FirstGPS™ Starter Kit
User Guide
Version 1.0
Part Number 44326-00-ENG
Revision A
March 2001
ꢀ
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Warranty Exclusions and Disclaimer
TRIMBLE NAVIGATION LIMITED IS NOT
RESPONSIBLE FOR THE OPERATION OR
FAILURE OF OPERATION OF GPS
SATELLITES OR THE AVAILABILITY OF
GPS SATELLITE SIGNALS.
These warranties shall be applied only in the event
and to the extent that: (i) the Products and
Software are properly and correctly installed,
configured, interfaced, maintained, stored, and
operated in accordance with Trimble's relevant
operator's manual and specifications, and; (ii) the
Products and Software are not modified or
misused. The preceding warranties shall not apply
to, and Trimble shall not be responsible for defects
or performance problems resulting from (i) the
combination or utilization of the Product or
Software with products, information, data,
systems or devices not made, supplied or specified
by Trimble; (ii) the operation of the Product or
Software under any specification other than, or in
addition to, Trimble's standard specifications for
its products; (iii) the unauthorized modification or
use of the Product or Software; (iv) damage
caused by accident, lightning or other electrical
discharge, fresh or salt water immersion or spray;
or (v) normal wear and tear on consumable parts
(e.g., batteries).
Limitation of Liability
TRIMBLE’S ENTIRE LIABILITY UNDER ANY
PROVISION HEREIN SHALL BE LIMITED TO
THE GREATER OF THE AMOUNT PAID BY YOU
FOR THE PRODUCT OR SOFTWARE LICENSE OR
U.S.$25.00. TO THE MAXIMUM EXTENT
PERMITTED BY APPLICABLE LAW, IN NO
EVENT SHALL TRIMBLE OR ITS SUPPLIERS BE
LIABLE FOR ANY INDIRECT, SPECIAL,
INCIDENTAL OR CONSEQUENTIAL DAMAGES
WHATSOEVER UNDER ANY CIRCUMSTANCE
OR LEGAL THEORY RELATING IN ANY WAY TO
THE PRODUCTS, SOFTWARE AND
ACCOMPANYING DOCUMENTATION AND
MATERIALS, (INCLUDING, WITHOUT
LIMITATION, DAMAGES FOR LOSS OF
BUSINESS PROFITS, BUSINESS INTERRUPTION,
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OTHER PECUNIARY LOSS), REGARDLESS
WHETHER TRIMBLE HAS BEEN ADVISED OF
THE POSSIBILITY OF ANY SUCH LOSS AND
REGARDLESS OF THE COURSE OF DEALING
WHICH DEVELOPS OR HAS DEVELOPED
BETWEEN YOU AND TRIMBLE. BECAUSE
SOME STATES AND JURISDICTIONS DO NOT
ALLOW THE EXCLUSION OR LIMITATION OF
LIABILITY FOR CONSEQUENTIAL OR
THE WARRANTIES ABOVE STATE TRIMBLE'S
ENTIRE LIABILITY, AND YOUR EXCLUSIVE
REMEDIES, RELATING TO PERFORMANCE OF
THE PRODUCTS AND SOFTWARE. EXCEPT AS
OTHERWISE EXPRESSLY PROVIDED HEREIN,
THE PRODUCTS, SOFTWARE, AND
ACCOMPANYING DOCUMENTATION AND
MATERIALS ARE PROVIDED “AS-IS” AND
WITHOUT EXPRESS OR IMPLIED WARRANTY
OF ANY KIND BY EITHER TRIMBLE
INCIDENTAL DAMAGES, THE ABOVE
LIMITATION MAY NOT APPLY TO YOU.
NAVIGATION LIMITED OR ANYONE WHO HAS
BEEN INVOLVED IN ITS CREATION,
PRODUCTION, INSTALLATION, OR
DISTRIBUTION INCLUDING, BUT NOT LIMITED
TO, THE IMPLIED WARRANTIES OF
MERCHANTABILITY AND FITNESS FOR A
PARTICULAR PURPOSE, TITLE, AND
NONINFRINGEMENT. THE STATED EXPRESS
WARRANTIES ARE IN LIEU OF ALL
OBLIGATIONS OR LIABILITIES ON THE PART
OF TRIMBLE ARISING OUT OF, OR IN
CONNECTION WITH, ANY PRODUCTS OR
SOFTWARE. SOME STATES AND
JURISDICTIONS DO NOT ALLOW LIMITATIONS
ON DURATION OR THE EXCLUSION OF AN
IMPLIED WARRANTY, SO THE ABOVE
LIMITATION MAY NOT APPLY TO YOU.
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About This Manual
Related Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . x
1
Measurement Platform Module (MPM) . . . . . . . . . . . . . . 9
2
Running the FirstGPS Starter Kit for the First Time . . . . . . . . . . 14
Running the FirstGPS Starter Kit . . . . . . . . . . . . . . . . . . . . 16
FirstGPS Monitor Main User Interface . . . . . . . . . . . . . . . . . 17
Time [GPS]. . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
ENU Velocity [filt] . . . . . . . . . . . . . . . . . . . . . . . . 18
FirstGPS Starter Kit User Guide
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Configure Menu . . . . . . . . . . . . . . . . . . . . . . . . . 25
3
Software Integration
A
npChStatusType . . . . . . . . . . . . . . . . . . . . . . . . . 39
npCompTimeType . . . . . . . . . . . . . . . . . . . . . . . . 40
npDgpsCorrType . . . . . . . . . . . . . . . . . . . . . . . . . 40
npDopType . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
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Standard FirstGPS Events . . . . . . . . . . . . . . . . . . . . 58
FirstGPS API - Return Types . . . . . . . . . . . . . . . . . . . . . . 58
FirstGPS API - Function Descriptions . . . . . . . . . . . . . . . . . 59
navGetBbAddr . . . . . . . . . . . . . . . . . . . . . . . . . . 59
navGetChStatus . . . . . . . . . . . . . . . . . . . . . . . . . 60
FirstGPS Starter Kit User Guide vii
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navGetTempParams . . . . . . . . . . . . . . . . . . . . . . . 76
navGpsShutDown . . . . . . . . . . . . . . . . . . . . . . . . 79
navPutInitPosition . . . . . . . . . . . . . . . . . . . . . . . . 81
Glossary
Index
viii
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About This Manual
Welcome to the FirstGPS Starter Kit User Guide. This manual
describes how to install, set up, and use the FirstGPS™ Application
Programming Interface (API).
If you are not familiar with the Global Positioning System (GPS), visit
our Web site for an interactive look at Trimble and GPS at:
•
www.trimble.com
Trimble assumes that you are familiar with Microsoft Windows and
know how to use a mouse, select options from menus and dialogs,
make selections from lists, and refer to online help.
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Related Information
This manual is provided in portable document format (PDF).
Other sources of related information are:
•
Help – The software has built-in, context-sensitive help that lets
you quickly find the information you need. Access it from the
Help menu. Alternatively, click the Help button in a dialog, or
press [F1]. To access the What’s This? Help, click the question
mark in the top right corner of a dialog box then click the
relevant item.
•
•
Readme.txt file – A Readme.txt file contains information added
after the documentation was completed. To read this file,
double-click it or use a text editor to open it. The installation
program also copies this file into the program directory.
Release notes – The release notes describe new features of the
product, information not included in the manual, and any
changes to the manual. The release notes are provided as a .doc
file on the CD and are installed in the program directory
(typically C:\Program Files\Trimble\FirstGPS) when you install
the software. Use a text editor to view the contents of the
release notes.
•
•
ftp.trimble.com – Use the Trimble FTP site to send files or to
receive files such as software patches, utilities, service bulletins,
and FAQs. Alternatively, access the FTP site from the Trimble
Web site at www.trimble.com/support/support.htm.
Trimble training courses – Consider a training course to help
you use your GPS system to its fullest potential. For more
information, visit the Trimble Web site at:
–
www.trimble.com/support/training.htm
x
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Technical Assistance
If you have a problem and cannot find the information you need in the
product documentation, do one of the following:
•
Send an e-mail to:
•
•
Contact support at one of the numbers listed in the front section
of this manual.
Request technical support using the Trimble Web site at:
www.trimble.com/support/support.htm
Your Comments
Your feedback about the supporting documentation helps us to
improve it with each revision. To forward your comments, do one of
the following:
•
Send an e-mail to:
•
Complete the Reader Comment Form at the back of this
manual and mail it according to the instructions at the bottom of
the form.
If the reader comment form is not available, send comments and
suggestions to the address in the front of this manual. Please mark it
Attention: Documentation Group.
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About This Manual
Document Conventions
The document conventions are as follows:
Convention
Definition
Italics
Identifies software menus, menu commands,
dialog boxes, and the dialog box fields.
Represents messages printed on the screen.
Helvetica Narrow
Helvetica Bold
Identifies a software command button, or
represents information that you must type in a
software screen or window.
Identifies the sequence of menus, commands, or
dialog boxes that you must choose in order to
reach a given screen.
‘Select Italics / Italics’
[Ctrl]
Is an example of a hardware function key that you
must press on a personal computer (PC). If you
must press more than one of these at the same
time, this is represented by a plus sign, for
example, [Ctrl]+[C].
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1
FirstGPS Starter Kit Overview
1.1
Purpose of the Starter Kit
FirstGPS™ technology is designed for customers who need a simple
Global Positioning System (GPS) chipset in their applications.
The Starter Kit is for evaluation of FirstGPS software performance.
The Starter Kit includes:
•
•
A sample hardware board
A sample hardware environment, including antenna, power, and
serial communications
•
•
•
A sample Windows software application (Microsoft®
Windows 95 / Windows 98 / Windows NT / Windows 2000)
Sample source code for a typical application with examples of
API calls
This manual in PDF format on the supplied CD
Together, these give a preliminary view of the hardware and software
interfaces and provide the basis for a high-level discussion of
hardware and software integration issues.
1.2
FirstGPS Architecture
With FirstGPS software, the Position-Velocity-Time (PVT) solution is
accessed directly by the host application through calls to an
Application Programming Interface (API). This is a significant
departure from past practice, where the GPS function was usually a
PVT-serial solution, that is, a complete GPS receiver board that
generated the Position Velocity Time (PVT) fix, and then
communicated the PVT fix to the host application through a serial
port. The API-based design offers considerably more flexibility for the
applications designer, along with benefits in terms of size, power,
and cost.
2
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FirstGPS Starter Kit Overview
1
The FirstGPS architecture is built around three components designed
by Trimble:
•
•
•
Colossus™ Radio Frequency (RF) ASIC
IO Digital Signal Processing (DSP) ASIC
1
FirstGPS software library
2
The Colossus and IO chips are the center of the GPS function
hardware core. The FirstGPS library is the software interface with the
GPS function hardware core, and it is linked into the customer’s
software application.
A complete FirstGPS implementation comprises the following
components:
•
•
•
•
Power
Antenna and low-noise amplifier (LNA)
The GPS function hardware core
The host software application (Application Layer and
FirstGPS library)
1.
The FirstGPS software library is sometimes referred to as simply the
FirstGPS library.
2.
The IO chip (pronounced EEH-ooh) is named after the moon of Jupiter,
whose discovery (along with the three other Galilean moons) was one of the
landmarks in the history of navigation. By marking the Jovian lunar
transits/eclipses (Galileo estimated there are three per day on average), two
navigators can easily synchronize their timepieces. This established the first
anywhere, anytime time standard. Since the measurement of time is
equivalent to the measurement of longitude, observation of the Jovian moons
allowed absolute accurate positioning for the first time in the history of man.
For a more detailed account of Galileo’s discovery, and the invention of the
chronometer which eclipsed his discovery, see Longitude: The True Story of
a Lone Genius Who Solved the Greatest Scientific Problem of His Time,
Dava Sobel, 1995.
