a standard
format for DGPS corrections used to transmit
corrections from a reference station to rover sensors.
See Related Standards in Notices.
controller a device consisting of hardware and
software used to communicate and manipulate the
I/O functions of the GPS sensor.
convergence period (StarFire™) is the time
necessary for the received StarFire™ signal
corrections to be applied and the position filtered to
optimal performance. The convergence period is
typically 30 to 45 minutes to achieve <decimeter
accuracy. This period may be overcome using the
Quick Start method.
data files files that contain Proprietary, GPS, NMEA,
RTCM, or any type of data logged from a GPS
receiver.
datum A reference datum is a known and constant
surface which can be used to describe the location of
unknown points. Geodetic datums define the size and
shape of the earth and the origin and orientation of
the coordinate systems used to map the earth.
DB9P a type of electrical connector containing 9
contacts. The P indicates a plug pin (male).
DB9S a type of electrical connector containing 9
contacts. The S indicates a slot pin (female).
DCE Data Communications Equipment. Defined pin
assignments based on the IEEE RS-232 signaling
standard. See the Figure G-1:
Glossary-85
SF-2050 User Guide – Rev. G
`
Modem
DTE
DB25RJ45 DB9DB9 DB25
6
5
4
2
3
1
8
20
1
8
2
3
3
2
4
5
7
6
6
7
4
8
5
Straight-Through Cable
DCD
RD
TD
DTR
GND
DSR
RTS
CTS
DCE
1
2
3
4
5
6
7
8
07-00041-A
8
3
2
20
7
6
4
5
Figure G1: DTE to DCE RS-232 Pin Assignments
DGPS see Differential GPS.
Differential GPS (DGPS) a positioning procedure
that uses two receivers, a rover at an unknown
location and a reference station at a known, fixed
location. The reference station computes corrections
based on the actual and observed ranges to the
satellites being tracked. The coordinates of the
unknown location can be computed with sub-meter
level precision by applying these corrections to the
satellite data received by the rover.
Dilution of Precision (DOP) a class of measures of
the magnitude of error in GPS position fixes due to
the orientation of the GPS satellites with respect to
the GPS receiver. There are several DOPs to
measure different components of the error. Note: this
is a unitless value. see also PDOP.
DOP see Dilution of Precision.
DTE Data Terminal Equipment. See DCE.
Glossary-86
SF-2050 User Guide – Rev. G
dual-frequency a type of GPS receiver that uses
both L1 and L2 signals from GPS satellites. A dualfrequency receiver can compute more precise
position fixes over longer distances and under more
adverse conditions because it compensates for
ionospheric delays. The SF-2050 is a dual frequency
receiver.
dynamic mode when a GPS receiver operates in
dynamic mode, it assumes that it is in motion and
certain algorithms for GPS position fixing are enabled
in order to calculate a tighter position fix.
EGNOS (European Geostationary Navigation
Overlay Service) a European satellite system used
to augment the two military satellite navigation
systems now operating, the US GPS and Russian
GLONASS systems.
elevation distance above or below Local Vertical
Datum.
elevation mask the lowest elevation, in degrees, at
which a receiver can track a satellite. Measured from
the horizon to zenith, 0º to 90º.
ellipsoid a mathematical figure approximating the
earth’s surface, generated by rotating an ellipse on its
minor axis. GPS positions are computed relative to
the WGS-84 ellipsoid. An ellipsoid has a smooth
surface, which does not match the earth’s geoidal
surface closely, so GPS altitude measurements can
contain a large vertical error component.
Conventionally surveyed positions usually reference a
geoid, which has an undulating surface and
approximates the earth’s surface more closely to
minimize altitude errors.
epoch literally a period of time. This period of time is
defined by the length of the said period.
