NavCom SF-2040 User Manual Rev.F

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NavCom Technology, Inc.

20780 Madrona Avenue
Torrance, California 90503 USA

Tel: [phone]
Fax: [phone]

[e-mail]
www.navcomtech.com

P/N: 9

31000

3001

SF-2040 User Guide – Rev. F

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SF-2040 User Guide – Rev. F

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.............................................xii

Related Documents....................................................... xii

StarUtil User Guide.................................................... xii

Technical Reference Manual.....................................xiii

RINEXUtil User Guide...............................................xiii

Integrators Toolkit......................................................xiii

NavCom Release Notes............................................xiii

Related Standards........................................................ xiv

ICD-GPS-200 ........................................................... xiv

RTCM-SC-104.......................................................... xiv

CMR, CMR+.............................................................xiv

NMEA-0183.............................................................. xiv

Publicly-Operated SBAS Signals ............................. xiv

Chapter 1 Introduction .....................................17

System Overview...........................................................17

GPS Sensor System .................................................17

Accuracy....................................................................18

Features ....................................................................18

Output Data Rate.......................................................18

NCT Binary Proprietary Data.....................................19

NMEA-0183 Data ......................................................19

Antenna..........................................................................21

Controller .......................................................................21

Applications...............................................................23

Unique Features............................................................23

i

SF-2040 User Guide – Rev. F

Chapter 2 Interfacing........................................ 27

Electrical Power.........................................................27

Communication Ports................................................29

Indicator Panel...............................................................32

Chapter 3 Installation....................................... 37

Battery Charging............................................................37

Battery Charger LEDs...............................................37

Battery Charging .......................................................38

Battery Installation.....................................................39

Battery Removal........................................................39

Battery Testing ..........................................................39

GPS Sensor...................................................................40

Block Diagram...........................................................43

Communication Port Connectivity.............................44

Chapter 4 Configuration .................................. 47

Factory Default Settings ................................................48

Message Descriptions...............................................50

3rd Party Controller Configuration Settings................51

Chapter 5 Safety Instructions.......................... 53

Transport...................................................................53

Maintenance..............................................................53

External Power Source..............................................53

Battery Packs ............................................................54

Safety First ................................................................58

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

Connector Assignments............................................64

Input/Output Data Messages.....................................65

LED Display Functions (Default)...............................65

Satellite Based Augmentation System Signals.........66

Physical and Environmental......................................66

Battery Packs ............................................................67

Battery Charger Kit....................................................67

B Antenna Specifications.................................... 69

Radiation Pattern.......................................................70

ii

SF-2040 User Guide – Rev. F

C StarFire™ .......................................................... 71

Description.................................................................71

Infrastructure .............................................................72

Reliability...................................................................73

How to Access the StarFire™ Service ..........................74

Glossary ..........................................................77

iii

SF-2040 User Guide – Rev. F

List of Figures

Figure 1: SF-2040 Supplied Equipment .................. 22

Figure 2: Optional DC Power Cable........................28

Figure 3: SF-2040 Viewed From Bottom................. 30

Figure 4: NavCom Serial Cable...............................31

Figure 5: SF-2040 Indicator Panel...........................32

Figure 6: Battery Locking Clips................................39

Figure 7: SF-2040 Dimensions................................41

Figure 8: SF-2040 Block Diagram...........................44

Figure 9: Communication Port Connections............45

Figure 10: StarUtil NMEA Message List.................. 48

Figure 11: StarUtil Rover Navigation Setup............. 49

Figure 12: NAVSF2040G Radiation Pattern............70

Figure 13: StarFire™ Network.................................76

Figure 14: DTE to DCE RS-232 Pin Assignments... 80

iv

SF-2040 User Guide – Rev. F

List of Tables

Table 1: Supplied Equipment...................................22

Table 2: External Power Cable Pin-Out...................27

Table 3: Optional DC Cable Pin Assignments.........28

Table 4: Serial Cable Pin-Outs ................................30

Table 5: Battery Status Indication............................33

Table 6: Link LED Indication (Default).....................34

Table 7: Base Station Indication..............................34

Table 8: GPS Light Indication..................................35

Table 9: Battery Charger LEDs................................37

Table 10: Factory Setup Proprietary Msgs COM 2..50

Table 11: SF-2040 Integrated Antenna....................69

v

SF-2040 User Guide – Rev. F

Notices

SF-2040 GPS Products User Guide
P/N 96-310003-3001
Revision F
March 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-2040 User Guide – Rev. F