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FirstGPS Starter Kit Overview
1.2.1
Input/Output Interface
The Starter Kit contains a complete sample FirstGPS implementation,
described in Starter Kit Components, page 9. The sample hardware
core is the Measurement Platform Module (MPM), described on
page 9. The sample host software application is a Windows-based
program described in detail in Chapter 2, Using the Starter Kit. The
sample power interface, antenna interface, and the serial interface
between MPM and host CPU are provided by the motherboard
housing the MPM.
FirstGPS Hardware Core
There are two FirstGPS ASICs, an RFIC (Colossus) and a DSP ASIC
(IO). These two chips—combined with a voltage regulator, a Surface
function hardware core. Figure 1.1 shows the block diagram of this
hardware core.
The MPM in the FirstGPS Starter Kit is a sample board layout of the
GPS hardware component. The MPM board is described in
Measurement Platform Module (MPM), page 9. Layout depends upon
the customer’s application. Proper board layout is crucial to good
RF performance.
4
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FirstGPS Starter Kit Overview
1
BBI
FILT
BBQ
FILT
V_RF
Vcc
LI BLOCK
RF+
RF-
Fr
Matching
Network
SAW
FILTER
Colossus
RF ASIC
12.504 MHZ
XTAL OSC
RF IN
Q
I
Fs Fr
V_RF
TxD
RxD
PPS
VOLTAGE
Vcc
IO
REGULATOR V_CORE
DSP ASIC
and
COOLRISC
TEMP
SENSE
Figure 1.1
Colossus / IO Block Diagram
Power
The hardware core requires three voltages:
Hardware Core
VCC
Voltage
3.3 ±0.3 VDC
3.0 ±0.3 VDC
2.0 ±0.2 VDC
V_RF
V_CORE
In a typical implementation, 3.3 VDC is supplied to VCC and a
voltage regulator distributes the voltage to the various components
as required.
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Oscillator
The Local Oscillator (LO) for FirstGPS can be either 12.504 MHz or
13.000 MHz. The crystal must be accurate to within 10 PPM. Trimble
recommends a Temperature-Compensated Crystal Oscillator (TCXO).
Colossus RFIC
The GPS signal conversion from an analog signal to digital data is
performed by the Colossus RF ASIC. This ASIC contains a two-stage
down-converter using a 1400 MHz VCO located inside the chip. The
first conversion brings the GPS signal from 1575.42 MHz (L1) to an
Intermediate Frequency (IF) of 175.42 MHz. The second conversion is
to the pseudo-base band frequency of 84 kHz. After the second
conversion, the GPS signal is divided into I and Q bits which are in
phase-quadrature with respect to each other. The I and Q bits are
passed through a low-pass filter off chip, brought back in to a limiting
amplifier, and then sampled before being passed onto the IO DSP. The
external LO frequency divided by four. For a 12.504 MHz system the
sampling frequency would be 3.126 MHz.
Note – Keep all of the above frequencies in mind for EMI purposes
when doing system design.
All three voltages listed in Power, page 5 are supplied to Colossus to
feed the separate sections of the IC, VCC_RF for the RF conversion,
VCC_DIG for the digital dividers, and VCC_OUT for the I and Q
output buffers.
IO DSP
The GPS signal-processing function is performed by the IO DSP. This
ASIC contains the GPS correlation channels and a small CoolRISC
processor core with its own RAM and ROM. The CoolRISC runs the
tracking loop code that controls the correlators.
6
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FirstGPS Starter Kit Overview
1
The FirstGPS architecture is different from most GPS receiver
architectures. In all modern GPS architectures, the software resides in
a multitasking environment. The tasks perform a variety of functions,
including:
•
•
•
•
tracking loop control
measurement conditioning
position computations
navigation data decoding
The highest priority task is the signal-processing code (tracking
loops). This code, although it has a small code footprint, has a very
high interrupt rate (up to 2000 Hz) with a stringent latency
requirement. The rest of the tasks can loosely be grouped as
navigation code. These form a larger body of code, heavy with
floating-position operations, but with higher tolerance to latency.
In typical GPS board implementations, all tasks are hosted in the same
CPU even though they have significantly different characteristics. In
contrast, the FirstGPS architecture hosts the signal-processing
function on the IO and the navigation function on a host CPU,
allowing the processor characteristics to be optimized for each
function and reducing total system loading.
IO Interfaces
The outputs of the IO tracking loops are sent via serial link to the host
CPU, where the FirstGPS navigation code resides. There, the raw
outputs from IO are processed into range, Doppler, and orbit data
information, and then further processed into a PVT solution. These
results are made available through a fully featured FirstGPS API to the
host application. In the reverse direction, IO receives tracking loop
controls from the FirstGPS software via the serial link. The serial link
rate between IO and host CPU is typically 19200 baud.
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FirstGPS Starter Kit Overview
The IO has a Pulse-per-Second (PPS) function. One of the IO pins is
held high for approximately 5 microseconds at the start of every UTC
second. An API call is available to apply a small time bias, typically
an advance of a few microseconds, to account for cable lengths.
The IO also has a temperature function. Inside the IO chip is a
temperature-sensitive counter. An API call provides the counts in real-
time, and the counts can be converted into temperature using a simple
formula.
1.2.2
FirstGPS Software
The FirstGPS software library is the GPS function software core.
It resides on the host CPU, so it shares RAM and ROM with the
customer’s application. The library must be compiled specific to each
application, depending on the CPU, Real-time Operating System
(RTOS), and compiler. The source code is very portable, written in C,
environments. The FirstGPS software library encompasses the
complete software interface with the IO chip, so the IO is essentially
transparent to the application software.
A complete list of API calls for the FirstGPS software library is listed
in Appendix A, Using the FirstGPS API. In general, the application
program uses the FirstGPS API calls to:
•
•
Boot the IO and start the GPS function.
Initialize the receiver with non-volatile memory and current
time, if available.
•
Change receiver control parameters (satellite masks,
DGPS corrections).
•
•
•
•
Fetch current receiver status.
Fetch the most recent PVT solution.
Fetch ancillary data (for example, signal strengths).
Stop the GPS function.
8
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FirstGPS Starter Kit Overview
1
1.2.3
Application Layer
The term Application Layer is used to describe the host application
software. This is typically software running a navigation system, a
cellular wireless device, or any of a number of devices that benefit
from knowledge of position, running on a Real-time Operating System
(RTOS). This software provides at least the boot code and the user
interface, and it exercises the FirstGPS software library through the
function calls contained in the FirstGPS API.
1.3
Starter Kit Components
1.3.1
Measurement Platform Module (MPM)
The MPM board is a Trimble assembly designed for optimal
performance of the IO DSP and Colossus RF ASICs running at a
reference frequency of 12.504 MHz. A dual-output voltage regulator
is used to create the VCC_RF and VCC_Core needed to run both the
Colossus and IO DSP chips. The board size is a standard Trimble
form-factor of 32 mm x 66 mm. The antenna connector is a right-
angle, board-mounted MCX connector. I/O interfacing is through an
8-pin male header with the following pin identities:
Pin #
Function
Pin #
Function
1
2
3
4
No Connect
5
6
7
8
RXD
Power
PPS
TXD
SP_EN (Serial Port Enable)
GND
VCC_Ant (power for 5 V antenna)
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FirstGPS Starter Kit Overview
Figure 1.2 shows the top layout of Trimble’s MPM assembly:
Figure 1.2
Top MPM Assembly Layout
Figure 1.3 shows the bottom layout of Trimble’s MPM assembly:
Figure 1.3
Bottom MPM Assembly Layout
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FirstGPS Starter Kit Overview
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1.3.2
Motherboard
The MPM interface motherboard includes a +9 to +32 VDC input
software switching power supply that provides a regulated +3.3 VDC
to the MPM receiver. It also converts the TTL level I/O to RS-232 for
a direct interface to the computer. The motherboard provides an open
collector interface for the PPS. The input voltage must be between
+9 VDC and +32 VDC and is input to the board through a 3-pin
circular connector of which only two pins are used. Supplying power
outside the specified input range will damage the board.
Although there are two communication ports on the motherboard, only
one is available for use by the MPM (Port 1).
The pin identities for PORT 1 are:
Pin #
Function
NC
1
2
3
4
5
6
7
8
9
TX
RX
NC
GND
NC
NC
NC
PPS
Note – Due to the open-collector interface, through the 9-pin RS-232
port, the polarity of the PPS signal is inverted. The pulse is a 4 µs
negative-going pulse with the falling edge synchronized to UTC. When
removed from the motherboard, the receiver provides a positive-going
TTL level pulse, with the rising edge synchronized to UTC.
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FirstGPS Starter Kit Overview
1.3.3
Antenna
The Antenna supplied with the Starter Kit is a 3.3 VDC patch antenna
with integrated cable and connector for terminating to the interface
unit. This is an active antenna with +28 dB of gain. The MPM requires
approximately 10 dB to 14 dB of gain at the antenna connector on
board for best performance.
1.3.4
Power Supply
There are two ways to power the MPM Starter Kit using either the DC
power cable or the AC/DC converter.
For DC:
1. Connect the terminated end of the power cable to the power
connector on the interface unit.
2. Connect the red lead to positive voltage (+9 to +32 VDC).
3. Connect the black lead to GND.
The yellow lead is not used.
For AC:
1. Connect the output cable of the converter to the 3-pin power
connector on the interface unit.
2. Using an appropriate three-prong AC power cable (not
(110 VAC or 220 VAC).
1.3.5
Software
See Chapter 2, Using the Starter Kit.
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C H A P T E R
2
2
This chapter includes the following topics:
■ Touring the Sample Application
■ Running the FirstGPS Starter Kit for the First Time
■ Running the FirstGPS Starter Kit
■ FirstGPS Monitor Main User Interface
■ FirstGPS Monitor Features
■ Configuring FirstGPS Monitor for the Output Protocols
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2
Using the Starter Kit
2.1
Touring the Sample Application
This section provides a brief overview of the FirstGPS Starter Kit and
Monitor program.
The Monitor program is a graphical user interface (GUI) application,
which exercises the Trimble FirstGPS software library to generate
position, time, and velocity information in a user-friendly visual
Windows environment. The program allows performance evaluation
of the FirstGPS platform running on the Microsoft Windows 95, 98,
NT or 2000 operating environment.
2.2
Running the FirstGPS Starter Kit for the First Time
This section describes how to set up the FirstGPS Starter Kit.
(The FirstGPS Monitor program is referred to as the GUI.)
To set up the FirstGPS Starter Kit:
1. Connect the motherboard to a 9–32 VDC power supply.
2. Attach the antenna cable to the connector on the motherboard
and place the antenna where over half the sky is visible.
Note – Windows with reflective glass or wire mesh can
sometimes block the GPS signal.
3. Use an RS-232 cable to connect Port 1 on the motherboard to a
serial COM port on your PC.
4. Run the GUI.
The FirstGPS Starter Kit CD installs the GUI to your
C:\Program Files\Trimble\FirstGPS folder.
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Using the Starter Kit
2
If this is the first time the program has been run, the application
settings window shown below appears.
Be sure to select the correct application settings before running the
MPM kit:
1. Set the MPM Port to the name of the COM port on the PC used
to connect with the MPM.
2. Select the Save BBRAM on exit check box.
This will provide a faster Time to First Fix (TTFF).
3. Set Clock to 12.504 MHz.
4. Set Num Channels to 12.
5. Set Week epoch to 1024.
This includes all dates between August 22, 1999 and
March 2019.
To modify these or other application settings at a later time, from the
FirstGPS Monitor menu, page 17, select Configure / Settings.
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Using the Starter Kit
2.3
Running the FirstGPS Starter Kit
When the FirstGPS Monitor main window appears, shown on page 17,
the GPS engine is ready to start.
To launch the GPS engine (FirstGPS library):
•
Select Initialize / Start GPS.
If the application fails to initialize, a startup failed message is
displayed in the status bar on the bottom left of the main
window. If this occurs, please check that:
–
–
–
The COM port settings are correct in the application
settings.
