Ublox MAX-M10S Use and care manual


MAX-M10S
Standard precision GNSS module
Integration manual
Abstract
This document describes the features and application of the u-blox MAX-
M10S module, an ultra-low-power standard precision GNSS receiver for
high-performance asset-tracking applications.
www.u-blox.com
UBX-20053088 - R03
C1-Public

MAX-M10S-Integration manual
Document information
Title MAX-M10S
Subtitle Standard precision GNSS module
Document type Integration manual
Document number UBX-20053088
Revision and date R03 12-Jul-2022
Disclosure restriction C1-Public
This document applies to the following products:
Type number Firmware version IN/PCN reference RN reference
MAX-M10S-00B-01 ROM SPG 5.10 UBX-22012689 UBX-22001426
u-blox or third parties may hold intellectual property rights in the products, names, logos and designs included in this
document. Copying, reproduction, or modification of this document or any part thereof is only permitted with the express
written permission of u-blox. Disclosure to third parties is permitted for clearly public documents only.
The information contained herein is provided "as is" and u-blox assumes no liability for its use. No warranty, either express
or implied, is given, including but not limited to, with respect to the accuracy, correctness, reliability and fitness for a
particular purpose of the information. This document may be revised by u-blox at any time without notice. For the most recent
documents, visit www.u-blox.com.
Copyright © 2022, u-blox AG.
UBX-20053088 - R03

Page 2 of 89
C1-Public

MAX-M10S-Integration manual
Contents
1 System description...............................................................................................................6
1.1 Overview.................................................................................................................................................... 6
1.2 Architecture..............................................................................................................................................6
1.2.1 Block diagram..................................................................................................................................6
1.3 Pin assignment........................................................................................................................................7
2 Receiver functionality.......................................................................................................... 9
2.1 Receiver configuration.................................................................................................9
2.1.1 Basic receiver configuration.........................................................................................................9
2.1.2 Navigation configuration............................................................................................................13
2.2 Augmentation systems.............................................................................................17
2.2.1 SBAS............................................................................................................................................... 18
2.2.2 QZSS SLAS....................................................................................................................................19
2.3 Communication interfaces and PIOs.................................................................... 20
2.3.1 UART............................................................................................................................................... 20
2.3.2 I2C....................................................................................................................................................21
2.3.3 PIOs................................................................................................................................................. 24
2.4 Antenna..........................................................................................................................26
2.4.1 Antenna supervisor..................................................................................................................... 26
2.5 Forcing receiver reset................................................................................................32
2.6 Security.......................................................................................................................... 33
2.6.1 Configuration locking.................................................................................................................. 33
2.7 Power management................................................................................................... 33
2.7.1 Continuous mode.........................................................................................................................33
2.7.2 Power save mode......................................................................................................................... 34
2.7.3 Backup modes.............................................................................................................................. 40
2.8 Time.................................................................................................................................40
2.8.1 Receiver local time.......................................................................................................................40
2.8.2 GNSS time bases.........................................................................................................................41
2.8.3 Navigation epochs....................................................................................................................... 42
2.8.4 iTow timestamps..........................................................................................................................42
2.8.5 Time validity.................................................................................................................................. 43
2.8.6 UTC representation..................................................................................................................... 43
2.8.7 Leap seconds................................................................................................................................ 44
2.8.8 Date ambiguity............................................................................................................................. 44
2.9 Time mark..................................................................................................................... 45
2.10 Time pulse...................................................................................................................46
2.10.1 Recommendations.....................................................................................................................47
2.10.2 Time pulse configuration......................................................................................................... 48
2.11 Time maintenance....................................................................................................49
2.11.1 Real-time clock...........................................................................................................................49
2.11.2 Time assistance.........................................................................................................................49
2.11.3 Frequency assistance...............................................................................................................50
2.11.4 Clock drift assistance...............................................................................................................50
UBX-20053088 - R03