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-2040 User Guide – Rev. F

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-2040 User Guide – Rev. F

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
[e-mail]

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-2040 User Guide – Rev. F

in excess of the normal and expected operational
parameters of the SF-2040 GPS Sensor.

x

Revision History

Rev F (Mar 2008)

SF-2040 User Guide – Rev. F

Format change
Added Revision History
In supplied equipment table,

added P/N for battery charger
kit, updated P/N’s for
batteries and travel case

Revised supplied equipment

photo to show coiled instead
of straight serial cable

Replaced old art work of

SF-2040 dimensions with

new art work
Added SF-2040 block diagram
Added specs for battery packs

and battery charger kit
Added specs for antenna
Updated text and graphics

pertaining to StarFire™ -- new

satellite longitudes and uplink

sites

xi

SF-2040 User Guide – Rev. F

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)

xii

SF-2040 User Guide – Rev. F

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

support.navcomtech.com

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/DownloadCenter.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.

xiii

SF-2040 User Guide – Rev. F

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.

xiv

SF-2040 User Guide – Rev. F

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, F­75738 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.

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SF-2040 User Guide – Rev. F

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SF-2040 User Guide – Rev. F

1

Chapter 1 ..............................Introduction

System Overview

GPS Sensor System

The SF-2040 GPS sensor
delivers unmatched accuracy
to the precise positioning community. This unique
receiver is designed to use NavCom’s StarFire™
network, which is a worldwide Satellite Based
Augmentation System (SBAS) for decimeter level
position accuracy (post-convergence period). The
receiver is also capable of RTK

2

, RTCM (code and
phase), and CMR/CMR+ DGPS operating methods.
The operating software is also capable of supporting
an external radio modem.

The SF-2040 integrated sensor consists of:

1

9 All-in-one housing incorporates compact GPS

antenna

9 24-channel, dual-frequency, precision GPS

receiver

9 2 separate SBAS channels, RTCA/DO-229D

compliant (WAAS/EGNOS/MSAS/GAGAN)

1

9 StarFire™ L-Band receiver
Refer to Table 1, later in this chapter, for the

complete list of supplied equipment.

Subscription Required; 2Separate Software Option Required

1-17

SF-2040 User Guide – Rev. F

1

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 publicly­operated 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 (post­convergence

2

period) when StarFire™ correction

signals are used.
The system provides instant <0.5cm position

accuracy when Ultra-RTK1 correction signals are
used (base-line, <40km, 0.5cm +1ppm). Ultra-RTK
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
Output Data Rate

The SF-2040 can output proprietary raw data at
programmable rates from <1Hz to predetermined
rates up to 50Hz
(PVT) data at programmable rates from <1Hz to
predetermined rates up to 25Hz
RS-232 serial ports with less than 20ms latency.
<

10cm horizontal and <15cm vertical StarFire™

1

and Position, Velocity, and Time

1

through two 115kbps

Separate Software Option Required; 2See Glossary or Web-site

1-18

SF-2040 User Guide – Rev. F

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 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).

NMEA-0183 Data

The SF-2040 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

1-19

SF-2040 User Guide – Rev. F

proprietary data sting is denoted with a $PNCT
header.

Standard:

9 ALM – GPS Almanac Data
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-2040 User Guide – Rev. F

Antenna

The SF-2040 all-in-one housing incorporates our
compact GPS antenna with excellent tracking
performance and a stable phase center for GPS L1
and L2. The integrated antenna tracks all GPS,
WAAS/EGNOS/MSAS/GAGAN and StarFire™
signals. This antenna is listed in the NGS NOAA GPS
Antenna Calibration tables, as NAVSF2040G. 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).