The serial cable is connected between Port 1 of the MPM
and the PC’s COM port.
The MPM kit is powered up with a correct DC power
source.
To stop the GPS function after the GUI has been running:
•
Select Initialize / Stop GPS.
This shuts down the FirstGPS library and the MPM. You can
then exit the GUI.
Note – If the GUI is still running when the MPM unit is disconnected
from the power source, you must restart the GUI application.
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Using the Starter Kit
2
2.4
FirstGPS Monitor Main User Interface
The FirstGPS Monitor main window of the program, shown below, is
divided into eight sections. Once the GPS is running and the program
is communicating with the MPM kit, these sections are updated
dynamically with current GPS information.
2.4.1
Time [GPS]
The Time panel displays the following, relative to GPS or UTC
depending on the output options. (Refer to Timing Output, page 23.)
•
•
•
Date – month, day, and year
Week and TOW – the current GPS week number and time of
week respectively.
For more information, refer to navGetCompactTime, page 61.
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2.4.2
ENU Velocity [filt]
ENU Velocity is the current velocity (updated every second) in the
East-North-Up directions, in meters per second. For more information,
refer to navGetLastFix, page 66.
2.4.3
LLA Position [filt]
LLA Position is the current position (updated every second) in
Latitude-Longitude-Altitude coordinates. Units are degrees and
minutes relative to the WGS-84 datum. For latitude, N and S denote
North and South; for longitude, E and W denote East and West.
Altitude is computed in meters, referenced either to mean sea level or
to the WGS-84 ellipsoid depending on the output options. For more
information, refer to navGetLastFix, page 66.
2.4.4
Receiver Status
Receiver Status displays current receiver information:
•
•
Mode – the operating mode: 2D or 3D, Automatic or Manual
Almanac – the status of the collected GPS almanac pages
The window also shows how much of the almanac has been collected
and displays the message complete & current when the almanac collection
has been completed. For more information, refer to navGetNavStatus,
page 68, and navGetSvSelections, page 75.
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2.4.5
DOPs
DOPs is the abbreviation for Dilution Of Precision numbers. These
numbers are roughly associated with accuracy: the larger the numbers
are, the less accurate the fix is.
The two most useful numbers are Horizontal DOP (HDOP),
proportional to horizontal position accuracy, and Vertical DOP
(VDOP). Position DOP (PDOP) is for three-dimensional position
accuracy, and Time DOP (TDOP) is used for time accuracy. For more
information, refer to navGetLastFix, page 66, and to the Glossary.
2.4.6
Firmware Info
Firmware Info is the firmware version of the FirstGPS library and the
firmware version of the MPM. For more information, refer to
navGetNavVersion, page 69.
2.4.7
Satellite Data
Satellite Data is the current satellite tracking information for each
IO channel:
•
SV – satellite identifier (PRN). If the PRN is against a green
background, that satellite is usable for fixes.
•
•
•
Az. – azimuth
Elev. – elevation in degrees, if known. When elevation is
unknown, the value 90 or –90 is displayed.
For more information, refer to navGetChStatus, page 60 and
navGetSvSelections, page 75.
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2.4.8
Program Status
This section of the window has no title. It is located at the bottom of
the window. Program Status indicates:
•
•
•
•
Status of the serial connection between PC and MPM
Status of the FirstGPS library
Time since power-up
Name of the COM port on the PC
2.5
FirstGPS Monitor Features
The menu bar in the FirstGPS Monitor main window, page 17,
contains seven menus, as shown below.
The following sections describe these menus.
2.5.1
2.5.2
File Menu
Use File / Exit to close the FirstGPS Monitor window.
Initialize Menu
The following sections describe the six Initialize menu items.
Start / Stop GPS
When the GPS engine is not running, this menu item displays
Start GPS. To start the GPS engine, select this item.
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When the GPS engine is running, this menu item displays Stop GPS.
To stop the GPS engine, select this item. Stop GPS will also save
important parameters to Battery Backed-up RAM (BBRAM).
Cold Reset
Select Initialize / Cold Reset to restart the GPS engine and perform a
firmware reset after erasing all of the collected GPS data such
as the almanac and ephemeris. Cold resets result in a TTFF of
2 to 3 minutes.
Warm Reset
Select Initialize / Warm Reset to restart the GPS engine and perform a
firmware reset after erasing the ephemeris from the collected GPS
data. Performing a warm reset assumes that you have operated the
MPM long enough to collect almanac information and calculate PVT.
A typical warm reset results in a TTFF of about 50 seconds.
Hot Reset
Select Initialize / Hot Reset to restart the GPS engine and perform a
firmware reset without erasing any collected GPS data. Performing a
hot reset assumes that you have operated the MPM long enough to
collect almanac and ephemeris information and calculate PVT. A
typical hot reset results in a TTFF of about 15 seconds.
Set 2D Ref Altitude
Select Initialize / 2D Ref Altitude to prompt for a reference altitude for
the receiver while operating in the 2D mode.
PPS Output
Select Initialize / PPS Output to enable the PPS output on the
MPM board.
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2.5.3
View Menu
The following sections describe the sixteen View menu items.
Plots
Select View / Plots to display a Real-time Position Plot and a Real-time
Sky Plot.
Protocol Output
Select View / Protocol Output to view output data in the industry-
standard NMEA protocol in a separate window. Click Configure in
the output window to set up the protocol output options.
When you select to view NMEA output, the window displays ASCII
NMEA sentences.
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Position Output
Select View / Position Output to change the output position format,
either latitude / longitude / altitude or Cartesian Earth-Centered-Earth-
Fixed (ECEF) coordinates.
Velocity Output
Select View / Velocity Output to change the output velocity format,
either East / North / Up or ECEF coordinates.
Timing Output
Select View / Timing Output to change the output time format, either
GPS or UTC reference. The difference between UTC and GPS is
equal to the number of leap seconds added since 1970.
Signal Level Output
Select View / Signal Level Output to change the satellite signal level
output format to either AMU or CNO. For definitions of these terms,
see page 83.
The signal level is displayed in the Satellite Data section of the main
application window.
Almanac Pages
Select View / Almanac Pages to display GPS data for each of the
collected satellite almanac pages. Refer to the ICD-GPS-200
specification for definitions of the almanac terms.
Almanac Health
Select View / Almanac Health to display GPS data for the almanac
health page. For more information, refer to the npNavStatusType,
ulAlmHealthStatus parameter on page 47.
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Ephemeris Pages
Select View / Ephemeris Pages to display GPS data for each of the
collected satellite ephemeris pages. Refer to the ICD-GPS-200
specification for definitions of the ephemeris terms.
Ionosphere Info
Select View / Ionosphere Info to display GPS data for the ionospheric
model data page. Refer to the ICD-GPS-200 specification for
definitions of the ionosphere information terms.
UTC Page Info
Select View / UTC Page Info to display GPS data for the UTC data
page. Refer to the ICD-GPS-200 specification for definitions of the
UTC data terms.
GPS System Message
Select View / GPS System Message to display GPS system messages
for each satellite. Refer to the ICD-GPS-200 specification for
Oscillator Offset
Select View / Oscillator Offset to display the MPM’s oscillator bias
and drift (updated every second). For more information, refer to
navGetOscStatus, page 70.
Channel Tracking Status
Select View / Channel Tracking Status to hide or display the Satellite
Data section in the main window of the program. For more
information, refer to navGetChStatus, page 60 and
navGetSvSelections, page 75.
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Satellite Visibility
Select View / Satellite Visibility to display the Satellite Visibility
window which shows elevation angles of all satellites.
Temperature
Select View / Temperature to start the IO’s temperature sensor reports.
For more information, refer to navStartTempMeas, page 78 and
navGetTempParams, page 76.
2.5.4
Configure Menu
Receiver Configuration
Select Configure / Receiver Configuration to configure the FirstGPS
firmware parameters. For more information, refer to
navGetNavConfig, page 67.
Filter Configuration
Select Configure / Filter Configuration to configure the FirstGPS
filter parameters.
Protocol Configuration
Select Configure / Protocol Configuration to configure NMEA
protocol output options. For information on how to enable NMEA
output, see Configuring FirstGPS Monitor for the Output Protocols,
page 29.
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Data Logging
Select Configure / Data Logging to configure a data logging option.
You can log position fix data to a file in two different formats:
•
•
Tab-delimited ASCII text
Industry-standard NMEA ASCII text
Settings
Select Configure / Settings to configure the FirstGPS Monitor
parameters. The descriptions of the parameters in the Application
Settings window follow:
•
MPM Port – the serial communication port number to which the
MPM unit is connected through the RS-232 interface.
•
Application Port – The output protocols port settings. This must
be a port different from the MPM port. The PC must have at
least one more serial port (in addition to the one used for the
MPM port) to use the Output Protocols feature.
•
•
•
Append port # to logs – Select this check box to append the
MPM port number to the log file names, if any log options are
enabled through the Configure | Data Logging menu item.
Sync PC time to UTC – Select this check box to synchronize the
local PC time to UTC, once the MPM unit has started running
and the exact time is known.
Load BBRAM on start – This option enables loading the
BBRAM file to the FirstGPS library when connecting to the
MPM unit. The BBRAM file contains the GPS system data
such as:
–
–
–
–
the almanac
ephemeris
UTC
IONO(sphere) information
Loading the current BBRAM file allows for faster TTFF.
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This file does not come with the distribution of the FirstGPS
Monitor application. Rather, it is generated automatically when
the application runs for the first time and the Save BBRAM on
exit option is selected. Usually, it takes about 15 minutes of
tracking GPS signals before the BBRAM file is completely
filled with GPS almanac pages. On consecutive starts, if the
FirstGPS Monitor has been properly stopped (using the
Initialize / Stop menu item), the BBRAM file is saved in the
same directory as the GUI executable. Having this file available
at the next power-up makes the TTFF much faster.
•
•
•
Save BBRAM on exit – This option enables the generation of the
BBRAM file as described in the previous paragraph.
Smooth Dialog Resize – This option enables a smooth slide-out
effect when various GUI dialog boxes are displayed.
Clock – This option enables selection of the LO to 12.504 MHz
or 13.000 MHz. The MPM in the Starter Kit comes with a
12.504 MHz crystal. The FirstGPS library will not run unless
the Clock option is properly set.
•
•
Num Channels – This option enables selection of the number of
channels of the MPM unit. The MPM comes with 12 channels.
Week Epoch – This option enables selection of the week epoch
number, which is the number of 1024 week periods since
6 January 1980.
2.5.5
Tools Menu
The following sections describe the three Tools menu items.
TTFF Test Setup
Select Tools / TTFF Test Setup to configure and run a time-to-first-fix
(TTFF) test.
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TTFF Statistics
Select Tools / TTFF Statistics to display TTFF statistics.
Position Accuracy
Select Tools / Position Accuracy to display the position accuracy
relative to the specified reference position. By default, the reference
position is the first position fix generated by the FirstGPS library.
This feature is useful only when the MPM is stationary and its exact
position is known.
2.5.6
Window Menu
The Window menu offers one item:
Always On Top
Select Window / Always on Top to have the GUI window always
visible on the screen (never overlapped by other windows).
2.5.7
Help Menu
The Help menu offers two items:
Product Info
Select Help / Product Info to display product information. For more
information, refer to navGetNavVersion, page 69.
About
Select Help / About to display the About dialog with copyright and
contact information.
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2.6
Configuring FirstGPS Monitor for the
Output Protocols
The FirstGPS Monitor supports NMEA, the industry-standard ASCII
output protocol, which can be used through a serial interface from
a PC COM port.
To configure the FirstGPS Monitor for NMEA output, you must
specify the application port in the program settings using
Configure / Settings from the main menu. The application port must be
a COM port different from the one connected to the MPM unit. Set the
application port parameters as desired. The default NMEA parameters
are: 4800 baud, none, 8, 1.
