Telit Wireless Solutions SE873Q5, SE873 Series, SE868-V3 Product User Manual
SE873 Family
Product User Gui de
1VV0301216 Rev. 4
2018-08-24
SE873 Family Product User Guide Notices
SPECIFICATIONS ARE SUBJECT TO CHANGE WITHOUT NOTICE
NOTICES
While reasonable efforts have been made to assure the accu racy of this document, Telit assumes
no liability resulting from any inaccuracies or omissions in this document, or from use of the
information obtained herein. The information in this document has been carefully checked and is
believed to be reliable. However, no responsibility is assumed for inaccuracies or omissions. Telit
reserves the right to make changes to any products described herein and reserves the right to
revise this document and to make changes from time to time in content hereof with no obligation
to notify any person of revisions or changes. Telit does not assume any liability arising out of the
application or use of any product, software, or circuit described herein; neither does it convey
license under its patent rights or the rights of others.
It is possible that this publication may contain references to, or information about Telit products
(machines and programs), programming, or services that are not announced in your country.
Such references or information must not be construed to mean that Telit intends to announce
such Telit products, programming, or services in your country.
COPYRIGHTS
This manual and the Telit products described in it may be, include or describe copyrighted Telit
material, such as computer programs stored in semiconductor me mories or other media. Laws in
Italy and other countries preserve for Telit and its licensors cer tain exclusive rights for copyrighted
material, including the exclusive right to copy, reproduce in any form, distribute, and make
derivative works of the copyrighted material. Accordingly, any copyrighted material of Telit and its
licensors contained herein or in the Telit products described in this manual may not be copied,
reproduced, distributed, merged, or modified in any manner without the express written
permission of Telit. Furthermore, the purchase of Telit products shall not be deemed to grant
either directly or by implication, estoppel, or otherwise, any license under the copyrights, patents,
or patent applications of Telit, as arises by operation of law in the sale of a product.
COMPUTER SOFTWARE COPYRIGHTS
The Telit and 3rd Party supplied Software (SW) products described in this manual may include
copyrighted Telit and other 3rd Party supplied computer programs stored in semiconductor
memories or other media. Laws in Italy and other countries preserve for Telit and other 3rd Party
supplied SW certain exclusive rights for copyrighted computer programs, including the exclusive
right to copy or reproduce in any form the copyrighted computer program. Accordingly, any
copyrighted Telit or other 3rd Party supplied SW computer programs contained in the Telit
products described in this instruction manual may not be copied (reverse engineered) or
reproduced in any manner without the express written permission of Telit or the 3rd Pa rty SW
supplier. Furthermore, the purchase of Telit products shall not be deemed to grant either directly
or by implication, estoppel, or otherwise, any license under the copyrights, patents, or patent
applications of Telit or other 3rd Party supplied SW, except for the normal non-exclusive, royalty
free license to use that arises by operation of law in the sale of a product.
1VV0301216 Rev.4 Page 2 of 69 2018-08-24
SE873 Family Product User Guide Notices
Usage and Disclosure Re str ic t ions
I. License Agreements
The software described in this document is the property of Telit and its licensors. It is furnished
by express license agreement only and may be used only in accordance with the terms of such
an agreement.
II. Copyrighted Materials
Software and documentation are copyrighted materials. Making unautho rized copies is prohibited
by law. No part of the software or documentation may be reproduced, transmitted, transcribed,
stored in a retrieval system, or translated into any language or computer language, in any form or
by any means, without prior written permission of Telit
III. High Risk Materials
Components, units, or third-party products used in the product described herein are NOT faulttolerant and are NOT designed, manufactured, or intended for use as on-line control equipment
in the following hazardous environments requiring fail-safe controls: the operation of Nuclear
Facilities, Aircraft Navigation or Aircraft Communication Systems, Air Traffic Control, Life Support,
or Weapons Systems (High Risk Activities"). Telit and its supplier(s) specifically disclaim any
expressed or implied warranty of fitness for such High-Risk Activities.
IV. Trademarks
TELIT and the Stylized T Logo are registered in Trademark Office. All other product or service
names are the property of their respective owners.
V. Third Party Right s
The software may include Third Party Right software. In this case you agree to comply with all
terms and conditions imposed on you in respect of such separate software. In addition to Third
Party Terms, the disclaimer of warranty and limitation of liability provisions in this License shall
apply to the Third-Party Right software.
