Sierra Wireless AirPrime XA1110 User manual

AirPrime XA1110/XM1110
AirPrime XA1110/XM1110
41111116
Rev 1

AirPrime XA1110/XM1110 Hardware Design Guide
Rev 1 Jun.17 2 41111116
Important
Notice
Due to the nature of wireless communications, transmission and reception of data
can never be guaranteed. Data may be delayed, corrupted (i.e., have errors) or be
totally lost. Although significant delays or losses of data are rare when wireless
devices such as the Sierra Wireless modem are used in a normal manner with a
well-constructed network, the Sierra Wireless modem should not be used in
situations where failure to transmit or receive data could result in damage of any
kind to the user or any other party, including but not limited to personal injury,
death, or loss of property. Sierra Wireless accepts no responsibility for damages
of any kind resulting from delays or errors in data transmitted or received using
the Sierra Wireless modem, or for failure of the Sierra Wireless modem to
transmit or receive such data.
Safety and
Hazards
Do not operate the Sierra Wireless modem in areas where blasting is in progress,
where explosive atmospheres may be present, near medical equipment, near life
support equipment, or any equipment which may be susceptible to any form of
radio interference. In such areas, the Sierra Wireless modem MUST BE
POWERED OFF. The Sierra Wireless modem can transmit signals that could
interfere with this equipment.
Do not operate the Sierra Wireless modem in any aircraft, whether the aircraft is
on the ground or in flight. In aircraft, the Sierra Wireless modem MUST BE
POWERED OFF. When operating, the Sierra Wireless modem can transmit
signals that could interfere with various onboard systems.
Note: Some airlines may permit the use of cellular phones while the aircraft is on the
ground and the door is open. Sierra Wireless modems may be used at this time.
The driver or operator of any vehicle should not operate the Sierra Wireless
modem while in control of a vehicle. Doing so will detract from the driver or
operator's control and operation of that vehicle. In some states and provinces,
operating such communications devices while in control of a vehicle is an offence.
Limitation of
Liability
The information in this manual is subject to change without notice and does not
represent a commitment on the part of Sierra Wireless. SIERRA WIRELESS AND
ITS AFFILIATES SPECIFICALLY DISCLAIM LIABILITY FOR ANY AND ALL
DIRECT, INDIRECT, SPECIAL, GENERAL, INCIDENTAL, CONSEQUENTIAL,
PUNITIVE OR EXEMPLARY DAMAGES INCLUDING, BUT NOT LIMITED TO,
LOSS OF PROFITS OR REVENUE OR ANTICIPATED PROFITS OR REVENUE
ARISING OUT OF THE USE OR INABILITY TO USE ANY SIERRA WIRELESS
PRODUCT, EVEN IF SIERRA WIRELESS AND/OR ITS AFFILIATES HAS BEEN
ADVISED OF THE POSSIBILITY OF SUCH DAMAGES OR THEY ARE
FORESEEABLE OR FOR CLAIMS BY ANY THIRD PARTY.
Notwithstanding the foregoing, in no event shall Sierra Wireless and/or its
affiliates aggregate liability arising under or in connection with the Sierra Wireless
product, regardless of the number of events, occurrences, or claims giving rise to
liability, be in excess of the price paid by the purchaser for the Sierra Wireless
product.

Preface
Rev 1 Jun.17 3 41111116
Patents This product may contain technology developed by or for Sierra Wireless Inc. This
product includes technology licensed from QUALCOMM®. This product is
manufactured or sold by Sierra Wireless Inc. or its affiliates under one or more
patents licensed from InterDigital Group and MMP Portfolio Licensing.
Copyright © 2017 Sierra Wireless. All rights reserved.
Trademarks Sierra Wireless®, AirPrime®, AirLink®, AirVantage®and the Sierra Wireless logo
are registered trademarks of Sierra Wireless.
Windows®and Windows Vista®are registered trademarks of Microsoft
Corporation.
Macintosh®and Mac OS X®are registered trademarks of Apple Inc., registered in
the U.S. and other countries.
QUALCOMM®is a registered trademark of QUALCOMM Incorporated. Used
under license.
Other trademarks are the property of their respective owners.
Contact
Information
Revision
History
Sales information and technical
support, including warranty and returns
Web: sierrawireless.com/company/contact-us/
Global toll-free number: 1-877-687-7795
6:00 am to 6:00 pm PST
Corporate and product information Web: sierrawireless.com
Revision
number
Release date Changes
1June 23, 2017 Initial draft in SWI template.