NMEA outputs can be viewed on an ASCII terminal emulation
program, such as Hyperterm. This program is typically used on a
second computer. A single computer can be used provided that there
are three COM ports (one for MPM, one for NMEA protocol, and one
for the ASCII output program). An RS-232 null modem should be
used for PC-to-PC communications.
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Software Integration
3.1
Overview
The FirstGPS software library runs as a library to a host application
under a Real-Time Operating System (RTOS). This chapter discusses
a few of the design implementation issues.
3.2
Power-Up and Power-Down
The FirstGPS software is provided as a static library. It must be linked
with the user-defined application task (AppTask) to generate object
AppTask’s responsibility to start up and shut down the FirstGPS
engine as required. The two API functions navGpsStart, page 80, and
navGpsShutDown, page 79, are provided for that purpose.
Before any other API calls can be made, the AppTask must call
navGpsStart, page 80, once to power up the GPS engine. In response
to this call, two events are generated:
•
NAV_POWER_ON_ACK – The first event is generated
immediately after the call to navGpsStart and indicates that a
request to power up has been received, and that the GPS engine
is starting up.
•
NAV_START_UP_COMPLETE – The second event is
generated a few moments later to indicate that the FirstGPS
library and the IO have successfully started and are
running.This may take up to 3 seconds, depending on the
hardware and RTOS.
After the second event has been received, the AppTask may use other
FirstGPS API functions to retrieve library data. In addition, any API
calls that configure library components (such as the receiver or filter
configuration) must also be called at this time, if required.
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3
When GPS operation is not required, the library can be shut down to
decrease power consumption. To power down the library, the
application must call navGpsShutDown, page 79. In response to this
call, the NAV_READY_TO_SHUTDOWN event is generated as soon
as the library is completely shut down. It may take up to several
seconds before this event is generated.
3.3
Polled vs. Event-Driven Data Collection
The FirstGPS library provides facilities for both polled and event-
driven data collection.
•
Polled data collection involves the AppTask periodically calling
FirstGPS API functions to retrieve various data from the library
(position fix, almanac status, satellite data, and so on).
The AppTask assumes the responsibility of scheduling data
collection. This type of data collection is useful when
responding to manual requests for data, such as through a serial
cable, keyboard, or touch-screen interface. Polled data is also
useful when the AppTask has a timer-based scheduling
mechanism to periodically collect, store, and/or process the data
available through the API.
•
Event-driven data collection allows the AppTask to quickly
retrieve data through the API as soon as the data is generated by
new data is available while the library is running. For example,
every time the library computes a new position/velocity fix, a
The library can generate several different types of events. The
Standard FirstGPS Events table on page 58 lists all of them. Based on
the type of event generated, the AppTask calls a corresponding API
function to retrieve data associated with the event. The Event vs. API
Table, page 35, lists FirstGPS events and the corresponding API
function calls.
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Software Integration
Whenever an event is generated, the event data structure is stored
internally in a queue in the library. In order for the application task to
know which events have been generated, a special API function,
navGetEvent, page 63, is used to retrieve FirstGPS events. This
function blocks the calling task (for example, AppTask) until an event
is generated at which point the task is resumed.
In a typical application, the AppTask runs in a simple loop, calling
navGetEvent continuously. When an event is generated by the
FirstGPS library, the function returns the event information, allowing
the application task to call the API function corresponding to the
generated event and process the data. After the event-specific
processing is complete, the application task calls navGetEvent again
and repeats the loop.
Note – Event-driven data collection is the preferred method of using
the FirstGPS API calls. Trimble recommends that polled data
collection be used mainly when responding to queries for library data.
For example, when a New Position Fix Available event is generated,
generated position fix data. The application should avoid scenarios
where it constantly calls API functions, such as navGetLastFix on its
own (scheduled by a timer or while running in an infinite loop).
For information on how to retrieve events properly, refer to the
description of the API function navGetEvent, page 63 .
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3.4
Event vs. API Table
EVENT DESCRIPTION
EVENT ID
API
New position/velocity fix
available
NAV_FIX_NEW
navGetLastFix (page 66)
No new fix available
NAV_NO_FIX_NEW
n/a
New satellite tracking
selection
NAV_TRK_SELECTION_NEW
navGetChStatus (page 60)
New satellite fix
selection available
NAV_FIX_SV_SEL_NEW
NAV_REF_DCORR_NEW
NAV_POWER_ON_ACK
NAV_START_UP_COMPLETE
NAV_READY_TO_SHUTDOWN
NAV_START_UP_FAILED
NAV_TEMP_MEAS
navGetSvSelections
(page 75)
New differential
correction available
navGetDgpsCorrParams
(page 62)
Acknowledge to a
request to start GPS
navGpsStart (page 80)
navGpsStart (page 80)
navGpsShutDown (page 79)
navGpsStart (page 80)
FirstGPS library
successfully started
FirstGPS library
successfully shut down
FirstGPS library failed
to initialize and start
New temperature
measurement data
navGetTempParams
(page 76)
FirstGPS library fatal
error generated
NAV_FATAL_ERROR
n/a
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A P P E N D I X
A
A
Using the FirstGPS API
In this chapter:
■ Overview
■ Examples
■ FirstGPS API - Simple Data Types
■ FirstGPS API - Navigation Data Types
■ FirstGPS API - #define Directives and Enumerated Data Types
■ FirstGPS API - Return Types
■ FirstGPS API - Function Descriptions
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Using the FirstGPS API
1.1
Overview
This appendix describes the FirstGPS API data types, return types,
function descriptions, and so on.
1.2
Examples
Refer to the sample application source code on the CD-ROM shipped
with your Starter Kit. The examples illustrate how to use the API calls.
1.3
FirstGPS API - Simple Data Types
The table below describes all the simple data types defined within the
Navigation Platform.
Defined Data Type
Description
S8
Signed 8 bits integer.
U8
Unsigned 8 bits integer.
Signed 16 bits integer.
S16
U16
Unsigned 16 bits integer.
Signed 32 bits integer.
S32
U32
Unsigned 32 bits integer.
4 bytes single-precision floating point.
8 bytes double-precision floating point.
1 byte Boolean value.
FLT
DBL
BOOLEAN
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1.4
FirstGPS API - Navigation Data Types
The following subsections list all the data structures used for the
Navigation platform. All bit field descriptions assume the convention
that the least significant bit (LSB), the first bit, is bit 0.
1.4.1
npAllChStatusType
npAllChStatusType is used to report the tracking status of all
channels.
Data Type
Variable
Description
U32
ulGpsTowMsec
tChStatus[N_CHANNELS]
GPS time of week in milliseconds.
npChStatusType
Individual satellite tracking status. For
details, refer to npChStatusType in the
table below.
1.4.2
npChStatusType
npChStatusType describes the tracking status for a channel.
Data Type
Variable
ucSvId
Description
U8
U8
SV prn number.
ucNavStatus
Describes navigation status. For the
possible values and description, see
Navigation Status Code, page 52.
U8
ucAmu5
sCno
SNR in units of 0.2 AMU per bit.
S16
SNR in units of CNO. The range is
0 to 47.
U16
U16
usReserved
Reserved for future use.
usMeasStatus
Describes measurement status. For all
the possible values and descriptions,
see Channel Status Code, page 52.
FLT
FLT
fltAzimuth
fltElev
Azimuth in radians.
Elevation in radians.
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1.4.3
npCompTimeType
npCompTimeType defines a minimal set of clock/time fields that can
be used to do conversions between GPS time and SCOUNT.
Data Type
Variable
Description
U32
U16
U16
U8
ulMsecs
GPS week number.
SCOUNT value.
usWeeks
usRefScount
ucStatus
Status of the time. For all the possible
values and descriptions, refer to Time
Status Code, page 57.
1.4.4
npDgpsCorrType
npDgpsCorrType describes the differential correction block.
Data Type
U8
Variable
ucSvId
ucIod
Description
Satellite ID.
Issue of data.
U8
DBL
dblTime
Correct time tag; GPS time of week in
seconds.
U32
ulTimeOfReception
Time of reception; GPS time of week in
milliseconds.
FLT
FLT
fltPrc
fltRrc
Pseudorange correction in meters.
Range rate correction in
meters/second.
FLT
FLT
fltRrcDot
Acceleration correction in
meters/second .
2
fltPrcErrEst
1-sigma pseudorange correction error
estimate in meters.
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1.4.5
npDopType
npDopType contains a set of DOP (dilution of precision) parameters.
Data Type
Variable
fltPDOP
fltHDOP
fltVDOP
fltTDOP
Description
Position DOP.
Horizontal DOP.
Vertical DOP.
Time DOP.
FLT
FLT
FLT
FLT
1.4.6
npErrorEstType
npErrorEstType stores the system estimate of error of the produced
fix. These are 1-sigma values and are computed based on the expected
error from each satellite and the geometry of the constellation in use.
Data Type
FLT
Variable
flt3D
Description
Total position error in meters.
Horizontal position error in meters.
Vertical position error in meters.
Time bias error in meters.
FLT
fltHoriz
fltVert
FLT
FLT
fltTime
1.4.7
npFixChType
npFixChType stores channel-dependent fix data.
Data Type
FLT
Variable
Description
fltReserved[N_CHANNELS+1]
sCno[N_CHANNELS]
Reserved for future use.
S16
CNO of SVs used in fix. The range is
0 to 47.
U8
U8
U8
ucSvUsed[N_CHANNELS]
ucIode[N_CHANNELS]
ucAmu5[N_CHANNELS]
ID of satellites used.
IODE of satellites used.
AMU*5 of SVs used in fix. The range is
0-16*5=80.
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1.4.8
npFixSvSelType
npFixSvSelType describes the current constellation of satellites used
in the current position fix.
Data Type
Variable
Description
U8
U8
U8
U8
ucStatus
Satellite status code. For all the
possible values and descriptions, refer
to Satellite Status Code on page 57.
ucDimMode
ucDgpsMode
ucSatCnt
Operating dimension mode. For all the
possible values and descriptions, refer
to Operating Dimension on page 53.
Differential GPS mode. For all the
possible values and descriptions, refer
to, DGPS Operating Mode on page 52.
Number of satellites in the
constellation.
S8
cSvUsed [N_CHANNELS]
tDop
A list of SVs in the constellation.
npDopType
Dilution of precision numbers. For more
information, refer to npDopType,
page 41.
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1.4.9
npFixType
npFixType is used to store fix data.
Data Type
Variable
Description
DBL
dblPosLLA[3]
[0]—Latitude in radians. The range is
from –π/2 to +π/2.
[1]—Longitude in radians. The range is
from –π to +π.
[2]—Altitude above Datum ellipsoid
in meters.
FLT
fltVelEnu[3]
tErrorEst
[0]—East.
[1]—North.
[2]—Up velocities
in meters/second. The range is from
0.0 to +300.0.
npErrorEstType
Solution 1-sigma error estimate
numbers. For more information, refer
to npErrorEstType, page 41.
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1.4.10
npNavConfigType
npNavConfigType contains a set of parameters which maintains the
configuration of a GPS receiver.
Data Type
Variable
Description
FLT
FLT
FLT
FLT
FLT
fltElevMask
fltAmuMask
fltDopMask
fltPdopSwitch
fltMaxOscOffset
Elevation mask. (Radians 0.0 – π/2).
AMU mask.
DOP mask.
PDOP 2D/3D switch level.
oscillator is +/- fltMaxOscOffset from
nominal. The larger the value, the
longer it takes to acquire. Units are df/f.
U8
U8
U8
ucOprtngDim
ucDgpsCfg
Operating dimension. For all the
possible values, refer to Operating
Differential GPS configuration mode.
For all the possible values, refer to
DGPS Configuration Mode, page 53.
ucDynamics
Receiver modes. For all the possible
values, refer to Dynamic Mode Flag,
page 53.
U8
U8
ucDgpsAgeLlimit
ucLpFixRate
DGPS correction age threshold in
seconds.