TELIT HEREBY DISCLAIMS ANY AND ALL WARRANTIES EXPRESS OR IMPLIED FROM ANY
THIRD PARTIES REGARDING ANY SEPARATE FILES, ANY THIRD PARTY MATERIALS
INCLUDED IN THE SOFTWARE, ANY THIRD PARTY MATERIALS FROM WHICH THE
SOFTWARE IS DERIVED (COLLECTIVELY “OTHER CODE”), AND THE USE OF ANY OR ALL
THE OTHER CODE IN CONNECTION WITH THE SOFTWARE, INCLUDING (WITHOUT
LIMITATION) ANY WARRANTIES OF SATISFACTORY QUALITY OR FITNESS FOR A
PARTICULAR PURPOSE.
NO THIRD PARTY LICENSORS OF OTHER CODE SHALL HAVE ANY LIABILITY FOR ANY
DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
DAMAGES (INCLUDING WITHOUT LIMITATIO N LOST PROFIT S), HOWEVER CAUSED AND
WHETHER MADE UNDER CONTRACT, TORT OR OTHER LEGAL THEORY, ARISING IN ANY
WAY OUT OF THE USE OR DISTRIBUTION OF T HE OTHER CODE OR T HE EXERCISE OF
ANY RIGHTS GRANTED UNDER EITHER OR BOTH THIS LICENSE AND THE LEGAL TERMS
APPLICABLE TO ANY SEPARATE FILES, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
DAMAGES.
1VV0301216 Rev.4 Page 3 of 69 2018-08-24
SE873 Family Product User Guide Product Applicability Table
PRODUCT
SE873
SE873Q5
PRODUCT APPLICABILITY TABLE
Table 0-1 Product Applicability Table
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SE873 Family Product User Guide Contents
CONTENTS
NOTICES .................................................................................................................................... 2
PRODUCT APPLICABILITY TABLE .......................................................................................... 4
CONTENTS ................................................................................................................................ 5
1. INTRODUCTION ............................................................................................................. 11
Purpose ...................................................................................................................... 11
Contact and Support Information ................................................................................. 11
Related Documents and Downloads ........................................................................... 11
Related Documents Requiring a Non-Disclosure Agreement 11
Text Conventions ........................................................................................................ 12
2. PRODUCT DESCRIPTION .............................................................................................. 13
Product Overview ........................................................................................................ 13
Product Variants.......................................................................................................... 13
Block Diagram ............................................................................................................. 14
SE873 Modules Photos ............................................................................................... 15
3. SE873 EVALUATON KIT (EVK) ..................................................................................... 16
SE873 Evaluation Unit ................................................................................................ 17
4. PRODUCT FEATURES ................................................................................................... 18
Multi-Constellation Navigation ..................................................................................... 18
Quasi-Zenith Satellite System (QZSS) support ........................................................... 18
Satellite Based Augmentation System (SBAS) ............................................................ 18
SBAS Corrections 18
SBAS Ranging 18
Assisted GPS (AGPS) - SiRFInstantFix™ ................................................................... 18
Client-generated Extended Ephemeris (CGEE) 19
Server-generated Extended Ephemeris (SGEE) 19
2-D Positioning ............................................................................................................ 19
Static Navigation ......................................................................................................... 19
Velocity Dead-Reckoning ............................................................................................ 19
Jamming Rejection – Continuous Wave (CW) Jamming Mitigation ............................. 20
Elevation Mask Angle .................................................................................................. 20
5 Hz and 10 Hz Navigation .......................................................................................... 20
1PPS ........................................................................................................................... 20
Internal LNA ................................................................................................................ 21
Passive antenna: 21
Active antenna (or External LNA) with High Gain firmware: 21
Active antenna (or External LNA) with Low Gain firmware: 21
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SE873 Family Product User Guide Contents
Serial I/O Ports ............................................................................................................ 21
Power Management .................................................................................................... 22
Full Power Mode (default) 22
SmartGNSS 22
Trickle Power 23
Push-to-Fix 23
SiRFaware 23
Hibernate 23
5. PRODUCT PERFORMANCE .......................................................................................... 24
Horizontal Position Accuracy ....................................................................................... 24
Time to First Fix .......................................................................................................... 24
Sensitivity .................................................................................................................... 25
6. MESSAGE INTERFACE ................................................................................................. 26
NMEA Output Messages ............................................................................................. 26
Standard Messages 26
Proprietary Messages 27
NMEA Input Commands .............................................................................................. 27
Change output sentences and their rates 27
Change data rate 27
Switch to OSP protocol 27
OSP Output Messages................................................................................................ 28
OSP Input Commands ................................................................................................ 28
Change output messages 28
Change data rate 28
Switch to NMEA protocol and data rate 28