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GAGAN (GPS Aided Geo Augmented Navigation)
an Indian satellite system that provides a set of
corrections for the GPS satellites, which are valid for
the Indian region. They incorporate satellite orbit and
clock corrections.
geoid the gravity-equipotential surface that best
approximates mean sea level over the entire surface
of the earth. The surface of a geoid is too irregular to
use for GPS readings, which are measured relative to
an ellipsoid. Conventionally surveyed positions
reference a geoid. More accurate GPS readings can
be obtained by calculating the distance between the
geoid and ellipsoid at each position and subtracting
this from the GPS altitude measurement.
GIS (Geographical Information Systems) a
computer system capable of assembling, storing,
manipulating, updating, analyzing and displaying
geographically referenced information, i.e. data
identified according to their locations. GIS technology
can be used for scientific investigations, resource
management, and development planning. GIS
software is used to display, edit, query and analyze
all the graphical objects and their associated
information.
Global Positioning System (GPS) geometrically,
there can only be one point in space, which is the
correct distance from each of four known points. GPS
measures the distance from a point to at least four
satellites from a constellation of 24 NAVSTAR
satellites orbiting the earth at a very high altitude.
These distances are used to calculate the point’s
position.
GMT see Greenwich Mean Time.
GPS see Global Positioning System.
GPS time a measure of time. GPS time is based on
UTC, but does not add periodic ‘leap seconds’ to
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SF-2050 User Guide – Rev. G
correct for changes in the earth’s period of rotation.
As of September 2002 GPS time is 13 seconds
ahead of UTC.
Greenwich Mean Time (GMT) the local time of the
0° meridian passing through Greenwich, England.
HAE see altitude, and ellipsoid.
IODC Issue of Data, Clock - The IODC indicates the
issue number of the data set and thereby provides
the user with a convenient means of detecting any
change in the correction parameters. The transmitted
IODC will be different from any value transmitted by
the satellite during the preceding seven days.
JPL Jet Propulsion Laboratory.
Kbps kilobits per second.
L-Band the group of radio frequencies extending
from approximately 400MHz to approximately
1600MHz. The GPS carrier frequencies L1
(1575.4MHz) and L2 (1227.6 MHz) are in the L-Band
range.
L1 carrier frequency the primary L-Band carrier
used by GPS satellites to transmit satellite data. The
frequency is 1575.42MHz. It is modulated by C/A
code, P-code, or Y-code, and a 50 bit/second
navigation message. The bandwidth of this signal is
1.023MHz.
L2 carrier frequency the secondary L-Band carrier
used by GPS satellites to transmit satellite data. The
frequency is 1227.6MHz. It is modulated by P-code,
or Y-code, and a 50 bit/second navigation message.
The bandwidth of this signal is 10.23MHz.
lat see latitude.
latitude (lat) the north/south component of the
coordinate of a point on the surface on the earth;
expressed in angular measurement from the plane of
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the equator to a line from the center of the earth to
the point of interest. Often abbreviated as Lat.
LED acronym for Light Emitting Diode.
LEMO a type of data or power connector.
LES Land Earth Station the point on the earth’s
surface where data is up linked to a satellite.
logging interval the frequency at which positions
generated by the receiver are logged to data files.
lon see longitude.
longitude (long) the east/west component of the
coordinate of a point on the surface of the earth;
expressed as an angular measurement from the
plane that passes through the earth’s axis of rotation
and the 0° meridian and the plane that passes
through the axis of rotation and the point of interest.
Often abbreviated as Long.
Mean Sea Level (MSL) a vertical surface that
represents sea level.
meridian one of the lines joining the north and south
poles at right angles to the equator, designated by
degrees of longitude, from 0° at Greenwich to 180°.
meteorological (.YYm) files one of the three file
types that make up the RINEX file format. Where YY
indicates the last two digits of the year the data was
collected. A meteorological file contains atmospheric
information.
MSAS (MTSAT Satellite-based Augmentation
System) a Japanese satellite system that provides a
set of corrections for the GPS satellites, which are
valid for the Japanese region. They incorporate
satellite orbit and clock corrections.