RF sequencing rates.
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1.4.11
npNavFixType
npNavFixType is used to store and report all pertinent information
about the current fix.
Data Type
Variable
Description
npFixChType
npFixType
npFixType
DBL
tFixCh
Channel dependent fix information.
Raw position in latitude, longitude, Datum alt.
Filtered position in latitude, longitude, Datum alt.
Altitude conversion from Datum to MSL.
Raw ECEF position.
tRawFix
tFiltFix
dblDatumToMslAlt
dblPosECEF[3]
fltVelECEF[3]
dblOscBias
fltOscFreq
dblTimeTag
DBL
FLT
Raw ECEF velocities.
DBL
Oscillator bias in meters.
FLT
Oscillator frequency in meters/second.
DBL
GPS time of fix in seconds. The range is from 0 to
604799.
U16
usWeekTag
tDop
GPS week of fix.
npDopType
Dilution of precision numbers. For more
information, refer to npDopType, page 41.
S16
U8
sDatumIndex
ucNumSvsUsed
ucStatus
0 = WGS84 = default.
Number of SVs used.
U8
Indicates the validity status of this fix. For more
information, refer to Position Fix Status, page 55.
U8
U8
ucSource
Indicates the source of this position fix. For more
information, refer to Position Fix Source, page 54.
ucDgpsFlag
Differential GPS status. For more information,
refer to Position Fix DGPS Status, page 55.
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1.4.12
npNavStatusType
npNavStatusType contains a set of status words for the following
important data items:
•
GPS position availability – Specifies the state of the GPS
position solution, that is, whether any position is available for
use by the receiver or its source, and whether it came from
outside the receiver or was computed internally.
•
•
GPS time availability – Specifies the state of the GPS time
solution, that is, whether the time came from outside the
receiver, from one satellite, or from a GPS fix.
Receiver oscillator frequency offset availability – Specifies
whether the receiver has an estimate of its oscillator frequency
offset and where it came from.
•
•
Memory – Specifies if any non-volatile memory was available
when the receiver began the current start-up cycle.
Ephemeris – Each bit in this variable represents the ephemeris
status of a particular satellite (1-32). The bit is one (1) if the
ephemeris is in memory and valid. Otherwise the bit is zero (0).
This field can be used to determine quickly if the receiver needs
ephemeris data.
•
Almanac – Specifies the current status of the almanac.
A field similar to the one described above is also available for
the almanac to determine quickly if the receiver needs
almanac data.
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Data Type
Parameter
Description
U32
ulEphStatus
The ephemeris status from the navigation platform. The
least significant bit (LSB) represents the ephemeris
status for satellite 1, and the most significant bit (MSB)
represents satellite 32. The value 1 indicates that the
ephemeris is present and that it is valid; whereas 0
indicates that the ephemeris is not present or that it
is invalid.
U32
ulAlmPageStatus
The almanac page status from the navigation platform.
The LSB represents the ephemeris status for satellite
1, and the MSB represents satellite 32. The value 1
indicates that the almanac has been collected; whereas
0 indicates that the almanac has not been collected.
The almanac page being collected does not mean that
the satellite is healthy. See ulAlmHealthStatus below for
health status information.
U32
ulAlmHealthStatus
The almanac health status from the navigation
platform. The LSB represents the almanac status for
satellite 1, and the MSB represents satellite 32. The
value 1 indicates that the satellite is unhealthy; 0
indicates otherwise (the satellite is healthy or
information has not been collected yet).
U8
U8
U8
ucPosStatus
ucTimeStatus
ucOscStatus
possible values, refer to Position Status Code, page 56.
The time status from the navigation platform. For all
possible values, refer to Time Status Code, page 57.
The oscillator status from the navigation platform. For
all possible values, refer to Oscillator Status Code,
page 54.
U8
U8
ucMemStatus
ucAlmStatus
either zero or non-zero, where non-zero indicates that
the memory contents are valid and zero indicates that
the contents are invalid.
The almanac status from the navigation platform. For
all possible values, refer to Almanac Status Code,
page 50 .
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1.4.13
npOscStatusType
npOscStatusType is a set of parameters describing the oscillator. The
parameters, ucHaveBias and ucHaveFreqOffset, are flags indicating
the current condition of the oscillator. For all the possible values, refer
to Oscillator Status Code, page 54.
Data Type
Parameter
dblBias
Description
DBL
DBL
Oscillator bias in meters.
dblFreqOffset
Oscillator frequency offset in
meters/second.
FLT
FLT
fltBiasUnc
Oscillator bias uncertainty in meters.
fltFreqOffsetUnc
Oscillator frequency offset uncertainty
in meters/second.
U8
U8
ucHaveBias
Status flag indicating validity of bias.
For all possible values, refer to
Oscillator Status Code, page 54.
ucHaveFreqOffset
Status flag indicating validity of drift.
For all possible values, refer to
Operating Dimension, page 53.
1.4.14
npTempMeasType
npTempMeasType is a set of temperature measurement parameters.
Data Type
Variable
Description
U8
ucMsecInterval
The number of milliseconds over which
the temperature measurement was
made.
U32
U32
ulMeasMsec
ulMeasCount
The current GPS time when the
temperature measurement was made.
The measured TCO frequency (in
counts/ucMsecInterval). This value
varies with the temperature.
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1.4.15
npVersionTagType
npVersionTagType lists a complete description of a product version.
Data Type
Variable
cName[18]
ucMajor
ucMinor
ucBeta
Description
S8
U8
U8
U8
U8
U8
U16
Product name.
Major version number.
Minor version number.
Beta version. 0 if this is a final release.
Month of release.
ucMonth
ucDay
Day of release.
usYear
Year of release.
1.4.16
npVersionType
npVersionType stores the version number for the measurement
platform firmware, navigation platform API, navigation platform
software, native RTOS, and native processor. For a detailed
description, refer to npVersionTagType, page 49.
Data Type
Variable
Description
npVersionTagType tMpFwVer
npVersionTagType tNpApiVer
npVersionTagType tNpSwVer
npVersionTagType tRtosVer
npVersionTagType tCpuVer
Measurement platform version.
Navigation platform API version.
Navigation platform software version.
Native RTOS version.
Native processor version.
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1.5
FirstGPS API - #define Directives
and Enumerated Data Types
1.5.1
Event Handling Constants
Define
Value
Description
EVENT_NO_WAIT
0
For more information, refer to the lTimeOut
parameter of navGetEvent, page 63.
EVENT_WAIT_FOREVER
EVENT_GET_FIRST
EVENT_GET_LAST
-1
0
For more information, refer to the lTimeOut
parameter of navGetEvent, page 63.
For more information, refer to the ucGetFlag
parameter of navGetEvent, page 63.
1
For more information, refer to the ucGetFlag
parameter of navGetEvent, page 63.
1.5.2
Almanac Status Code
Define
Value
Description
NO_ALMANAC_DATA
HEALTH_PRESENT
ALM_PAGES_PRESENT
UTC_PRESENT
0
1
2
4
8
There is no almanac data in the database.
Indicates almanac health page is collected.
Almanac is complete and current.
Indicates UTC page is collected.
Indicates ionospheric page is collected.
IONO_PRESENT
For the almanac status flag, if the value is 0, then there is no almanac
data in the receiver. This is the normal situation after a cold reset. It is
possible that a complete almanac was not collected before the receiver
was turned off after a cold reset.
When the value is non-zero, some almanac pages are present in the
receiver.
A value of 15 indicates the desired condition, namely that the almanac
is complete and current.
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The four bit positions in the byte indicate the presence of certain data:
1. The bit with value 1 set means that the receiver has an almanac
health page. This page defines which satellites are present in the
current GPS constellation.
2. If the receiver has an almanac health page, and if it has an
almanac page for each satellite which is declared present, then
the bit with value 2 will be set.
3. If the receiver has the UTC page, then the bit with value 4 will
be set.
4. If the receiver has the IONO page, then the bit with value 8 will
be set.
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1.5.3
Channel Status Code
Define
Value
Description
STATUS_RESET
0
Know nothing condition.
MSEC ambiguity resolved.
Delta phase + range.
Phase, delta phase + range.
Resolved 1/2 cycle.
STATUS_TIME_KNOWN
STATUS_FREQ_LOCK
STATUS_PHASE_LOCK
STATUS_LOCK_POINT_KNOWN
STATUS_FRESH_MEAS
1
2
4
8
16
At least one measure in the last measured
period; measured period is the inverse of
the measurement rate.
STATUS_GOOD_PARITY
STATUS_VALID_MEAS
STATUS_HEALTHY
32
At least 1 good parity result.
64
Measurement passes “goodness” checks.
Satellite data = healthy.
128
1.5.4
Navigation Status Code
Define
Value
Description
EPH_DECODED
EPH_GOOD
1
Ephemeris has been decoded.
Ephemeris is good.
2
EPH_USED_IN_FIX
EPH_DGPS_CORR
16
32
Used in the current position fix
DGPS correction is available
1.5.5
DGPS Operating Mode
Define
Value
Description
DGPS_OFF
0
1
2
3
Differential GPS is off.
Set to differential GPS only.
Auto mode off.
DGPS_ONLY
DGPS_AUTO_OFF
DGPS_AUTO_ON
Auto mode on.
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1.5.6
DGPS Configuration Mode
Define
Value
Description
DGPS_CFG_OFF
DGPS_CFG_ONLY
DGPS_CFG_AUTO
0
1
2
Differential GPS is off.
Set to differential GPS only.
Auto mode.
1.5.7
Dynamic Mode Flag
Define
Value
Description
DYN_UNDEFINED
DYN_LAND
DYN_SEA
0
1
2
3
4
5
Undefined dynamics.
Land dynamics.
Sea dynamics.
DYN_AIR
Air dynamics.
DYN_STATIONARY
N_DYN
Stationary dynamics.
Total number of dynamic modes.
1.5.8
Operating Dimension
These definitions are used when setting the receiver's operation mode
or reporting fix satellite selection.
Define
Value
Description
DIM_2D
0
1
2
3
4
5
6
2D mode of operation.
3D mode of operation.
1SV mode of operation.
Auto mode of operation.
DGPS mode of operation.
2D Clock Hold mode of operation.
Over-determined clock mode.
DIM_3D
DIM_1SV
DIM_AUTO
DIM_DGPS_REF
DIM_2D_CLK_HOLD
DIM_OVERDET_CLK
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1.5.9
Oscillator Status Code
Status flag for the oscillator drift/bias used by the ucHaveFreqOffset
and ucHaveBias fields in npOscStatusType.
Define
Value
Description
HAOSC_UNKNOWN
HAOSC_OLD
0
1
2
3
4
No information.
Old.
HAOSC_FIX
Based on position/timing fix.
Approximate 1 SV solution.
Have knowledge from raw measurement.
HAOSC_APPX
HAOSC_MEAS
1.5.10
Position Fix Source
Source of the current position fix contained in the ucSource field of
the navFixType structure.
Define
Value
Description
FIX_SOURCE_NONE
FIX_SOURCE_INIT
0
1
No position in memory.
Position came from outside receiver and is
approximate.
FIX_SOURCE_ACCU
2
Position came from outside receiver and is
accurate to within 100 meters.
FIX_SOURCE_2D
FIX_SOURCE_3D
FIX_SOURCE_OLD
3
4
5
2D fix.
3D fix.
Fix is considered old, but is trusted from
selected satellites.
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1.5.11
Position Fix Status
Status of the current position fix contained in the ucStatus field of the
navFixType structure.
Define
Value
Description
FIX_STATUS_NONE
FIX_STATUS_OLD
0
1
No position in memory.
Fix is considered old, but is trusted from
selected satellites.
FIX_STATUS_NEW
2
Fix is valid and new.
1.5.12
Position Fix DGPS Status
Indicates if the position fix is differentially corrected.
Define
Value
Description
FIX_GPS_NOT_CORRECTED
FIX_DGPS_CORRECTED
0
1
Fix is not differentially corrected.