7. FLASH UPGRADABILITY .............................................................................................. 29
8. ELECTRICAL INTERFACE ............................................................................................. 30
Module Pin-out ............................................................................................................ 30
DC Characteristics 32
Absolute Maximum Ratings 32
Power Supply .............................................................................................................. 33
1.8 V Supply Voltage 33
DC Power Requirements 33
Power Supply Capacitance 33
DC Power Consumption 34
Control (input) SIgnals................................................................................................. 36
ON-OFF (input) and SYSTEM-ON (output) 36
nReset 36
Boot Select 37
Status (output) Signals ................................................................................................ 37
SYSTEM-ON 37
GNSS_ON (GPIO8) 37
1PPS 37
Serial I/O Ports - Configuration and Operation ............................................................ 38
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SE873 Family Product User Guide Contents
Primary Serial Port Configuration 38
Secondary Serial Port Configuration 38
UART Operation 39
I2C Operation 40
SPI Operation 40
RF Interface ................................................................................................................ 41
RF Input 41
External Active Antenna Voltage 41
Burnout Protection 41
Jamming Rejection 41
Frequency Plan 41
Local Oscillator Leakage 41
9. RF SIGNALS ................................................................................................................... 42
RF Input ...................................................................................................................... 42
GNSS Antenna Polarization ........................................................................................ 43
Active versus Passive Antenna ................................................................................... 43
GNSS Antenna Gain ................................................................................................... 43
System Noise Floor ..................................................................................................... 44
PCB stack and Trace Impedance ................................................................................ 44
RF Trace Losses ......................................................................................................... 45
Implications of the Pre-Select SAW Filter .................................................................... 45
RF Interference ........................................................................................................... 45
Shielding ..................................................................................................................... 46
Powering an External LNA .......................................................................................... 46
10. REFERENCE DESIGNS .................................................................................................. 47
11. MECHANICAL DRAWING .............................................................................................. 50
12. PCB FOOTPRINT ........................................................................................................... 51
13. PRODUCT PACKAGING AND HANDLING .................................................................... 52
Product Marking and Serialization ............................................................................... 52
Product Label – SE873 Family 52
Product Packaging and Delivery ................................................................................. 53
Moisture Sensitivity ..................................................................................................... 55
ESD Sensitivity ........................................................................................................... 57
Reflow ......................................................................................................................... 57
Assembly Considerations ............................................................................................ 57
Washing Considerations ............................................................................................. 57
Safety .......................................................................................................................... 57
Disposal ...................................................................................................................... 57
14. ENVIRONMENTAL REQUIREMENTS ............................................................................ 58
Operating Environmental Limits .................................................................................. 58
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SE873 Family Product User Guide Contents
Storage Environmental Limits ...................................................................................... 58
15. COMPLIANCES .............................................................................................................. 59
EU RED Certification ................................................................................................... 59
eCall Compliance ........................................................................................................ 59
GOST R-55534 Certification ....................................................................................... 59
EU RED Declarations of Conformity ............................................................................ 60
16. GLOSSARY AND ACRONYMS ...................................................................................... 62
17. SAFETY RECOMMENDATIONS..................................................................................... 66
READ CAREFULLY .................................................................................................... 66
Electrical and Fire Safety ............................................................................................ 67
18. DOCUMENT HISTORY ................................................................................................... 68
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SE873 Family Product User Guide Contents
FIGURES
Figure 2-1 SE873 Block Diagram ..............................................................................................14
Figure 2-2 SE873 module photo ...............................................................................................15
Figure 2-3 SE873Q5 module photo ...........................................................................................15