 Although rated to 70K feet, this antenna is not

designed for aircraft installations. Contact

[e-mail]

Controller

for aircraft solutions.

The SF-2040 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.

1-21

SF-2040 User Guide – Rev. F

Included Items

Figure 1: SF-2040 Supplied Equipment

Table 1: Supplied Equipment

SF-2040G GPS Pole Mount Sensor

1

(P/N 92-310055-3001)
LEMO 7-Pin to DB9S Data Cable, Coiled 6 ft

2

(P/N 94-310090-3003)
Battery Charger Kit

(P/N 92-310092-3001)
Kit Includes:

3

4-Bay Battery Charger w/ Cable (P/N 92-310046-3001)

4

Charger Power Supply (P/N 82-02003-5001)

Two Lithium-Ion Battery Packs, 10.8 VDC, 4.4 Ah

5

(P/N 59-020102-3001 each)
CD-Rom containing User Guides, brochures, software

6

utilities, and technical papers
(P/N 96-310006-3001)

SF-2040 User’s Guide {Not Shown}

7

(P/N 96-310003-3001 Hard Copy)
Ruggedized Travel Case {Not Shown}

8

(P/N 79-100100-0001)

1-22

SF-2040 User Guide – Rev. F

1

Applications

The SF-2040 GPS sensor meets the needs of a large
number of applications including, but not limited to:

9 Land Survey
9 GIS Field Data Collection

NavCom lists several application software solutions
on our website:

http://www.navcomtech.com/Support/ApplicationSoft
ware.cfm

Unique Features

The SF-2040 GPS sensor has many unique features:

 StarFire™

1

The ability to receive NavCom’s unique
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™

StarFire™ position outputs are referenced to the
ITRF2000 datum.

 Positioning Flexibility

The SF-2040 is capable of using WAAS, EGNOS,
MSAS, GAGAN (RTCA/DO-229D compliant) code
corrections via two internal Satellite Based
Augmentation System (SBAS) channels. The
SF-2040 automatically configures to use the most
suitable correction source available and changes as
the survey dictates (this feature can be overridden).

Subscription Required

1-23

SF-2040 User Guide – Rev. F

1

 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 output up
to 5Hz on either data port in the standard
configuration. An optional upgrade allows 10, 25, and
50Hz raw measurement data via one 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-2040 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
ratio advantage over competing technologies. This
results in improved real time positioning, proven
through independent tests, when facing various

Separate Software Option Required

1-24

SF-2040 User Guide – Rev. F

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-2040 system
components provides protection against the harsh
environments common to areas such as construction
sites.

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SF-2040 User Guide – Rev. F

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SF-2040 User Guide – Rev. F

Chapter 2 .................................Interfacing

This chapter details the SF-2040 GPS sensor
connectors, LED display, appropriate sources of
electrical power, and how to interface the
communication ports.

Electrical Power

A 4-pin LEMO female connector provides electrical
power to the SF-2040. It is located below the indicator
panel labeled DC PWR. Pin assignments are given in
Table 2; see Figure 2 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 the same internal point in the
SF-2040. Likewise, pins 3 and 4 connect to the same
internal point.

Return

Power Input 10 to 30 VDC; 8W

 Power cable longer than 5m (15ft) must make

full use of all four power pins.

P/N 82-020002-5001 is an optional universal AC/DC
12V, 2A power adapter.

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 in
Table 3 below.

2-27

SF-2040 User Guide – Rev. F

Table 3: Optional DC Power Cable Pin Assignments

Color Signal Pin No

Black 1

Brown

Red 3

Orange

Figure 2: Optional DC Power Cable

The GPS sensor is protected from reverse polarity
with an in-line diode. It operates on any DC voltage
between 10 and 30 VDC, 8 watts (maximum).

Return

2

Power

4

 Voltages less than 10VDC 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
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

2-28

SF-2040 User Guide – Rev. F

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).