Rev 1 Jun.17 4 41111116
Contents
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6
Precautions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Technical Support. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
General Rules for Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9
Circuit Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Power Supply - Compatible Models: Gmm-g3, Gmm-g3(B), Gms-g6a, Gms-
g9, Gms-g6, Gms-b6,PA6E-CAM, XM1110, XA1110 . . . . . . . . . . . . . . . .9
VBACKUP backup battery - Compatible Models: Gmm-g3, Gmm-g3(B),
Gms-g6a, Gms-g9, Gms-g6, Gms-b6, PA6E-CAM, XM1110, XA1110 . .10
UART / I2C/ SPI Serial Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10
GND-Ground - Compatible Models: Compatible Models: Gmm-g3, Gmm-
g3(B), Gms-g6a, Gms-g9, Gms-g6, Gms-b6, PA6E-CAM, XM1110, XA1110 12
Antenna Compliance Design - Compatible Models: Gmm-g3, Gmm-g3(B),
XM1110, XA1110 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12
1PPS - Compatible Models: Gmm-g3, Gmm-g3(B), Gms-g6a, Gms-g9, Gms-
g6, Gms-b6,PA6E-CAM, XM1110, XA1110 . . . . . . . . . . . . . . . . . . . . . . .17
3D_Fix - Compatible Models: Gmm-g3, Gmm-g3(B), Gms-g6a, Gms-g9,
Gms-g6, Gms-b6 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .19
1.8V Boost to 3.3V Application. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Layout Guidelines. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Layout Underneath the GNSS Module - Compatible Models: Gmm-g3,
Gmm-g3(B), Gms-g6a, Gms-g9, Gms-g6, Gms-b6,PA6E-CAM, XM1110,
XA1110 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .22
Keep Far Away from High Profile or Metal-Canned Components - Compati-
ble Models: Gms-g6a, Gms-g9, Gms-g6, Gms-b6,PA6E-CAM, XA1110 25
Placement - Compatible Models: Gmm-g3, Gmm-g3(B), Gms-g6a, Gms-g9,
Gms-g6, Gms-b6, PA6E-CAM, XM1110, XA1110 . . . . . . . . . . . . . . . . . .26
Trace - Compatible Models: Gmm-g3, Gmm-g3(B), Gms-g6a, Gms-g9, Gms-
g6, Gms-b6,PA6E-CAM, XM1110, XA1110 . . . . . . . . . . . . . . . . . . . . . . .26
Ground Segmentation - Compatible Models: Gmm-g3, Gmm-g3(B), Gms-g6a,
Gms-g9, Gms-g6, Gms-b6, PA6E-CAM, XM1110, XA1110 . . . . . . . . . .27
Ground Plane - Compatible Models: Gms-g9,PA6E-CAM, Gms-g6, Gms-b6,
XA1110 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .27
Metal Effect on the GNSS Module Compatible Model: Gms-g6a. . . . . . . . . 29

Contents
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Thermal Profile for SMD Modules . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
SMT Reflow Soldering Temperature Profile . . . . . . . . . . . . . . . . . . . . . . . . 30
SMT Solder Mask . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
Manual Soldering. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
How to Check the Working Status of the GPS Module . . . . . . . . . . . . . . . . 31
Super Capacitor Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
About Super Capacitors. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
How to Calculate the Backup Time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
50 Ω Antenna Matching . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
UART to RS232 Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
UART to USB Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
How to Efficiently Transfer 1PPS Through Extended Distances . . . . . . . . 37
1pps Delay Time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
The Delay Time Caused by the Cable . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
Calculating the Delay Time in Respect to the Communication Cable Length 39
Waveform Rising Time Caused by OP-amp . . . . . . . . . . . . . . . . . . . . . . . . 40
Recommended OP-amp . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
Voltage degradation of Communication cable . . . . . . . . . . . . . . . . . . . . . . . 40
Reflow Soldering Precautions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
Other Cautionary Notes on the Reflow-Soldering Process . . . . . . . . . . . . . 43
Manual Soldering. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
Soldering Iron . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44