Figure 3-1 Evaluation Kit (EVK) contents ..................................................................................16
Figure 3-2 SE873 Evaluation unit ..............................................................................................17
Figure 8-1 SE873 Pin-out Diagram ...........................................................................................30
Figure 9-1 RF Trace Examples .................................................................................................45
Figure 10-1 SE873 Reference Design – Passive Antenna ........................................................47
Figure 10-2 SE873 Reference Design – Active Antenna ...........................................................48
Figure 11-1 SE873 Family Mechanical Drawing ........................................................................50
Figure 12-1 SE873 Family PCB Footprint .................................................................................51
Figure 13-1 SE873Q5 Product Label ........................................................................................52
Figure 13-2 Product Packaging - Tape and Reel 1500 pcs .......................................................53
Figure 13-3 Product Packaging - Tape and Reel 450 pcs .........................................................54
Figure 13-4 Moisture Sensitive Device Label ............................................................................56
Figure 15-1 EU RED Declaration of Conformity – SE873 ..........................................................60
Figure 15-2 EU RED Declaration of Conformity – SE873Q5 .....................................................61
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SE873 Family Product User Guide Contents
TABLES
Table 0-1 Product Applicability Table ......................................................................................... 4
Table 4-1 Internal gain value and external gain range ...............................................................21
Table 4-2 Power Management Modes ......................................................................................22
Table 5-1 SE873 Family - Horizontal Position Accuracy ............................................................24
Table 5-2 SE873 Family - Time to First Fix ..............................................................................24
Table 5-3 SE873 Family - Sensitivity ........................................................................................25
Table 6-1 Default NMEA Output Messages ...............................................................................26
Table 6-2 Available NMEA Output Messages ...........................................................................26
Table 6-3 NMEA Talker IDs ......................................................................................................27
Table 8-1 SE873 Pin-out Function Table...................................................................................31
Table 8-2 DC Characteristics ....................................................................................................32
Table 8-3 Absolute Maximum Ratings .......................................................................................32
Table 8-4 DC Supply Voltage ....................................................................................................33
Table 8-5 Power Consumption – SE873 ...................................................................................34
Table 8-6 Power Consumption – SE873 Low Power modes .....................................................34
Table 8-7 Power Consumption – SE873Q5 ...............................................................................35
Table 8-8 Power Consumption – SE873Q5 Low Power modes .................................................35
Table 8-9 Primary Serial Port Configuration ..............................................................................38
Table 8-10 UART Pin Assignments ...........................................................................................39
Table 8-11 I2C Pin Assignments ...............................................................................................40
Table 8-12 SPI Mode Pin Assignments .....................................................................................40
Table 8-13 Frequency Plan .......................................................................................................41
Table 8-14 LO Leakage ............................................................................................................41
Table 9-1 Inductor Loss ............................................................................................................46
Table 13-1 SE873Q5 Product Label Description .......................................................................52
Table 14-1 Operating Environmental Limits ..............................................................................58
Table 14-2 Storage Environmental Limits ..................................................................................58
1VV0301216 Rev.4 Page 10 of 69 2018-08-24
SE873 Family Product User Guide Introduction
1. INTRODUCTION
Purpose
The purpose of this document is to provide information regarding the function, features, and usage
of the Telit products listed in Table 0-1 Product Applicability Table.
Please refer to section 2 Product Description for details of the members of the product family.
Contact and Support Information
For general contact, technical support services, technical questions and report documentation errors
contact Telit Technical Support at:
• TS-EMEA@telit.com
• TS-AMERICAS@telit.com
• TS-APAC@telit.com
For detailed information about where you can buy the Telit modules or for recommendations on
accessories and components visit:
http://www.telit.com
Our aim is to make this guide as helpful as possible. Keep us informed of your comments and
suggestions for improvements.
Telit appreciates feedback from the users of our information.
Related Docum ents and Downloads
Please refer to http://www.telit.com/gnss/ for current documentation and downloads
• SE873 Data Sheet
• SE873 Evaluation Kit User Guide (1VV0301214)
Related Documents Requiring a Non-Disclosure Agreement
• SiRFstar V B02 Designer’s Guid e (CS -319281-AN-2)
• SiRFstar V B02 Software User's Guide (CS-314345-UG-2)
• NMEA Reference Guide (CS-129435-MA8)
• SiRFstar V One Socket Protocol Interface Control Document (CS-129291-DCP15)
• SiRFstar V OSP Extensions (CS-303979-7)
• Product firmware
1VV0301216 Rev.4 Page 11 of 69 2018-08-24
SE873 Family Product User Guide Introduction
Symbol
Description
Text Conventions
Dates are in ISO 8601 format, i.e. YYYY-MM-DD.