Two supplied removable Lithium-Ion battery packs
(P/N 59-020102-3001) provide secondary power
when the primary external voltage is not available
(see Figure 3). External power has precedence over
the batteries, but does not charge the batteries. Each
of the two battery packs is designed to last >5 hours
on a single charge (conditions vary with use). The
smart battery interface allows the batteries to be hot­swapped on the fly.

When battery 1 voltage level is 7.5VDC to 8.2VDC,
the sensor automatically switches to battery 2 to
provide continuous power. For detailed information on
the battery packs, refer to:

9 Table 5: Battery Status Indication
9 Chapter 3 Installation\Battery Charging
9 Chapter 5 Safety Instructions\Battery Packs

Communication Ports

The SF-2040 provides two 7-pin female LEMO
connector communication ports labeled COM1 and
COM2 located below the indicator panel, as shown in
Figure 3. 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 94-310090-3003) is
constructed as described in Figure 4. The SF-2040 is

2-29

SF-2040 User Guide – Rev. F

1

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-2040 RXD pin 2).

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 3: SF-2040 Viewed From Bottom

TruBlu – NavCom’s Bluetooth wireless accessory

2-30

SF-2040 User Guide – Rev. F

Figure 4: NavCom Serial Cable P/N 94-310090-3003

Connect pin 5 to shield of cable at both ends.

2-31

SF-2040 User Guide – Rev. F

Indicator Panel

Figure 5: SF-2040 Indicator Panel

The indicator panel provides a quick status view of
the battery levels, 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.

 Battery LEDs

 The battery LEDs are software configurable

via the appropriate NavCom proprietary
command. Table 5 describes the factory
default LED states.

 Batteries are not charged in the unit. If

external power is applied, the battery LEDs
indicate the status of the batteries, not the
external power source.

 Depress the button on the indicator

panel to check the status of the battery
charge (see Table 5).

2-32

Table 5: Battery Status Indication

Battery Status

Battery Not Installed, or
Installed Battery Is Drained

Greater Than 80% Charge

SF-2040 User Guide – Rev. F

In Use LED(s) Blink Rate at 5Hz

Not In Use LED(s) Blink Rate at 1Hz

 Link LEDs

60% - 80% Charge
40% - 60% Charge
20% - 40% Charge

Less Than 20% Charge

(Solid; No Blink Rate)

 The Link LEDs are software configurable

via the x3f proprietary command. Only
the factory default configuration is
described here.

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SF-2040 User Guide – Rev. F

Table 6: 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

 The BASE LEDs reflect the type of RTK

corrections when the SF-2040 is operated
as a Base Station.

Table 7: Base Station Indication

BASE Status Blink Rate

2-34

The BASE LEDs are not
utilized in StarFire™
operating mode

RTK - NCT Proprietary

CMR

RTCM

N/A

1Hz
1Hz

18, 19=1Hz
20, 21=5Hz

SF-2040 User Guide – Rev. F

 GPS LEDs

Table 8: 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-2040 User Guide – Rev. F

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SF-2040 User Guide – Rev. F

Chapter 3 .................................Installation

This chapter provides guidance on hardware
installation for optimum performance.

Battery Charging

The SF-2040 GPS sensor is supplied with two
lithium-ion battery packs. The battery charger has
four independent charging bays for simultaneous
charging.

Charge the battery packs only with the

supplied battery charger (P/N 92­310046-3001) and supplied charger
power supply (P/N 82-02003-5001);
otherwise, damage to the battery
packs could occur.

 Refer to Chapter 5 Safety Instructions

for instructions regarding battery use,
storage, and disposal.

Battery Charger LEDs

Table 9: Battery Charger LEDs

LED Status

Power

Battery Bays

3-37

Power On

Charging
Charging Complete

SF-2040 User Guide – Rev. F

Battery Charging

 The SF-2040 battery packs are

shipped in a partially charged state.
Complete one full charge cycle (8-10

hours) before battery use.
Charge the batteries:

9 Connect the power cable to the AC to DC power

supply.

9 Connect the power supply jack to the battery

charger assembly.

9 Plug the power cable into an AC receptacle. The

green power LED illuminates.