Rev 1 Jun.17 6
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1
1: Introduction
The purpose of this application note is to assist the system developer and integrator
with the MT3333 chip-based Sierra Wireless receiver modules during the process of
implementation. This document covers the following receiver modules:
Standard Modules
•XM1110
•Firefly 1 (Gmm-g3)
•Firefly 1b (Gmm-g3b)
Antenna Modules
•XA1110
•Titan 1 (PA6E-CAM)
•Titan 2 (Gms-g6)
•Titan 2B (Gms-b6)
•Titan 3 (Gms-g6)
•Stand Alone GPS module: FireFly 1 & FireFly 1b (Gmm-g3, Gmm-g3(B)) and
XM1110
Figure 1-1: Stand Alone GPS modules. Left: FireFly 1 & FireFly 1b (Gmm-g3, Gmm-g3(B)). Right: XM1110
•Built-in Chip Antenna Module: Carrion 2 (Gms-g6a)
Figure 1-2: Built-in Chip Antenna Module: Carrion 2 (Gms-g6a)
•Built-in Patch Antenna Modules: Titan 2 (Gms-g6) and Titan 2B (Gms-b6), Titan 3
(Gms-g9) and Titan1 (PA6E-CAM), and XA1110.

Introduction
Rev 1 Jun.17 7 41111116
Figure 1-3: Titan 2 (Gms-g6) and Titan 2B (Gms-b6)
Figure 1-4: Titan 3 (Gms-g9) and Titan1 (PA6E-CAM)
Figure 1-5: XA1110
Precautions
Please read carefully before you start
If you use the GNSS receiver inside buildings, tunnels, or beside any huge
objects, the GNSS signals might be cut-off or weakened. Please do not assume
the receiver has malfunctioned.
This application note provides the necessary guidelines for a successful system
design using GNSS modules. For detailed module specifications, please refer to
the corresponding datasheet of the GNSS module.
The GNSS module is an electrostatic sensitive device, please DO NOT touch the
GPS module directly. Follow ESD safety rules when handling.
When using the device for the first time, it is strongly recommended to test the
device outdoors with open sky for at least 10 to 15 minutes to ensure that full
ephemeris data received.

AirPrime XA1110/XM1110 Hardware Design Guide
Rev 1 Jun.17 8 41111116
Technical Support
If you have any technical problems or cannot find the required information in our
documents, please feel free to contact us for technical support. Below is a list of
information which you can provide to us to help us in determining the source of
the problem and the necessary solution:
1. Your company name and website.
2. Description about application and system.
3. GNSS module type.
4. GNSS firmware version.
5. Description of the question or problems encountered, together with figures,
pictures or videos files.
a. Test setup.
b. The problem or issue shown in figures.

Rev 1 Jun.17 9
41111116
2
2: General Rules for Design
This section provides some rules when using the GNSS module to obtain good GNSS
performance.
Circuit Design
Power Supply - Compatible Models: Gmm-g3,
Gmm-g3(B), Gms-g6a, Gms-g9, Gms-g6, Gms-
b6,PA6E-CAM, XM1110, XA1110
It is necessary to provide a clean and stable power supply for our GNSS module in
order to obtain good performance. An unstable power source will have a significant
negative impact on the performance. To achieve high-quality performance, the VCC
ripple must be controlled under 50mVpp. In addition, there are also some important
suggestions for main power circuit design:
1. Add a ferrite bead, power choke, or low pass filter for power noise reduction.
2. A linear regulator (LDO) is better than a switch DC/DC power supplier in the
ripple.
3. Use enough decoupling capacitors beside the VCC for stable voltage.
Figure 2-1: Power Design for the GNSS Module