Danger – This in formation MUST be followed or catastrophic equipment
failure and/or bodily injury may occur.
Caution or Warning – This is an important point about integrating the
product into a system. If this information is disregarded, the product or
system may malfunction or fail.
Tip – This is advice or suggestion that may be useful when integrating
the product.
1VV0301216 Rev.4 Page 12 of 69 2018-08-24
SE873 Family Product User Guide Product Description
2. PROD UCT DES CRIPTI ON
The SE873 modules are complete multi-constellation position, velocity, and time (PVT) engines
featuring high performance, high sensitivity, and low power consumption, w hich are based on the
SiRFstar 5e (B02) flash GNSS chip. These modules are capable of excellent performance in
harsh environments. The inclusion of the GLONASS and BeiDou constellations yields better
coverage, greater accuracy, and improved availability.
Special Features
Very small form factor: 7 x 7 x 1.85 mm
Product Overvi ew
• Com plete GNSS receiver module including memory, LNA, TCXO, and RTC
• Based on the SiRFstar 5e (B02) flash GNSS chip
• Constellations: GPS, Galileo, QZSS, and either Glonass or BeiDou
• SBAS c ap able (WAAS, EGNOS, MSAS, GAGAN), including ranging
• AG PS support for extended ephemeris using local or server-based solutions:
o Client-Generated Extended Ephemeris (CGEE)
o Server-Generated Extended Ephemeris (SGEE)
• Jam ming Rejection
• Multipath mitigation
• Supports passive or active antenna
• 1PPS output
• Power management modes for extended battery life
o SiRFSmartGNSS I, SiRFSmartGNSS II
o Push-to-Fix, Trickle Power, SiRFaware
• Fix reporting at 1 H z, 5 Hz, or 10 Hz
• Command input and data output
o NMEA-0183
o OSP (binary)
• Two serial ports
o Primary serial port: configurable for UART, I
o Secondary serial port: configurable for UART or I
• 16 Megabit built-in flash memory
• Less t han 70 mW total power consumption (SE873Q5 Full Power mode - typical)
• Suppor t ed by evaluation kits
• -40°C to +85°C industrial temperature range
• 7. 0 x 7.0 x 1.85 mm (nominal) 20-pad QFN package
• Surface mountable by standard SMT equipment
• eCall and ERA/GLONASS compliant
• RoHS and RED compliant design
2
C, or SPI interface
2
C interface
Product Variants
The SE873 family has the following members:
• SE873: Linear power supply
• SE873Q5: Switching mode power supply
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SE873 Family Product User Guide Product Description
Block Diagram
Figure 2-1 SE873 Block Diagram
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SE873 Family Product User Guide Product Description
SE873 Modules Photos
Figure 2-2 SE873 module photo
Figure 2-3 SE873Q5 module photo
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SE873 Family Product User Guide SE873 Evaluaton Kit (EVK)
3. SE873 EVALUATON KIT (EVK)
Figure 3-1 Evaluation Kit (EVK) contents
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SE873 Family Product User Guide SE873 Evaluaton Kit (EVK)
SE873 Evaluation Unit
Figure 3-2 SE873 Evaluation unit
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SE873 Family Product User Guide Product Features
4. PROD UCT FE ATURES
Multi-Constellation Navigat ion
GPS and GLONASS constellations are enabled by default. GLONASS and BeiDou cannot both
be enabled at the same time. GPS, Galileo, GLONASS, and/or BDS constellations are
enable/disabled via OSP command MID 222,16..
Quasi-Zenith Satellite System (QZSS) support
The satellites of the Japanese regional system are in a highly inclined, elliptical geosynchronous
orbit, allowing continuous high-elevation coverage over Japan and other countries using only
three satellites plus one geostationary satellite. They provide additional ranging signals to
augment the GNSS systems along with a corrections data stream.
QZSS ranging is enabled by default, but can be disabled via OSP command MID 222,16.
Satellite Based Augmentation System (SBAS)
The receiver is capable of using SBAS satellites both as a source of differential corrections and
satellite ranging measurements. These systems (WAAS, EGNOS, GAGAN and MSAS) use
geostationary satellites to transmit regional corrections via a GNSS-compatible signal.