9 Insert battery packs into the charger. The LED

status is shown in Table 9.

9 Charge battery packs until the green LED below

each bay illuminates.

Do not short circuit battery contacts.

Do not store battery packs above

60 deg C (140 deg F) or below

-20 deg C (-4 deg F). Do not

disassemble battery packs. Do not

expose to fire (explosive hazard).

If the battery packs are left charging

for longer than 5 days, the charging

indicator LEDs will shut off. If this

occurs, place the battery packs in the

SF-2040 GPS sensor and power on

for 10-15 minutes in order to slightly

discharge the batteries.

Remove the battery packs from the

SF-2040 GPS if the sensor will not be

used for over 1 week.

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SF-2040 User Guide – Rev. F

Battery Installation

The battery packs are keyed to prevent improper
installation. There are two locking clips on either side
of the battery end (see Figure 6).

Figure 6: Battery Locking Clips

The bottom of the sensor has two battery chambers.
Install each battery pack by sliding it into a chamber.
Align the channel on the chamber to match the
battery notch. Press the end firmly until the locking
clips click. Verify both locking clips are locked in
place.

If both locking clips are not locked in

place, a battery pack could
inadvertently drop to the ground.

Battery Removal

Using the thumb and the middle finger, depress the
two locking clips firmly. The battery pack should pop
out enough to be pulled free of the chamber.

Battery Testing

Depress the button on the indicator panel to
check the status of the battery charge. Refer to
Table 5 for battery status LED indications.

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SF-2040 User Guide – Rev. F

GPS Sensor

The SF-2040 housing has a female 5/8 inch BSW
threaded mount with a depth of 16mm (0.63 inch).
Mount the SF-2040 to a surveyor’s pole, tripod, mast,
or any apparatus that accepts the thread size.

Store the sensor in the ruggedized storage case. Do
not place the sensor in a space where it may be
exposed to excessive heat, moisture, or humidity.

There are no user serviceable parts

inside the SF-2040 GPS sensor.

Opening the unit compromises the

environmental seal and voids the

equipment warranty.

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SF-2040 User Guide – Rev. F

Figure 7: SF-2040 Dimensions

3-41

SF-2040 User Guide – Rev. F

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 receiver to navigate, however, poor
satellite geometry (due to satellite 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 10dB 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-2040 User Guide – Rev. F

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° West. An inclination and bearing
estimation tool is available on NavCom’s website
to aid in determining potential obstructions to
StarFire™ signal.

Block Diagram

The SF-2040 has two user configurable physical
communications ports and several internal logical
communications ports. The Com ports are described
in the next section. To aid in distinguishing these
ports, please refer to the block diagram below.

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SF-2040 User Guide – Rev. F

Figure 8: SF-2040 Block Diagram

Communication Port Connectivity

Connect the supplied LEMO 7-Pin connector of the
serial cable (P/N 94-310090-3003) to COM 2 (factory
default Control Port) of the SF-2040. Connect the
DB9S end to the control device.

 Some devices may require an additional

adaptor, as the receiver is configured as a

DCE device.

 COM 2 is the SF-2040 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

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SF-2040 User Guide – Rev. F

applications. Though Com 1 is physically
capable of operating at 115K baud, the
throughput from the GPS Engine to the IOP is
limited to 19.2K baud (refer to Figure 8).
Thus, the recommendation to maintain Com 2
as the Control port for multi-hertz applications.

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 input corrections. In the Base Station,
the NMEA port can not share the data port
with any RTCM, CMR, or NCT RTK output
corrections.

Refer to the Technical Reference Manual for
available port configuration settings.

Figure 9: Communication Port Connections

 Use the optional power cable

(P/N 94-310060-3010) to provide
external power to the SF-2040.
Chapter 2 Interfacing\Electrical Power
details construction specifications.

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SF-2040 User Guide – Rev. F

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SF-2040 User Guide – Rev. F

Chapter 4 ...............................Configuration

The SF-2040 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-2040:

9 StarUtil – This program is a NavCom developed

utility designed to configure and view many (but
not all) of the SF-2040 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-2040.