Fix is differentially corrected.
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1.5.13
Position Status Code
Status flag ucPosStatus has the following valid values. Only the
values (4–7) and (0x80+(4–7)) should be considered to indicate that a
valid position is available for output (navigation).
Define
Value
Description
HAVE_POS_NONE
HAVE_POS_INIT
0
1
No position in memory.
Position came from outside
receiver and is approximate.
HAVE_POS_ACCU
3
Position came from outside
receiver and is accurate to
within 100 meters.
HAVE_POS_FIX2A
HAVE_POS_FIX2M
HAVE_POS_FIX3A
HAVE_POS_FIX3M
HAVE_POS_DFIX2A
4
2D fix in auto 2D/3D mode.
2D fix in manual 2D mode.
3D fix in auto 2D/3D mode.
3D fix in manual 2D/3D mode.
5
6
7
(HAVE_POS_FIX2A | 0x80)
Same as HAVE_POS_FIX2A
but differential mode.
HAVE_POS_DFIX2M
HAVE_POS_DFIX3A
HAVE_POS_DFIX3M
HAVE_POS_OLD
(HAVE_POS_FIX2M | 0x80)
(HAVE_POS_FIX3A | 0x80)
(HAVE_POS_FIX3M | 0x80)
8
Same as HAVE_POS_FIX2M
but differential mode.
Same as HAVE_POS_FIX3A
but differential mode.
Same as HAVE_POS_FIX3M
but differential mode.
Fix is considered old, but is
trusted from selected satellites.
HAVE_POS_APPX
HAVE_POS_AVSV
HAVE_POS_FRIM
HAVE_POS_INTERNAL
9
Fix is converging.
10
11
12
Fix is converging.
Fix is converging.
Internal fix - not suitable for use.
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1.5.14
Satellite Status Code
Define
Value
Description
SCODE_DOING_FIXES
SCODE_GOOD_1SV
SCODE_NEED_TIME
SCODE_PDOP_HIGH
SCODE_BAD_1SV
SCODE_0SVS
0
1
2
3
4
5
6
7
8
9
10
Doing position fixes.
A usable SV is available.
Need GPS time.
PDOP is too high.
The chosen SV is unusable.
No usable satellites.
SCODE_1SV
Only one usable satellite.
Only two usable satellites.
Only three usable satellites.
Differential corrections.
Over-determined clock.
SCODE_2SVS
SCODE_3SVS
SCODE_DCORR_GEN
SCODE_OVERDET_CLK
1.5.15
Time Status Code
The time status flag has the following valid states. Only the highest
state should be considered valid for setting the application's real-time
clock.
Define
Value
Description
T_STATUS_NONE
T_STATUS_PROBLEM
T_STATUS_APPX
0
1
2
Time is unknown.
Error detected. Now being fixed.
Time is good to a few seconds, from
outside the receiver.
T_STATUS_SET
3
4
Time is good to ±10 msecs, from tracking
one satellite.
T_STATUS_BIAS_KNOWN
Time is good to ±1 µs, from a position fix.
npTimeStatusType is the type that enumerates the above constants.
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1.5.16
Standard FirstGPS Events
The following lists all of the standard events that the library could
possibly generate. For example, the event NAV_FIX_NEW indicates
that a new position fix has been generated.
Define
Value Description
NAV_FIX_NEW
10
11
12
13
15
20
New solution fix.
NAV_NO_FIX_NEW
Incapable of producing new fix.
New SV tracking selection.
New SV fix selection.
NAV_TRK_SELECTION_NEW
NAV_FIX_SV_SEL_NEW
NAV_REF_DCORR_NEW
NAV_POWER_ON_ACK
Newly generated differential correction.
Received request to turn on the FirstGPS
software.
NAV_START_UP_COMPLETE
NAV_READY_TO_SHUTDOWN
21
22
FirstGPS software started. Status valid.
FirstGPS software ended. User can shutdown
NAV_START_UP_FAILED
NAV_TEMP_MEAS
25
27
28
FirstGPS software startup failed.
Temperature measurement updated.
1
NAV_FATAL_ERROR
FirstGPS software fatal error generated.
1
NAV_FATAL_ERROR indicates that a fatal error has occurred, and that the library has been
shut down. To restart the library, call navGpsStart (page 80).
1.6
FirstGPS API - Return Types
The currently defined return types are:
Define
NAV_ERROR
Value Description
-1
0
A function call failed.
NAV_OK
A function call is successful.
Data retrieved is not complete.
NAV_INCOMPLETE
1
npRetCode is the FirstGPS API function return type that enumerates
the above values.
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1.7
FirstGPS API - Function Descriptions
1.7.1
navGetBbAddr
Get starting BBRAM address.
Description
The function navGetBbAddr provides the calling application with the
size and address location of the battery backed up memory (BBRAM)
section during the power-up or power-down sequence. During power-
up, it is called by the host application prior to calling the navGpsStart
function.
Included Header File
#include “npStdIface.h”
Format
npRetCode
navGetBbAddr (U8** ppucAddr, U32* pulSize);
OutPut Parameters
Data Type
Parameter
Description
U8**
ppucAddr
A pointer to a pointer which contains the
BBRAM beginning address updated by the
navigation platform.
U32*
pulSize
A pointer to U32 that has the size of the
entire BBRAM in bytes. This field is also
updated by the navigation platform.
Return Values
Value
Description
NAV_OK
The BBRAM address is retrieved
successfully.
NAV_ERROR
The BBRAM address is not retrieved
successfully.
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1.7.2
navGetChStatus
Get satellite tracking status.
Description
This function provides information (azimuth, elevation, AMU, and
so on) of the satellites currently being tracked from the navigation
platform. The data structure, npAllChStatusType, has two fields:
GPS time and an array of npChStatusType[N_CHANNELS], with
each entry corresponding to a channel. The data type,
npChStatusType contains all the tracking information for a channel.
Included Header File
#include “npStdIface.h”
Format
npRetCode
navGetChStatus (npAllChStatusType*
ptAllChStatus);
Output Parameter
Data Type
npAllChStatusType*
Parameter
Description
ptAllChStatus
A pointer to an application structure which
will be updated by the navigation platform.
For descriptions of each sub-field, refer to
npAllChStatusType, page 39 and
npChStatusType, page 39.
Return Values
Value
Description
NAV_OK
The tracking information is retrieved
successfully.
NAV_ERROR
The tracking information is not retrieved
successfully.
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1.7.3
navGetCompactTime
Get current time.
Description
The navGetCompactTime gets the current GPS week number and
GPS time of week from the navigation platform. The GPS time and
week number are computed based on the OS ticks elapsed since the
last time reported from the measurement unit.
Included Header File
#include “npStdIface.h”
Format
npRetCode
navGetCompactTime (npCompTimeType*
ptCompTime);
Output Parameter
Data Type
npCompTimeType*
Parameter
Description
ptCompTime A pointer to the npCompTimeType data
structure which includes various
representations of GPS time. Although
this function does not return a value,
check the ucStatus field of the
ptCompTime to determine whether the
ptCompTime contains a valid time or not.
Return Values
Value
Description
NAV_OK
NAV_ERROR
The GPS time is retrieved successfully.
The GPS time is not retrieved
successfully.
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1.7.4
navGetDgpsCorrParams
Get differential correction information.
Description
This function gets a copy of all the current differential correction
parameters available from the navigation platform’s database.
Included Header File
#include “npStdIface.h”
Format
npRetCode
navGetDgpsCorrParams (npDgpsCorrType
ptDgpsCorr[], U8* pucCount);
Output Parameters
Data Type
Parameter
Description
npDgpsCorrType
ptDgpsCorr[] A pointer to an array which contains the
results from the navigation platform. For
complete details, refer to
npDgpsCorrType, page 40.
U8*
pucCount
Indicates number of valid entries.
Return Values
Value
Description
NAV_OK
The differential correction parameters are
available.
NAV_ERROR
The differential correction parameters are
not available.
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1.7.5
navGetEvent
Retrieve a FirstGPS event.
Description
The events are queued up internally inside the FirstGPS library. To
retrieve the events in the FIFO order (First In First Out), pass
EVENT_GET_FIRST for ucGetFlag. Otherwise, use
EVENT_GET_LAST. This retrieves the most recent event.
If no events have been generated at the time when this function is
called, the calling task will be suspended until an event has been
generated. Pass the ID of the calling task in pvTaskId. This must be an
RTOS-specific pointer to a type of the task control block used by the
RTOS. This pointer will be cast to a task type relevant to the RTOS
which will allow the FirstGPS library to suspend the calling task.
lTimeOut specifies the timeout value in milliseconds after which the
suspended task will be resumed. If the task times out and no event has
been generated yet, NAV_ERROR is returned.
If some event has been generated before this function was called, the
event will be retrieved as specified by the ucGetFlag value and the
function will return immediately. Otherwise, the function will suspend
the calling task until either an event has been generated or the timeout
(lTimeOut) expired.
If an event has been retrieved successfully, the function returns
NAV_OK and updates pulEvent and pvEventData pointers with the
retrieved event and its data.
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Trimble recommends that the application have a task dedicated
exclusively to retrieving and processing FirstGPS events. For example,
the entry point of such a task would be:
void eventHandlerTask (void)
{
U32 ulEvent, ulEventData;
+/ Loop forever...
while (1)
{
// Retrieve the FirstGPS event
if (navGetEvent (>EventHandlerTask,
&ulEvent,
&ulEventData,
EVENT_WAIT_FOREVER,
EVENT_GET_FIRST) == NAV_OK)
{
processEvent (ulEvent, ulEventData);
}
// Here, sleep a little letting other tasks to complete.
// This is optional, and may not be required by the
// application.
Sleep (10);
}
}
Note – In the above example:
(1) gtEventHandlerTask is assumed to be a global variable of the task
control block type relevant to a native RTOS.
(2) The timeout value in navGetEvent() is specified as
EVENT_WAIT_FOREVER. This will suspend the event task until
an event has been generated. Trimble recommends this method for
retrieving events.
(3) Using the method in (2), EVENT_GET_FIRST should be used for
the ucGetFlag parameter. This will retrieve the events in the order in
which they were generated.
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Included Header File
#include “npStdIface.h”
Format
npRetCode
navGetEvent (void* pvTaskId, U32* pulEvent, void*
pvEventData, S32 lTimeOut, U8 ucGetFlag);
Input Parameters
Data Type
Parameter
Description
void*
pvTaskId
A pointer to a task control block of the
calling task.
S32
U8
lTimeOut
A timeout value.
ucGetFlag
Indicates the event retrieval method.
Output Parameters
Data Type
Parameter
Description
U32*
pulEvent
A pointer to a variable to be updated
with the event.
void*
pvEventData
A pointer to a variable to be updated
with data associated with the event.
Return Values
Value
Description
NAV_OK
NAV_ERROR
The event is retrieved successfully.
The event is not retrieved successfully.
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1.7.6
navGetLastFix
Get last position fix information.
Description
Gets a copy of the complete fix structure reflecting the last solution
fix. This contains various items including LLA and ECEF
position/velocity solutions, both raw and filtered, and their
uncertainties, clock bias, clock offset, list of satellites used, issue of
data (ephemeris) (IODE), and different mode flags.
The NAV_FIX_NEW event will be generated when a new position fix
is available.
Included Header File
#include “npStdIface.h”
Format
npRetCode
navGetLastFix (npNavFixType* ptNavFix);
Output Parameter
Data Type
Parameter
Description
npNavFixType*
ptNavFix
A pointer to the npNavFixType data structure, which
has various representations of navigation
information, updated by the navigation platform. For
detailed descriptions of each sub-field, refer to
npNavFixType, page 45.
Return Values
Value
Description
NAV_OK
The last position fix information is retrieved
successfully.
NAV_ERROR
The last position fix information is not retrieved
successfully.
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1.7.7
navGetNavConfig
Get receiver settings.