SBAS Corrections
The SBAS satellites transmit a set of differential corrections to their respective regions. The use
of SBAS corrections can improve positioning accuracy. However, the nav solution cannot use
mixed corrected and uncorrected satellites.
SBAS corrections are disabled by default but can be enabled via OSP MIDs 133, 138, and 170
commands. Thereafter, the receiver will demodulate and use corrections data from the SBAS
signal for satellites over 36 dB-Hz.signal level.
SBAS Ranging
The use of SBAS satellites can augment the number of measurements available for the navigation
solution, thus improving availability and accuracy.
SBAS satellite ranging is disabled by default but can be enabled via a NMEA $PSRF103
command or OSP Mode Control command MID 136 .
Assisted GPS (AGPS) - SiRFInstantFix™
A GNSS receiver requires ephemeris data to calculate the precise position in space of each
satellite to be used in the navigation solution. Since the satellites move at a speed of 3874 km/s
along their orbits and are subject to gravitational perturbations from all masses in the solar system,
this data must be both current and accurate. Each GPS satellite transmits a complete set of its
ephemeris coefficients (called the broadcast ephemeris or BE) every 30 seconds. This is
therefore the minimum time required for a cold start Time to First Fix (TTFF). The BE data is
usually refreshed every 2 hours.
The minimum cold start TTFF can be reduced from 30 seconds to just a few seconds by
implementing AGPS, which can provide Extended Ephemeris (EE) data by two methods -
1. Locally-generated (CGEE): The receiver includes software to project the future positions of the
satellites. This data may be calculated out to 14 days or even longer, depending on the
resources available in the receiver, e.g. computation ability and memory.
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SE873 Family Product User Guide Product Features
2. Server-generated (SGEE): A server calculates the future position projections and ma kes them
available to a receiver, typically over the internet. This data may be good for 30 days,
depending on available resources, e.g. communication links and storage.
Both CGEE and SGEE are available for GPS and GLONASS satellites.
Client-generated Extended Ephemeris (CGEE)
Extended ephemeris is computed in the receiver and then stored locally in the flash memory.
Whenever the module receives ephemeris data for a satellite, it checks if it has computed CGEE
for that satellite recently. If it has not, it computes EE for that satellite (for the nex t 3 days for GPS
and 1 day for GLONASS) and stores it in flash memory. The next time the module turns on and
broadcast ephemeris is not available for a visible satellite, the stored CGEE data is s earc hed t o
see if it is still valid and can be used. If EE data is av ailable for enough satellites, the receiver can
obtain a first fix in a few seconds rather than the usual 30+ seconds without EE data. CGEE is
enabled by default.
Server-generated Extended Ephemeris (SGEE)
Extended ephemeris is computed at the server and saved in a file which can then be downloaded
to the receiver’s flash memory. The server file contains 1, 3, 7, and 14, days of ephemerides. To
use SGEE data, a file must be transferred using NMEA or OSP commands. Please contact Telit
support for subscription details.
2-D Positioning
By default, the module will compute a 2-D solution if possible when performing initial acquisition.
In a 2-D solution, the receiver assumes a value for altitude and uses it to estimate the nav solution.
Under warm and hot start conditions, the receiver uses the last known value of altitude, which is
a good assumption in most situations. However, under cold start conditions, the last position is
unknown, and the receiver assumes a value of 0. In situations where the true altitude is
significantly higher than that, the horizontal position estimate will be noticeably impacted. 2_D
positioning is controlled by OSP MID 136.
Static Navigation
Static Navigation is an operating mode in which the receiver will freeze the position fix when the
speed falls below a set threshold (indicating that the receiver is stationary). The course is also
frozen, and the speed is reported as 0. The navigation solution is unfrozen when the speed
increases above a threshold or when the computed position exceeds a set distance from the
frozen position (indicating that the receiver is again in motion). These thresholds cannot be
changed by the user.
This feature is useful for applications in which very low dynamics are not expected, the classic
example being an automotive application.
Static Navigation is disabled by default, but can be enabled by OSP command MID 143.
Velocity Dead-Reckoning
Velocity dead-reckoning is the use of the last known velocity to propagate the navigation solution
when there are insufficient measurements to calculate an updated solution. It serves to mitigate
the effects of blocked satellite signals by continuing to provide a position output. Note: The
receiver outputs status information which indicates that a solution is being maintained using deadreckoning.