AirPrime XA1110/XM1110 Hardware Design Guide
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VBACKUP backup battery - Compatible
Models: Gmm-g3, Gmm-g3(B), Gms-g6a, Gms-
g9, Gms-g6, Gms-b6, PA6E-CAM, XM1110,
XA1110
The GNSS module has a built-in charging circuit which charges the rechargeable
coin battery.
For most systems, it is recommended to provide the module with backup power
(e.g. Li-Ion rechargeable coin battery, super capacitor). See Figure 2-2 for a
reference design.
For information on the super capacitor reference design, please refer to Super
Capacitor Design.
Backup power is useful in order to maintain RTC operation and retain Ephemeris
data in flash memory which can get a faster TTFF and acquire PVT (Position,
Velocity, Time) information.
If VBACKUP isn’t connected to any coin battery, the GNSS module will execute a
cold start whenever the system is restarted.
Figure 2-2: Built-in a charging circuit for GNSS module
UART / I2C/ SPI Serial Interface
UART 0 (RX/TX) Compatible Models: Gmm-g3, Gmm-
g3(B), Gms-g6a, Gms-g9, Gms-g6, Gms-b6,PA6E-
CAM, XM1110, XA1110
1. UART is the TTL level interface that carries the baud rate ranging from 4800
bps to 115200 bps.
2. Placing a damping resistor on the RX and TX of the GNSS module could limit
the interference from the host MCU or high speed digital logics. Fine tuning
the damping resistor is required to efficiently suppress interference. The
damping resistor is a wire wound component and may function as a choke
coil.

General Rules for Design
Rev 1 Jun.17 11 41111116
3. Please don’t connect diode(s) to RX/TX as it will decrease the signal driving
capability which might adversely affect the RX/TX signal level. In some cases
no data output will occur.
4. If RS232 logic-level is needed for any particular application, the level shifter
will be necessary. For more information please refer to UART to RS232
Interface.
5. If USB logic-level is needed for any particular application please refer to
UART to USB Interface.
I2C (SCL/SDA) - Compatible Models: XM1110, XA1110
1. The I2C interface is mainly connected to external devices. MT3333 supports
only slave mode (default slave address is 0x10). MT3333 has 256 bytes
URAM mode and 8-byte FIFO mode for transmitting and receiving data. The
bit rate is up to 400 kb/s for fast mode. In addition, MT3333 supports manual
or automatic indicator for data transfer in the slave mode. Device addresses
in the slave mode are programmable.
2. Pull-up resistor must be added for I2C bus:
Figure 2-3: Addition of Pull-up Resistor
SPI (CS/CLK/MISO/MOSI) - Compatible Model: Gmm-
3301, XA1110
1. The serial peripheral interface port manages the communication between the
digital BB and external devices. The MT3333 supports only slave mode. The
slave has a 4 byte-register mode or URAM mode. In URAM mode, the trans-
mitted and received data size is 256 bytes. The clock phase and clock polarity
are selectable. The MT3333 supports a manual or automatic indicator for
data transfer in slave mode. The bit rate is up to 700kb/s.