MSL see Mean Sea Level.
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multipath error a positioning error resulting from
interference between radio waves that has traveled
between the transmitter and the receiver by two paths
of different electrical lengths.
navigation (.YYn) files one of the three file types
that make up the RINEX file format. Where YY
indicates the last two digits of the year the data was
collected. A navigation file contains satellite position
and time information.
observation (.YYo) files one of the three file types
that make up the RINEX file format. Where YY
indicates the last two digits of the year the data was
collected. An observation file contains raw GPS
position information.
P/N Part Number.
P-code the extremely long pseudo-random code
generated by a GPS satellite. It is intended for use
only by the U.S. military, so it can be encrypted to Ycode deny unauthorized users access.
parity a method of detecting communication errors by
adding an extra parity bit to a group of bits. The parity
bit can be a 0 or 1 value so that every byte will add up
to an odd or even number (depending on whether
odd or even parity is chosen).
PDA Personal Digital Assistant.
PDOP see Position Dilution of Precision.
PDOP mask the highest PDOP value at which a
receiver computes positions.
phase center the point in an antenna where the
GPS signal from the satellites is received. The height
above ground of the phase center must be measured
accurately to ensure accurate GPS readings. The
phase center height can be calculated by adding the
height to an easily measured point, such as the base
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of the antenna mount, to the known distance between
this point and the phase center.
Position the latitude, longitude, and altitude of a
point. An estimate of error is often associated with a
position.
Position Dilution of Precision (PDOP) a measure of
the magnitude of Dilution of Position (DOP) errors in
the x, y, and z coordinates.
Post-processing a method of differential data
correction, which compares data logged from a
known reference point to data logged by a roving
receiver over the same period of time. Variations in
the position reported by the reference station can be
used to correct the positions logged by the roving
receiver. Post-processing is performed after you have
collected the data and returned to the office, rather
than in real time as you log the data, so it can use
complex, calculations to achieve greater accuracy.
Precise code see P-code.
PRN (Uppercase) typically indicates a GPS satellite
number sequence from 1 – 32.
prn (Lower Case) see Pseudorandom Noise.
Protected code see P-code.
Proprietary commands those messages sent to and
received from GPS equipment produced by NavCom
Technology, Inc. own copyrighted binary language.
pseudo-random noise (prn) a sequence of data that
appears to be randomly distributed but can be exactly
reproduced. Each GPS satellite transmits a unique
PRN in its signals. GPS receivers use PRNs to
identify and lock onto satellites and to compute their
pseudoranges.
Pseudorange the apparent distance from the
reference station’s antenna to a satellite, calculated
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by multiplying the time the signal takes to reach the
antenna by the speed of light (radio waves travel at
the speed of light). The actual distance, or range, is
not exactly the same because various factors cause
errors in the measurement.
PVT GPS information depicting Position, Velocity,
Time in the NCT proprietary message format.
Quick Start (StarFire™) a startup mode that allows
instant <decimeter accuracy with received StarFire™
signals, allowing the convergence period to be
waived. The Quick Start (user input) position should
have an accuracy of better <decimeter to achieve
maximum results. Any error in the user input position
will bias the StarFire™ position error accordingly, until
convergence can correct the bias. In this scenario,
convergence may take longer than the typical startup
convergence period.
Radio Technical Commission for Maritime
Services see RTCM.
range the distance between a satellite and a GPS
receiver’s antenna. The range is approximately equal
to the pseudorange. However, errors can be
introduced by atmospheric conditions which slow
down the radio waves, clock errors, irregularities in
the satellite’s orbit, and other factors. A GPS
receiver’s location can be determined if you know the
ranges from the receiver to at least four GPS
satellites. Geometrically, there can only be one point
in space, which is the correct distance from each of
four known points.
RCP a NavCom Technology, Inc. proprietary
processing technique in which carrier phase
measurements, free of Ionospheric and Troposphere
effects are used for navigation.