This feature is disabled by default but can be enabl ed using the M ode C ontrol message MID 136.
Valid timeout values are in a range from zero (which disables dead-reckoning) to two minutes.
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SE873 Family Product User Guide Product Features
Jamming Rejec ti on – Continuous Wave (CW) Jamming
Mitigation
Continuous Wave (CW) jamming mitigation improves performance in a system that is affected by
these predictable jamming signals:
• St able j amming signals generated by your system implementation, such as harmonics of
digital clocks and logic switch ing
• Predictable jamming signals in the RF environment (e.g. from collocated transmitters)
When this feature is activated, the process for jamming mitigation is:
1. Detect jamming signals above the noise floor.
2. Isolate and filter frequencies containing jamming signals.
The GNSS signal is constantly monitored for CW jammers and up to eight are detected and
cancelled in each band without any operator intervention.
GPS, GLONASS, and BDS band cancellers are activated and reported using OSP MID 92. T h i s
feature is useful both in the design stage and during the production stage for uncovering issues
related to unexpected jamming. Use OSP MID 220,1 to configure this feature.
Elevation Mask Angle
The default elevation mask angle is 5° which can be changed using OSP MID 139.
5 Hz and 10 Hz Navigation
When this feature is enabled, the receiver starts in 1 Hz mode and continues until it achieves an
over-determined fix with 5 or more satellites. It then computes and outputs solutions 5 or 10 times
per second. Each computation uses fewer, but more frequent satellite observations. In most
situations this gives a better response to vehicle velocity and course changes but might cause
slightly more erratic performance in stationary or low-dynamic situations.
The receiver also attempts to send out 5 or 10 times as many messages per second. The data
rate may need to be increased or the set of schedu led messages be reduced to avoid overloading
the available bandwidth.
For NMEA protocol, with default messages set on (GGA, GSA and RMC output once per cycle
and GSV output once every 5 cycles) output is nearly 1300 characters per second at 5 Hz.
Including start and stop bits, at least 19200 bps is required to avoid running out of bandwidth.
For multi-constellation output, one GNGNS and one GNGSA would be added to each report cycle,
and three GNGSV sentences every 5
Hz. For OSP protocol, CSR recommends a minimum data rate of 115,200 bps.
To enable 5 or 10 Hz Navigation, use a $PSRF103 command or an OSP MID 136 command with
bit 2 of the pos_mode_enable field set to 1.
th
c ycle, requiring a minimum of 38,400 bps data rate at 5
1PPS
The module provides a 1PPS timing pulse. See section 8.4.3 1PPS
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SE873 Family Product User Guide Product Features
Internal LNA
The GNSS engin e has an adjustable gain internal LNA which allows the receiver to compensate
for the use of various external antennas. The default gain (low or high) is determined by the
version of firmware installed in the module. The chart below shows the internal gain modes and
the allowable external gain.
Use the OSP command MID 178,70 to change the gain of the internal LNA.
Passive antenna:
For passive antenna operations, the internal LNA should be in high gain mode. GPIO8 should
normally be left unconnected or connected to monitor the receiver status.
Active antenna (or External LNA) with High Gain firmware:
If an external LNA is used with the internal LNA in high gain mode, total RF gain should not
exceed the recommend limit of 30dB.
When GPIO8 is high, the external LNA should be enabled. When low, it should be disabled.
Active antenna (or External LNA) with Low Gain firmware:
If an external LNA is used with the internal LNA in low gain mode, total RF gain should not
exceed the recommend limit of 30dB.
When GPIO8 is high, the external LNA should be enabled. When low, it should be disabled.
Gain Internal LN A gain Internal LNA NF External Gain Range
High 16 dB 2 dB (typical) 0 to 14 dB
Low 6 dB 6.5 dB (typical) 14 to 24 dB
Table 4-1 Internal gain value and external gain range
Serial I/O Ports
The primary port (TX / RX) can be configured to communicate using UART, I2C, or SPI interface.
It is used for command input and message output.
The secondary port (TX1 / RX1) can be c onfigured to communica te using UA RT or I
These pins are named GPIO 0 and 1.
See section 8.5 Serial I/O Ports - Configuration and Operation for details
2
C interface.
1VV0301216 Rev.4 Page 21 of 69 2018-08-24
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