AirPrime XA1110/XM1110 Hardware Design Guide
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GND-Ground - Compatible Models: Compatible
Models: Gmm-g3, Gmm-g3(B), Gms-g6a, Gms-
g9, Gms-g6, Gms-b6, PA6E-CAM, XM1110,
XA1110
Make sure all GND pins of the module are connected to a completed ground
plane.
The separation of ground between the GNSS module and the rest of the system
are recommended to avoid interference. If this setup is not possible, it is best to
follow these rules: divide the segmentation of the ground between the digital and
analogue system, high current and low current system, and different radiation
systems in general (such as GNSS and GPRS).
One method to segment the ground is to place digital and noise components at
one corner of the board, while placing analog and quiet components at the
opposite corner of the board. Make sure there is no crossing of microstrip or
current between the two component sets with the ground of each set to be
connected to one point only.
Another method is to place the two different sets at different layers of the board
while the ground of each layer is connected to one point only which is preferably
located at the border of the board practically.
Antenna Compliance Design - Compatible
Models: Gmm-g3, Gmm-g3(B), XM1110, XA1110
The GNSS antenna is a receiving part of the device to acquire weak GNSS
signals from the sky. A common solution would be to use a ceramic patch
antenna because of its small form factor and low cost. There are two types of
antennas: passive and active.
A passive antenna, like a patch antenna and chip antenna, is solely by itself
without signal amplifier such as LNA. It must be fine tuned for the specific module
model to obtain the best signal receiving performance.
An external antenna is a standalone device, which integrates an LNA and patch
antenna with an RF cable for higher gain. This performs better than a passive
antenna.
The antenna can be chosen according to the radiation efficiency, radiation
pattern, gain, bandwidth, form factor, and cost. Make sure the ground plane is
sufficient for the antenna to ensure better performance.
Design Patch Antenna with GNSS module.
1. In general, a 50Ω patch antenna will work well with the GNSS module. The
antenna can be connected to the Antenna IN pin with a 50Ω impedance
trace.
2. Please keep the patch antenna far away from noise sources such as the
switching power supply and high speed digital logic and radar wave guide.

General Rules for Design
Rev 1 Jun.17 13 41111116
3. The 50Ω trace should be kept as short as possible to reduce the chance of
picking up noise from the air and PCB. A simple direct-line trace is recom-
mended.
4. If needed, a matching circuit could be placed between the patch antenna and
the GNSS module. The matching circuit design should be discussed with the
module and patch antenna manufacturer.
5. For 50Ω matching, please refer to 50 Ω Antenna Matching.
Figure 2-4: PCB trace design for antenna impedance matching
Selecting an External Antennal Architecture for the
GNSS Module
An external antenna requires DC power in order to work properly. A typical
method is to feed DC into the RF trace. The external antenna then extracts the
DC from the RF trace. Thus the RF trace transports both the RF signal and DC
power. An RF chock coil couples the DC power to the RF trace to perform this
method.
The Sierra Wireless modules provide a circuit for connecting an external antenna
and power feeding method as depicted in Figure 2-5, Figure 2-6, and Figure 2-7
below. Please select the module prudently while applying the design with an
external antenna.
•Mode1 (i.e. Gmm-g3, Gmm-g3(B)): the power supply for the external
antenna needs to be externally fed into the module via the VANT pin and the
antenna connected to the Antenna IN pin:
Figure 2-5: Mode 1: (Internal chock coil)

AirPrime XA1110/XM1110 Hardware Design Guide
Rev 1 Jun.17 14 41111116
•Mode2 (i.e. XM1110): The power supply needs to be externally provided and
is connected directly to the external antenna via a chock coil.
Note: Chock Coil for reference: LQG15HS33NJ02D (Murata)
Figure 2-6: Mode 2: (External chock coil)
Note: Chock Coil for reference: LQG15HS33NJ02D (Murata)
•Mode3 (i.e. PA6E-CAM, XA1110): The power supply for the external antenna
needs to be externally fed into the module from the VCC pin directly and
connect antenna to EX_ANT pin.
Figure 2-7: Mode 3: (Internal chock coil)

General Rules for Design
Rev 1 Jun.17 15 41111116
Figure 2-8: Modes
Design chip antenna with GNSS module
Different vendors have different reference designs, so we list two chip antenna
sources: Pulse and Unictron.
1. Antenna source: Pulse
Figure 2-9: Pulse Schematic Design
Figure 2-10: Pulse PCB Layout
When selecting the Antenna source, check its datasheet first before tuning an RF
match component’s footprint (such as: C27, C28). You can base this on its PCB
size and housing to tune for an optimal value and meet the GNSS’s frequency in
order to get a good reception effect.