Description
This function gets a copy of the current GPS configuration.
Included Header File
#include “npStdIface.h”
Format
npRetCode
navGetNavConfig (npNavConfigType*
ptNavConfig);
Output Parameter
Data Type
npNavConfigType*
Parameter
Description
ptNavConfig
A copy of receiver configuration data to
be updated by the navigation platform.
Return Values
Value
Description
NAV_OK
The receiver configuration parameters
are available.
NAV_ERROR
The receiver configuration parameters
are not available.
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1.7.8
navGetNavStatus
Get navigation platform status.
Description
This function obtains a copy of the navigation status structure.
Included Header File
#include “npStdIface.h”
Format
npRetCode
navGetNavStatus (npNavStatusType* ptNavStatus);
Output Parameter
Data Type
npNavStatusType*
Parameter
Description
ptNavStatus
A structure containing Navigation
status parameters.
Return Values
Value
Description
NAV_OK
The Navigation status is obtained
successfully from the navigation
platform.
NAV_ERROR
The Navigation status is not obtained
successfully from the navigation
platform.
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A
1.7.9
navGetNavVersion
Get navigation platform version.
Description
This function gets a copy of the software version for the measurement
platform firmware, navigation platform API, navigation platform
software, native RTOS, and native processor.
Included Header File
#include “npStdIface.h”
Format
npRetCode
navGetNavVersion (npVersionType* ptVersion);
Output Parameter
Data Type
Parameter
ptVersion
Description
npVersionType*
A pointer to a version structure to be
updated by the navigation platform. For
detailed descriptions of each sub-field,
refer to npVersionType, page 49.
Return Values
Value
Description
NAV_OK
The firmware version is retrieved
successfully.
NAV_ERROR
The firmware version is not retrieved
successfully.
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1.7.10
navGetOscStatus
Get oscillator offset status.
Description
navGetOscStatus gets the navigation platform’s current estimates of
oscillator bias, frequency offset, and their uncertainties.
Included Header File
#include “npStdIface.h”
Format
npRetCode
navGetOscStatus (npOscStatusType* ptOscStatus);
Output Parameter
Data Type
npOscStatusType*
Parameter
Description
ptOscStatus
Contains oscillator and frequency
offset information. For a complete
listing, refer to npOscStatusType,
page 48.
Return Values
Value
Description
NAV_OK
The oscillator drift offset has been
retrieved successfully.
NAV_ERROR
The oscillator drift offset has not been
retrieved successfully.
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1.7.11
navInitTime
Put current time.
Description
Imports an external GPS time into the navigation platform. It adjusts
the local GPS time immediately, and the GPS time on the
measurement platform through message passing. The GPS time is
only permitted to override the current clock value if the current time
has not been set (that is, no satellites are tracked). The primary
purpose of this function is to reduce the time to the first fix.
Included Header File
#include “npStdIface.h”
Format
npRetCode
navInitTime (U16 usGpsWn, U32 ulGpsTowMsec,
FLT fltTimeAccuracy);
Input Parameters
Data Type
Parameter
usGpsWn
Description
U16
U32
GPS week number into the navigation platform.
ulGpsTowMsec
GPS time of week in millisecond into the
navigation platform.
FLT
fltTimeAccuracy
Accuracy of input time in milliseconds, -1 if
unknown.
Return Values
Value
Description
NAV_OK
NAV_ERROR
The GPS time is imported successfully.
The GPS time is not imported successfully.
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1.7.12
navPutDgpsCorrParams
Put differential correction information.
Description
This function puts a copy of all the current differential correction
parameters into the navigation platform’s database.
Included Header File
#include “npStdIface.h”
Format
npRetCode
navPutDgpsCorrParams (npDgpsCorrType
ptDgpsCorr[], U8 ucCount, U8 ucClearFlag);
Input Parameters
Data Type
Parameter
Description
npDgpsCorrType*
ptDgpsCorr
A pointer to an array which contains
the values to the navigation platform.
For complete details, refer to
npDgpsCorrType, page 40.
U8
U8
ucCount
Indicates number of valid entries.
ucClearFlag
Boolean:
TRUE: clears all previous entries.
FALSE: does not clear previous
entries.
Return Values
Value
Description
NAV_OK
The differential correction parameters
are imported successfully.
NAV_ERROR
The differential correction parameters
are not imported successfully.
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1.7.13
navPutNavConfig
Put receiver settings.
Description
This function imports a copy of the current GPS configuration into the
navigation platform.
Included Header File
#include “npStdIface.h”
Format
npRetCode
navPutNavConfig (npNavConfigType* ptNavConfig);
Input Parameter
Data Type
npNavConfigType*
Parameter
Description
ptNavConfig
A pointer to a new receiver
configuration structure.
Return Values
Value
Description
NAV_OK
The receiver configuration parameters
are imported successfully.
NAV_ERROR
The receiver configuration parameters
are not imported successfully.
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1.7.14
navPutOscFreqOffset
Put oscillator drift offset.
Description
navPutOscFreqOffset allows the user to override the startup value of
the oscillator frequency offset. This is of particular importance to
those systems that do not have battery backed-up RAM (BBRAM).
The current oscillator offset can be obtained from the
navGetOscStatus function.
Included Header File
#include “npStdIface.h”
Format
npRetCode
navPutOscFreqOffset (DBL dblFreqOffset, FLT
fltFreqSearch);
Input Parameters
Data Type
Parameter
Description
DBL
dblFreqOffset
New oscillator frequency offset will be
imported into the navigation platform in
(meters/second).
FLT
fltFreqSearch
The frequency to search around the
dblFreqOffset in (meters/second).
Return Values
Value
Description
NAV_OK
The new oscillator frequency offset has
been entered successfully.
NAV_ERROR
The new oscillator frequency offset has
not been entered successfully.
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1.7.15
navGetSvSelections
Get satellite selection.
Description
This function returns a list of satellites used for a position fix. The
structure, npFixSvSelType, has the current constellation of satellites
used in doing a position fix. It also contains modes of operation flags
and DOP values. Notice that a negative cSvUsed number indicates that
an SV was not included for the position fix calculation because of poor
integrity. For detailed descriptions, refer to npFixSvSelType, page 42.
Included Header File
#include “npStdIface.h”
Format
npRetCode
navGetSvSelections (npFixSvSelType* ptFixSvSel);
Output Parameter
Data Type
Parameter
ptFixSvSel
Description
npFixSvSelType*
A pointer to a data structure which
includes number of satellites, DOPs,
and modes of operation. Use the
ucStatus field of the structure to
determine the current status of the
navigation platform. For details, refer to
npFixSvSelType, page 42.
Return Values
Value
Description
NAV_OK
The npFixSvSelType structure has
valid data.
NAV_ERROR
The npFixSvSelType structure does
not have valid data.
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1.7.16
navGetTempParams
Get temperature data.
Description
The function navGetTempParams gets the temperature data from the
navigation platform. The data contain the following information:
•
•
•
The number of milliseconds over which the temperature
was made
The time in ulMeasMsec when the navigation platform received
the temperature measurement
The temperature measurement
The temperature measurement is really the number of counts of an
edge counter circuit on the measurement platform. The frequency of
the counter will vary as a function of temperature.
The NAV_TEMP_MEAS event will be generated when the
temperature measurement has been completed.
Included Header File
#include “npStdIface.h”
Format
npRetCode
navGetTempParam (npTempMeasType*
ptTempMeas);
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Output Parameter
Data Type
npTempMeasType*
Parameter
Description
ptTempMeas
The npTempMeasType has all the
temperature parameters for a
measurement. For more information, refer
to npTempMeasType, page 48.
Return Values
Value
Description
NAV_OK
A copy of temperature measurement data
is retrieved successfully.
NAV_INCOMPLETE
NAV_ERROR
The measurement requested is not
complete.
A copy of temperature measurement data
is not retrieved successfully.
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1.7.17
navStartTempMeas
Start temperature measurement.
Description
The function navStartTempMeas sends a message to the measurement
platform to perform a temperature measurement over the number of
milliseconds specified in the function call.
Included Header File
#include “npStdIface.h”
Format
npRetCode
navStartTempMeas (U8 ucMsecInterval);
Input Parameter
Data Type
Parameter
ucMsecInterval
Description
U8
The number of milliseconds over which
the temperature measurement is made.
Return Values
Value
Description
NAV_OK
The message is sent successfully to the
measurement platform.
NAV_ERROR
The message is not sent successfully to
the measurement platform.
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1.7.18
navGpsShutDown
Shutdown navigation platform.
Description
The shutdown function causes an immediate clearing of all the
resources allocated in the startup. It is important to call the shutdown
function before removing the power from a receiver. Failure to do so
causes a longer startup time on the subsequent start. It will take from
1 to 2 seconds to complete the shutdown.
Included Header File
#include “npStdIface.h”
Format
npRetCode
navGpsShutDown (void);
Parameters
N/A
Return Values
Value
Description
NAV_OK
The shutdown of navigation platform is
successful.
NAV_ERROR
The shutdown of navigation platform is
not successful.
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1.7.19
navGpsStart
Navigation platform startup.
Description
This is the entry point of the navigation platform. It creates all the
necessary tasks and allocates all the global resources used within the
navigation platform. It also has a set of input parameters, which allows
an application task to enter the initial time and accuracy of that initial
time, to reduce the time needed to determine the first fix.
Included Header File
#include “npStdIface.h”
Format
npRetCode
navGpsStart (FLT fltTimeAccuracy, U32 ulGpsMsec,
U16 usGpsWeek, U8 ucTimeStatus);
Input Parameters
Data Type
Parameter
Description
FLT
U32
U16
U8
fltTimeAccuracy Accuracy of time value input in milliseconds, –1 if unknown.
ulGpgMsec
usGpsWeek
ucTimeStatus
Approximate GPS time of week in milliseconds.
GPS week number.
A flag indicates whether or not the above values are
accurate. The value can be either TRUE, indicating that the
time is accurate, or FALSE, indicating that the time is
approximate. Ignore if fltTimeAccuracy is –1.
Return Values
Value
Description
NAV_OK
NAV_ERROR
The initialization of navigation platform is successful.
The initialization of navigation platform is not successful.
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1.7.20
navPutInitPosition
Input initial LLA position.
Description
The navPutInitPosition function allows the user to enter a known
position on startup to minimize the time needed for a first fix. The
initial position is an array of doubles, in the order of latitude, longitude
and altitude. The fltAccuFlag field determines whether or not the
input parameters are accurate.
Included Header File
#include “npStdIface.h”
Format
npRetCode
navPutInitPosition (DBL pdblPosLLA[ ], FLT
fltAccuFlag);
Input Parameters
Data Type
Parameter
Description
DBL*
pdblPosLLA
Initial position from user. This is an
array of three doubles, which has the
following order: latitude, longitude, and
altitude.
FLT
fltAccuFlag
Indicates the accuracy in meters. Value
0 means do not change, and all
negative values indicate not accurate.
Return Values
Value
Description
NAV_OK
The initialization of position is
successful.
NAV_ERROR
The initialization of position is not
successful.
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Glossary
This section defines technical terms and abbreviations used in
this manual.
AMU
A Trimble term: Arbitrary Measurement Unit. The AMU
is defined as: 20 (AMU) +22.8 = CNO
log10
where CNO = C/N , that is, the carrier-to-noise ratio.
0
ASIC
Application-specific integrated circuit.
ASCII
American Standards Committee for Information
Interchange. This organization established a hexadecimal-
computers to store character information.
API
Application Programming Interface.
BBRAM
Battery Backed-up RAM. See Start / Stop GPS, page 20
and Load BBRAM on start, page 26.
CNO
Carrier-to-noise ratio. See AMU.
Differential Global
Positioning System
(DGPS)
GPS positions can be differentially corrected (DGPS) in
real time (using radio telemetry) or through
postprocessing (no radio telemetry required).