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-2040
(potentially in conjunction with other devices or
utilities). To facilitate this effort, NavCom has two
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-2040 User Guide – Rev. F

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.

4-48

Figure 10: StarUtil NMEA Message List

SF-2040 User Guide – Rev. F

Figure 11: 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-2040. COM1 also serves as the DGPS correction
input/output port when NCT, 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 10 describes the default
messages needed to best initiate surveying with
minimal effort.

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SF-2040 User Guide – Rev. F

The user has full control over the utilized message
types and their associated rates via either StarUtil or
a third party software/utility.

Table 10: 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-2040 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,
almanac source, almanac health, pages 1-25,
and sub-frames 4 and 5.

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SF-2040 User Guide – Rev. F

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-2000 or
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 (NCT-2000
or NCT-2100, 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.

3rd Party Controller Configuration Settings

Please refer to the third party controller solution
manual/user guide if your SF-2040 GPS sensor is
part of an integrated solution.

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SF-2040 User Guide – Rev. F

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SF-2040 User Guide – Rev. F

Chapter 5 .................... Safety Instructions

The SF-2040 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

If the SF-2040 is used with the optional external
power cable (P/N 94-310060-3010), it 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

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SF-2040 User Guide – Rev. F

allow sufficient current draw for proper operation.
Insufficient supplied current will cause damage to the
external power source.

If the chosen external power source is a disposable
battery, please dispose of the battery in accordance
with local regulations.

Battery Packs

The SF-2040 GPS sensor is supplied with two
lithium-ion battery packs.

Charge the battery packs only with the

supplied battery charger (P/N 92­310046-3001) and supplied charger
power supply (P/N 82-02003-5001);
otherwise, damage to the battery
packs could occur.

Do not store battery packs above 60°C

(140° F) or below -20°C (-4° F).

Do not disassemble or modify battery

packs; there are no user serviceable
parts inside.

The battery contains safety and
protection devices, which if damaged,
may cause the battery to generate
heat, explode or ignite.

Do not expose battery packs to fire;

this could result in an explosion, and
the release of toxic fumes.

Do not short circuit battery contacts. A

short circuit of the battery contacts
could result in an explosion, and the
release of toxic fumes.

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SF-2040 User Guide – Rev. F

In the event that the battery leaks and

the fluid get into one’s eye, do not rub
the eye. Rinse well with water and
immediately seek medical care. If left
untreated the battery fluid could cause
damage to the eye.

Misusing the battery may cause the battery to get hot,
explode, or ignite and cause serious injury. Follow the
safety rules listed below:

Do not install the battery backwards

so that the polarity is reversed.

Do not connect the positive terminal

and the negative terminal of the
battery to each other with any metal
object (such as wire).

Do not carry or store the batteries

together with metal objects that may
come in contact with the battery
terminals.

Do not pierce the battery with nails,

strike the battery with a hammer, step
on the battery, or otherwise subject it
to strong impacts or shocks.

Do not solder directly onto the battery.
Do not expose the battery to water or

salt water, or allow the battery to get
wet.

Do not place the battery on or near

fires, stoves, or other high temperature
locations. Do not use or store the
battery in any areas with excessive
heat, for example, the interior of a car

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SF-2040 User Guide – Rev. F

or truck in hot weather. Doing so may
cause the battery to generate heat,
explode, or ignite. Using the battery in
this manner may also result in a loss of
performance and a shortened life
expectancy.

This device is not to be used by small

children.

Immediately discontinue use of the

battery if, while using, charging, or
storing the battery, the battery emits
an unusual smell, feels hot, changes
color, changes shape, or appears
abnormal in any other way.

Do not place the batteries in

microwave ovens, high-pressure
containers, or on induction cookware.

 Battery Disposal

Dispose of battery packs properly;

cover the contacts with a non­conductive material and recycle.