AirPrime XA1110/XM1110 Hardware Design Guide
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Pulse web site:
www.pulseeng.com/antennas
Note: C27, C28’s value are still based on your actual trace to tune it.
2. Antenna source: Unictron
Figure 2-11: Unictron Schematic
Figure 2-12: Unictron PCB
When you select this source, check its datasheet first before tuning the RF match
component’s footprint (such as: C26, C27, C28, C29, C30). You can tune based
on the PCB size and housing to tune for an optimal value in order to meet the
GNSS’s frequency and obtain good reception.
Unictron web site:
http://www.unictron.com/index/
Note: C26,C27,C28,C29,C30’s value are still based on your actual trace to tune it.

General Rules for Design
Rev 1 Jun.17 17 41111116
External Antenna of Specification
When select your external antenna, refer to the specification shown in Table 2-1
and Table 2-2 below.
The Gmm-g3 module uses the GPS/GLONASS External Antenna:
The Gmm-g3(B) module uses the Beidou/GPS External Antenna:
1PPS - Compatible Models: Gmm-g3, Gmm-
g3(B), Gms-g6a, Gms-g9, Gms-g6, Gms-
b6,PA6E-CAM, XM1110, XA1110
1PPS signal is an output pulse signal used for timing applications. Its electrical
characteristics are:
•Low Voltage level: 0~0.4V
•High Voltage level: 2.8~3.1V
Table 2-1: GPS/GLONASS External Antenna
Characteristic Specification
Polarization Right-hand circular polarized
Frequency Received 1.575GHz~1.615GHz
Power Supply 3.3V
DC Current 5mA<IDC<11mA at 3.3V
Total Gain 27±3dB
Output VSWR 2.0
Impendence 50Ω
Noise Figure 2dB
Table 2-2: Beidou/GPS External Antenna
Characteristic Specification
Polarization Right-hand circular polarized
Frequency Received 1.561GHz~1.575GHz
Power Supply 3.3V
DC Current 3mA<IDC<30mA at 3.3V
Total Gain 27±1dB
Output VSWR 2.0
Impendence 50Ω
Noise Figure 1.5dB

AirPrime XA1110/XM1110 Hardware Design Guide
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•Period: 1s
•Accuracy (jitter):±20ns
•100ms pulse width duration (firmware customization for pulse width duration
is available)
Figure 2-13: 1PPS signal and its pulse width with 100ms duration
Free run 1PPS Output Before 3D_FIX
The Sierra Wireless standard GNSS module outputs 1PPS signal after the
module obtains a 3D_FIX. This is a factory default setting.
Cable Delay Compensation
In some cases a long distance connection (~300m) may be needed. For a timing
application, the cable length is critical. For more information on 1PPS signal
transmission delay please refer to How to Efficiently Transfer 1PPS Through
Extended Distances.
LED Indicator for 1PPS Signal
For 1PPS LED indication, you may connect an LED indicator with a 330ohm
resistor in series.

General Rules for Design
Rev 1 Jun.17 19 41111116
Figure 2-14: 1PPS Signal Design for IO
3D_Fix - Compatible Models: Gmm-g3, Gmm-
g3(B), Gms-g6a, Gms-g9, Gms-g6, Gms-b6
3D_Fix signal is an output pulse signal used for GPS fix applications. Its electrical
characteristics are:
•Low Voltage level: 0~0.4V
•High Voltage level: 2.8~3.1V
•Source current (Max.): 14mA, sink current 14mA
Signal Output Before 2D Fix:
Duration: 1 second high and 1 second low.
Period: 2s
(Firmware customizable)
Figure 2-15: Signal Output Before 2D Fix

AirPrime XA1110/XM1110 Hardware Design Guide
Rev 1 Jun.17 20 41111116
Signal Output After 2D or 3D Fix
Duration: Constant low level output
(Firmware customizable)
Figure 2-16: Signal output after 2D or 3D Fix
For 3D_Fix indication, you may connect an LED with a 330ohm resister in series
in two ways as shown in Figure 2-17 and Figure 2-18.
Figure 2-17: 3D_Fix signal design for IO (LED ON when high, LED OFF when low)
Figure 2-18: 3D_Fix signal design for IO (LED ON when low, LED OFF when high)