Real-Time Kinematic (RTK) a GPS system that
yields very accurate 3D position fixes immediately in
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real-time. The base station transmits its GPS position
to roving receivers as the receiver generates them,
and the roving receivers use the base station
readings to differentially correct their own positions.
Accuracies of a few centimeters in all three
dimensions are possible. RTK requires dual
frequency GPS receivers and high speed radio
modems.
reference station a reference station collects GPS
data for a fixed, known location. Some of the errors in
the GPS positions for this location can be applied to
positions recorded at the same time by roving
receivers which are relatively close to the reference
station. A reference station is used to improve the
quality and accuracy of GPS data collected by roving
receivers.
RHCP Right Hand Circular Polarization used to
discriminate satellite signals. GPS signals are RHCP.
RINEX (Receiver Independent Exchange) is a file
set of standard definitions and formats designed to be
receiver or software manufacturer independent and to
promote the free exchange of GPS data. The RINEX
file format consists of separate files, the three most
commonly used are:
the observation (.YYo) file,
the navigation (.YYn) file,
meteorological (.YYm) files; where YY indicates
the last two digits of the year the data was
collected.
rover any mobile GPS receiver and field computer
collecting data in the field. A roving receiver’s position
can be differentially corrected relative to a stationary
reference GPS receiver or by using GPS orbit and
clock corrections from a SBAS such as StarFire™.
roving receiver see rover.
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RTCM (Radio Technical Commission for Maritime
Services) a standard format for Differential GPS
corrections used to transmit corrections from a base
station to rovers. RTCM allows both real-time
kinematic (RTK) data collection and post-processed
differential data collection. RTCM SC-104 (RTCM
Special Committee 104) is the most commonly used
version of RTCM message.
RTK see Real-time kinematic.
RTG Real Time GIPSY, a processing technique
developed by NASA’s Jet Propulsion Laboratory to
provide a single set of real time global corrections for
the GPS satellites.
S/A see Selective Availability.
SBAS (Satellite Based Augmentation System) this
is a more general term, which encompasses WAAS,
StarFire™ and EGNOS type corrections.
Selective Availability (S/A) is the deliberate
degradation of the GPS signal by encrypting the Pcode and dithering the satellite clock. When the US
Department of Defense uses S/A, the signal contains
errors, which can cause positions to be inaccurate by
as much as 100 meters.
Signal-to-Noise Ratio (SNR) is a measure of a
satellite’s signal strength.
single-frequency is a type of receiver that only uses
the L1 GPS signal. There is no compensation for
ionospheric effects.
SNR see signal-to-noise Ratio.
StarFire™ a set of real-time global orbit and clock
corrections for GPS satellites. StarFire™ equipped
receivers are capable of real-time decimeter
positioning
(see Appendix C).
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Spread Spectrum Radio (SSR) a radio that uses
wide band, noise like (pseudo-noise) signals that are
hard to detect, intercept, jam, or demodulate making
any data transmitted secure. Because spread
spectrum signals are so wide, they can be transmitted
at much lower spectral power density (Watts per
Hertz), than narrow band signals.
SV (Space Vehicle) a GPS satellite.
Universal Time Coordinated (UTC) a time standard
maintained by the US Naval Observatory, based on
local solar mean time at the Greenwich meridian.
GPS time is based on UTC.
UTC see Universal Time Coordinated.
WAAS (Wide Area Augmentation System) a US
satellite system that provides a set of corrections for
the GPS satellites, which are valid for the North
American region. They incorporate satellite orbit and
clock corrections.
WADGPS (Wide Area Differential GPS) a set of
corrections for the GPS satellites, which are valid for
a wide geographic area.
WGS-84 (World Geodetic System 1984) the current
standard datum for global positioning and surveying.
The WGS-84 is based on the GRS-80 ellipsoid.
Y-code the name given to encrypted P-code when
the U.S. Department of Defense uses selective
availability.
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