 The Lithium-Ion battery packs are classified

by the United States Federal Government
as non-hazardous waste and are safe for
disposal in the normal municipal waste
stream per your local regulations. These
batteries, however, do contain recyclable
materials and are accepted for recycling by
the Rechargeable Battery Recycling
Corporation's (RBRC) Battery Recycling
Program. For additional information, go to
the RBRC website at

http://www.rbrc.org/call2recycle/index.html

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SF-2040 User Guide – Rev. F

 Battery Charging

Follow the rules listed below while charging the
battery. Failure to do so may cause the battery to
become hot, explode, or ignite and cause serious
injury.

Charge the battery packs only with the

supplied battery charger (P/N 92­310046-3001) and supplied charger
power supply (P/N 82-02003-5001);
otherwise, damage to the battery
packs could occur.

The temperature range over which the

battery can be charged is 0°C to 40°C.
Charging the battery at temperatures
outside of this range may cause the
battery to become hot or to break. It
may also harm the performance of the
battery or reduce the battery’s life
expectancy.

Do not attach the batteries to a power

supply plug or directly to a car’s
cigarette lighter.

Do not continue charging the battery if

it does not accept a charge within the
full charge cycle of 8 to 10 hours.
Doing so may cause the battery to
become hot, explode, or ignite.

If the battery packs are left charging

for longer than 5 days, the charging
indicator LEDs will shut off. If this
occurs, place the battery packs in the
SF-2040 GPS sensor and power on
for 10-15 minutes in order to slightly
discharge the batteries.

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SF-2040 User Guide – Rev. F

 Battery Discharging

The temperature range over which the

battery can be discharged is -20°C to
60°C. Use of the battery outside of this
temperature range may damage the
performance of the battery or may reduce
its life expectancy.

Do not discharge the battery using any

device other than the device it is designed
to operate with (i.e., the GPS sensor or
radio modem). Doing so may damage the
performance of the battery or reduce its
life expectancy, and may cause the
battery to become hot, explode, or ignite
and cause serious injury.

Remove the battery packs from the

SF-2040 GPS if the sensor will not be
used for over 1 week.

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-2040 GPS sensor. Accessing the inside of the
equipment will void the equipment warranty.

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SF-2040 User Guide – Rev. F

Take care to ensure the SF-2040 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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SF-2040 User Guide – Rev. F

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SF-2040 User Guide – Rev. F

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/

The SF-2040 GPS sensor is 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 Fully integrated receiver in robust housing
9 “All-in-view” tracking with 26 channels

(12 L1 GPS + 12 L2 GPS + 2 SBAS)

9 2 separate SBAS channels, RTCA/DO-229D

compliant (WAAS/EGNOS/MSAS/GAGAN)

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 Accepts external DGPS input in RTCM v2.3 or

CMR format

9 L1 & L2 full wavelength carrier tracking
9 C/A, P1 & P2 code tracking
9 User programmable output rates

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SF-2040 User Guide – Rev. F

9 Two “hot-swapable”, rechargeable, lightweight

battery packs

9 Minimal data latency
9 Superior interference suppression
9 Patented multipath rejection
9 Output of NMEA 0183 v3.1 messages
9 Self-survey mode (position averaging)

9 TruBlu™ Wireless Connectivity, Bluetooth®

compatible

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-2040 User Guide – Rev. F

1

Measurement Performance

Real-time StarFire™ SBAS Accuracy

Position (H):
Position (V):
Velocity:

<10 cm
<15 cm

0.01 m/s

Real-time WAAS/EGNOS/MSAS/GAGAN
SBAS Accuracy

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

Ultra-RTK Positioning <40km (RMS)

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)

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:

20cm @ 42 dB-Hz
L1: 0.95 mm @ 42 dB-Hz

L2: 0.85 mm @ 42 dB-Hz

Requires GPS software version 4.2 or higher

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SF-2040 User Guide – Rev. F

User programmable output rates

PVT 1, 2, 5Hz Standard

10 & 25Hz Optional

Raw data 1, 2, 5Hz Standard

10, 25, & 50Hz Optional

Data Latency

PVT < 20 ms at all nav rates
Raw data < 20 ms at all rates

Connector Assignments

Data Interfaces:

2 serial ports from 1200 bps to 115.2 kbps

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SF-2040 User Guide – Rev. F

Input/Output Data Messages

NCT Proprietary
Data

NMEA-0183
Messages

(Output Only)
Proprietary

NMEA-0183 Type
(Output Only)

Code Corrections RTCM 1, 3 & 9

RTK Correction
Data (I/O)

PVT ,
Raw Measurement
Satellite Messages
Nav Quality
Receiver Commands

ALM, GGA, GLL, GSA, GST,
GSV, RMC, VTG, ZDA

SET

WAAS/EGNOS/MSAS/GAGAN
StarFire™ (WCT)

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-2040
Configuration
(User Programmable)

Position Quality

SF-2040 User Guide – Rev. F

Satellite Based Augmentation System Signals

RTCA/DO-229D Standard
(WAAS/EGNOS/MSAS/GAGAN)
StarFire™

Physical and Environmental

Size (W x H): 10.4” x 5.5”

(264mm x 140mm)
Weight: 5.5 lbs (2.5 kg)
External Power:

Input Voltage:
Consumption:

Connectors:

I/O Ports:

DC Power:
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

-40º C to +55º C

-40º C to +85º C

A-66

SF-2040 User Guide – Rev. F

Battery Packs

Type: Lithium-Ion, Rechargeable
Size (L x W x H): 3.45” x 2.75” x 1.70“
Weight: 11 oz (0.312 kg)
Performance: > 10 hrs. on full charge

(> 5 hrs each battery)

Temperature (ambient)

Storage/Discharge:
Charger Operating:

Full Charge Cycle: 8 to 10 hours
Interface: Hot-swapable
Operating Power

Status:

-20º C to +60º C
0º C to +40º C

Indicator Panel LEDs

Battery Charger Kit

AC Input Voltage: 90-250 VAC
AC Current: 1.2 A max at 90VAC input
DC Output Voltage: 3.0 A max at 15VDC output
Display: LED Indications: Power On,

Charging, Charging

Complete
Size (L x W x H): 11” x 4.33” x 2.95”
Weight (Battery

Charger, Power
Supply and Cables):

2.5 lbs (1.2 kg)

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SF-2040 User Guide – Rev. F

This page is left blank intentionally

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SF-2040 User Guide – Rev. F

B........................... Antenna Specifications

Table 11: SF-2040 Integrated Antenna

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

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

 Designed to DO-160D Standard

B-69

SF er Guide – Rev. F -2040 Us

 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

Radiation Pattern

6.5dB @ 90º

24º

32º

-4dB @ 5º

0dB

07-00008-A

Figure 12: NAVSF2040G Radiation Pattern

Optimal antenna performance is realized at
elevations greater than 30º.

-4.5dB @ 5º

0dB

 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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SF-2040 User Guide – Rev. F

C .................................................StarFire™

Description

The StarFire™ Network is a global system for the
distribution of SBAS corrections giving the user the
ability to measure his 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-2040 User Guide – Rev. F

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-2040 User Guide – Rev. F

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-2040 User Guide – Rev. F

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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SF-2040 User Guide – Rev. F

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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SF-2040 User Guide – Rev. F

C-76

Figure 13: StarFire™ Network

SF-2040 User Guide – Rev. F

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-77

SF-2040 User Guide – Rev. F

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-78

SF-2040 User Guide – Rev. F

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-79

SF-2040 User Guide – Rev. F

`

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 14: 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-80

SF-2040 User Guide – Rev. F

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-2040 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.

Glossary-81

SF-2040 User Guide – Rev. F

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

Glossary-82

SF-2040 User Guide – Rev. F

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

Glossary-83

SF-2040 User Guide – Rev. F

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.

Glossary-84

SF-2040 User Guide – Rev. F

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

Glossary-85

SF-2040 User Guide – Rev. F

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

Glossary-86

SF-2040 User Guide – Rev. F

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

Glossary-87

SF-2040 User Guide – Rev. F

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
StarFire™, WAAS, EGNOS, MSAS, and GAGAN
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

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(see Appendix C).
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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