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Glossary
Dilution of precision
(DOP)
A description of the purely geometrical contribution to the
uncertainty in a position fix, given by the expression:
DOP = SQRT TRACE (A)
T
-1
where: A = (G G) of G, the geometry matrix,
corresponding to the measurement connection matrix for
the instantaneous position solution (dependent on
1
satellite-receiver geometry) .
The DOP factor depends on the parameters of the
position-fix solution. Standard terms for GPS application
are:
Geometric DOP – Three position coordinates plus
clock offset in the solution.
Position DOP – Three coordinates.
Horizontal DOP – Two horizontal coordinates.
Vertical DOP – Height only.
Time DOP – Clock offset only.
1
Refer to Global Positioning System: Theory and
Applications, Volume I. Parkinson, Spilker, Axelrad, and
Enge (1996), p. 413.
DSP
DOP
Digital Signal Processor.
Dilution of precision.
Earth-Centered-Earth-
Fixed coordinates
The Cartesian coordinate system in which the X direction
is the intersection of the prime meridian (Greenwich) with
the equator. The vectors rotate with the earth. Z is the
direction of the spin axis.
ECEF
EMI
See Earth-Centered-Earth-Fixed coordinates.
Electromagnetic interference.
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Glossary
Global Positioning
System (GPS)
A system involving the use of satellite technology to
calculate an accurate three-dimensional position. A GPS
system consists of a space segment (up to 24 NAVSTAR
satellites in six different orbits), the control segment
(five monitor stations, one master control station and three
upload stations), and the user segment (GPS receivers).
NAVSTAR satellites carry extremely accurate atomic
clocks and broadcast coherent simultaneous signals.
Horizontal DOP
(HDOP)
See Dilution of precision.
ICD-GPS-200
GPS Interface Control Document, ICD-GPS-200, IRN-
200B-PR-00J, Rev. B-PR, U.S. Air Force, July 1, 1992.
Search for this document on the Web site:
http://www.space.com.af.mil/usspace/gps_support/
gps_documentation.htm.
IF
Intermediate frequency.
Issue of data (ephemeris).
Local oscillator.
IODE
LO
MPM
NMEA
Measurement Platform Module.
A standard established by the National Marine Electronics
Association (NMEA), that defines electrical signals, data
transmission protocol, timing, and sentence formats for
communicating navigation data between marine
navigation instruments.
PDOP
A measure of the quality of the GPS position. PDOP
values below 7 are satisfactory (the ideal PDOP value is
one, and values from 2 to 4 are good). See Dilution of
precision.
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Glossary
PRN
Pseudo random noise.
Position-Velocity-Time.
PVT
Real-time
This term means to be performed immediately, not at
some later time.
RFIC
RTOS
SAW
SV
Radio Frequency Integrated Circuit.
Real-time Operating System.
Surface acoustic wave.
Space vehicle, that is, GPS satellite.
See Dilution of precision.
TDOP
TTFF
TCO
TCXO
UTC
Time to First Fix.
Temperature-Compensated Oscillator.
Temperature-Compensated Crystal Oscillator.
Universal Time Coordinated; Universal Coordinated
Time.
VDOP
XTAL
See Dilution of precision.
Crystal, as used in Figure 1.1 on page 5, for example.
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Index
A
ALM_PAGES_PRESENT 50
Almanac 23, 46
Almanac status code 50
Antenna 12
Data logging 26
Data types 38
Date function 17
dblBias 48
dblDatumToMslAlt 45
dblFreqOffset 48, 74
dblOscBias 45
Application Layer 9
Application port 26
Application settings 26
Azimuth 19
dblPosECEF 45
dblPosLLA 43
dblTime 40
dblTimeTag 45
DGPS configuration mode 53
DGPS_AUTO_OFF 52
DGPS_AUTO_ON 52
DGPS_CFG_AUTO 53
DGPS_CFG_OFF 53
DGPS_OFF 52
Dilution of precision 19 41
,
DIM_1SV 53
DIM_2D 53
DIM_2D_CLK_HOLD 53
DIM_3D 53
DIM_AUTO 53
DIM_DGPS_REF 53
DIM_OVERDET_CLK 53
DSP ASIC 3
B
BBRAM 21, 26, 59
C
Channel status code 52
Channel tracking status 24
Clock 27
cName 49
Cold reset 21
Colossus RFIC 6
Configuration menus 25
CoolRISC 6
cSvUsed 42, 75
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Index
DYN_AIR 53
DYN_LAND 53
DYN_SEA 53
DYN_STATIONARY 53
DYN_UNDEFINED 53
Dynamic mode flag 53
fltAccuFlag 81
fltAmuMask 44
fltAzimuth 39
fltBiasUnc 48
fltDopMask 44
fltElev 39
fltElevMask 44
fltFreqOffsetUnc 48
fltHDOP 41
E
Elevation 19
Enumerated data types 50
EPH_DECODED 52
EPH_DGPS_CORR 52
EPH_GOOD 52
EPH_USED_IN_FIX 52
Ephemeris 46
fltHoriz 41
fltMaxOscOffset 44
fltOscFreq 45
fltPDOP 41
fltPdopSwitch 44
fltPrc 40
fltPrcErrEst 40
fltReserved 41
fltRrc 40
fltRrcDot 40
fltTDOP 41
Ephemeris pages 24
EVEN_WAIT_FOREVER 50
Event handling constants 50
EVENT_GET_FIRST 50, 63
EVENT_GET_LAST 50, 63
EVENT_NO_WAIT 50
Event-driven data collection 33
fltTime 41
fltTimeAccuracy 71 80
,
fltVDOP 41
F
Firmware information 19
FIX_DGPS_CORRECTED 55
FIX_GPS_NOT_CORRECTED 55
FIX_SOURCE_2D 54
FIX_SOURCE_3D 54
FIX_SOURCE_ACCU 54
FIX_SOURCE_INIT 54
FIX_SOURCE_NONE 54
FIX_SOURCE_OLD 54
FIX_STATUS_NEW 55
FIX_STATUS_NONE 55
FIX_STATUS_OLD 55
flt3D 41
GPS time availability 46
H
HAOSC_APPX 54
HAOSC_FIX 54
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HAOSC_MEAS 54
HAOSC_OLD 54
MPM pinouts 9
HAOSC_UNKNOWN 54
Hardware core voltages 5
HAVE_POS_ACCU 56
HAVE_POS_APPX 56
HAVE_POS_AVSV 56
HAVE_POS_DFIX2A 56
HAVE_POS_DFIX2M 56
HAVE_POS_DFIX3A 56
HAVE_POS_DFIX3M 56
HAVE_POS_FIX2A 56
HAVE_POS_FIX2M 56
HAVE_POS_FIX3M 56
HAVE_POS_FRIM 56
HAVE_POS_OLD 56
MPM port 26
N_DYN 53
NAV_NO_FIX_NEW 58
NAV_OK 58, 63
NAV_POWER_ON_ACK 32, 58
NAV_TEMP_MEAS 58, 76
navFixType 54, 55
HDOP, See Horizontal DOP
HEALTH_PRESENT 50
Help, context-sensitive x
Horizontal DOP 19 41
,
Hot resets 21
I
IO Interfaces 7
IONO page 51
IONO_PRESENT 50
Ionosphere information 24
navGetBbAddr 59
navGetCompactTime 61
navGetDgpsCorrParams 62
navGetEvent 63
navGetFixDgpsCorrection 35
navGetLastFix 34, 35, 66
navGetNavConfig 67
L
Latitude-Longitude-Altitude coordinates 18
least significant bit 39
navGetNavStatus 68
Local Oscillator 6
navGetNavVersion 69
lTimeOut 63, 65
navGetOscStatus 70, 74
navGetSvSelections 19, 35, 75
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Index
navGpsShutDown 32, 33, 35, 79
navGpsStart 32, 35, 59, 80
Navigation data types 39
Navigation status code 52
navInitTime 71
position 23
time 23
velocity 23
NavObject 7
navPutDgpsCorrParams 72
navPutInitPosition 81
navPutNavConfig 73
navPutOscFreqOffset 74
navStartTempMeas 78
NMEA 22, 29
npChStatusType 39, 60
npCompTimeType 40
npDgpsCorrType 40, 72
npDopType 41
npErrorEstType 41
npFixChType 41
npFixType 43
npNavConfigType 44
npNavFixType 45
pdblPosLLA 81
Position 18
Position accuracy 28
power supply 12
PPS output 21
ppucAddr 59
Program status 20
ptAllChStatus 60
ptCompTime 61
ptDgpsCorr 62, 72
ptFixSvSel 75
ptNavConfig 67, 73
ptNavFix 66
ptNavStatus 68
npNavStatusType 46
npOscStatusType 48, 54
npRetCode 58
npTempMeasType 48
npTimeStatusType 57
npVersionTagType 49
npVersionType 49
ptOscStatus 70
ptTempMeas 77
Num channels 27
pucCount 62
pulEvent 63, 65
pulSize 59
O
online Help x
Operating dimension 53
Oscillator offset 24
Oscillator status code 54
pvEventData 63, 65
pvTaskId 63, 65
PVT-serial solution 2
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Start GPS 20
STATUS_FREQ_LOCK 52
STATUS_FRESH_MEAS 52
STATUS_LOCK_POINT_KNOWN 52
STATUS_PHASE_LOCK 52
STATUS_RESET 52
R
reader comment form 93
readme.txt file x
Real-time Operating System 8
Receiver oscillator frequency offset
availability 46
Receiver status 18
Reference altitude 21
release notes x
Reset
STATUS_TIME_KNOWN 52
STATUS_VALID_MEAS 52
Stop GPS 21
cold 21
hot 21
warm 21
Return types 58
RF ASIC 3
tChStatus 39
Temperature 25
tErrorEst 43
S
Satellite data 19
Satellite status code 57
Satellite visibility 25
sCno 39, 41
SCODE_0SVS 57
SCODE_1SV 57
SCODE_2SVS 57
SCODE_3SVS 57
tFiltFix 45
SCODE_BAD_1SV 57
SCODE_DCORR_GEN 57
SCODE_DOING_FIXES 57
SCODE_GOOD_1SV 57
SCODE_NEED_TIME 57
SCODE_OVERDET_CLK 57
SCODE_PDOP_HIGH 57
sDatumIndex 45
tFixCh 45
Time function 17
tNpSwVer 49
tRawFix 45
tRtosVer 49
TTFF 27
Signal level output 23
Signal strength 19
Sky plots 22
Standard FirstGPS events 58
FirstGPS Starter Kit User Guide 91
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Index
ulMeasCount 48
ulMsecs 40
usGpsWeek 80
usGpsWn 71
usMeasStatus 39
usRefScount 40
usReserved 39
usWeeks 40
U
ucAlmStatus 47
ucAmu5 39, 41
ucBeta 49
ucClearFlag 72
ucCount 72
ucDay 49
ucDgpsAgeLlimit 44
ucDgpsCfg 44
ucDgpsFlag 45
ucDgpsMode 42
ucDimMode 42
ucDynamics 44
ucGetFlag 63, 65
ucHaveBias 48, 54
ucIod 40
usWeekTag 45
ucIode 41
ucLpFixRate 44
ucMajor 49
ucMemStatus 47
ucMinor 49
Visual position 22
ucMonth 49
ucNavStatus 39
ucNumSvsUsed 45
ucOprtngDim 44
ucOscStatus 47
ucPosStatus 47, 56
ucSatCnt 42
Warm resets 21
ucSource 45, 54
ucStatus 40, 42, 45, 55
ucSvId 39, 40
ucSvUsed 41
ucTimeStatus 47, 80
ulAlmHealthStatus 47
ulAlmPageStatus 47
ulEphStatus 47
ulGpgMsec 80
ulGpsTowMsec 39, 71
92 FirstGPS Starter Kit User Guide
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Reader Comment Form
FirstGPS Starter Kit User Guide
P/N: 44326-00-ENG
March 2001
Revision A
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