Contents Page 3 of 89
C1-Public

MAX-M10S-Integration manual
2.12 Protection level......................................................................................................... 50
2.12.1 Introduction.................................................................................................................................50
2.12.2 Interface.......................................................................................................................................51
2.12.3 Expected behavior..................................................................................................................... 52
2.13 Multiple GNSS assistance (MGA)....................................................................... 52
2.13.1 Authorization.............................................................................................................................. 53
2.13.2 Preserving MGA and operational data during power-off...................................................53
2.13.3 AssistNow offline.......................................................................................................................53
2.13.4 AssistNow autonomous........................................................................................................... 56
2.14 Data batching............................................................................................................ 59
2.14.1 Introduction.................................................................................................................................59
2.14.2 Setting up the data batching................................................................................................. 59
2.14.3 Retrieval....................................................................................................................................... 60
2.15 CloudLocate................................................................................................................60
2.15.1 CloudLocate measurements................................................................................................... 61
3 Hardware integration......................................................................................................... 62
3.1 Power supply.......................................................................................................................................... 62
3.1.1 VCC..................................................................................................................................................62
3.1.2 V_IO..................................................................................................................................................62
3.1.3 V_BCKP........................................................................................................................................... 62
3.1.4 Supply design examples.............................................................................................................63
3.2 RF interference......................................................................................................................................64
3.2.1 In-band interference.................................................................................................................... 64
3.2.2 Out-of-band interference........................................................................................................... 64
3.2.3 Spectrum analyzer.......................................................................................................................65
3.3 RF front-end...........................................................................................................................................66
3.3.1 Internal LNA modes.....................................................................................................................66
3.3.2 Out-of-band blocking immunity................................................................................................67
3.3.3 Out-of-band rejection..................................................................................................................68
3.3.4 Antenna power supply................................................................................................................ 69
3.4 Layout......................................................................................................................................................69
3.4.1 Package footprint, copper and solder mask.......................................................................... 70
4 Product handling................................................................................................................. 73
4.1 Safety...................................................................................................................................................... 73
4.1.1 ESD precautions...........................................................................................................................73
4.1.2 Safety precautions...................................................................................................................... 73
4.2 Packaging............................................................................................................................................... 74
4.2.1 Reels................................................................................................................................................74
4.2.2 Tapes...............................................................................................................................................74
4.2.3 Moisture sensitivity level............................................................................................................75
4.3 Soldering................................................................................................................................................. 75
Appendix.................................................................................................................................... 79
A Migration....................................................................................................................................................79
B Reference designs....................................................................................................................................81
B.1 Typical design.................................................................................................................................. 81
B.2 Antenna supervisor designs......................................................................................................... 83
C External components.............................................................................................................................. 85
C.1 Standard capacitors....................................................................................................................... 85
UBX-20053088 - R03

Contents Page 4 of 89
C1-Public

MAX-M10S-Integration manual
C.2 Standard resistors.......................................................................................................................... 86
C.3 Inductors........................................................................................................................................... 86
C.4 Operational amplifier...................................................................................................................... 86
C.5 Open drain buffers.......................................................................................................................... 86
C.6 Antenna supervisor switch transistors......................................................................................86
Related documents................................................................................................................ 87
Revision history.......................................................................................................................88
UBX-20053088 - R03

Contents Page 5 of 89
C1-Public

MAX-M10S-Integration manual
1 System description
This section gives an overview of the MAX-M10S receiver, and outlines the basics of operation
with the receiver.
1.1 Overview
The MAX-M10S module features the u-blox M10 standard precision GNSS platform and provides
exceptional sensitivity and acquisition time for all L1 GNSS signals.
MAX-M10S supports concurrent reception of four GNSS (GPS, GLONASS, Galileo, and BeiDou). The
high number of visible satellites enables the receiver to select the best signals. This maximizes the
position availability, in particular under challenging conditions such as in deep urban canyons. u-blox
Super-S (Super-Signal) technology offers great RF sensitivity and can improve the dynamic position
accuracy in non-line-of-sight scenarios.
The extremely low power consumption of 25 mW in continuous tracking mode allows great power
autonomy for all battery-operated devices, such as asset trackers, without compromising on GNSS
performance.
For maximum sensitivity in passive antenna designs, MAX-M10S integrates an LNA followed by a
SAW filter in the RF path.
MAX-M10S offers backwards pin-to-pin compatibility with products from the previous u-blox
generations, which saves the designer's effort and reduces costs when upgrading designs to the
advanced low-power u-blox M10 GNSS technology.
1.2 Architecture
The MAX-M10S receiver provides all the necessary RF and baseband processing to enable multi-
constellation operation. The block diagram below shows the key functionality.
1.2.1 Block diagram
Figure 1: MAX-M10S block diagram
UBX-20053088 - R03

1 System description Page 6 of 89
C1-Public

MAX-M10S-Integration manual
1.3 Pin assignment
Figure 2: MAX-M10S pin assignment
Pin no. Name PIO no. I/O Description Remarks
1 GND - - - Connect to GND
2 TXD 1 O UART TX If not used, leave open. Alternative functions1.
3 RXD 0 I UART RX If not used, leave open. Alternative functions1.
4 TIMEPULSE 4 O Time pulse signal See section TIMEPULSE for more information.
Alternative functions1.
5 EXTINT 5 I External interrupt See EXTINT for more information. Alternative
functions1.
6 V_BCKP - I Backup voltage
supply.
Leave open if no external backup supply. See V_BCKP
for more information.
7 V_IO - I IO voltage supply See V_IO for more information.
8 VCC - I Main voltage supply See VCC for more information.
9 RESET_N - I System reset (active
low)
It has to be low for at least 1 ms to trigger a reset. Leave
open if not used.
See RESET_N section for more information.
10 GND - - - Connect to GND
11 RF_IN - I GNSS signal input The RF signal line is DC blocked internally. The line
must match the 50 Ω impedance.
See sections RF front-end and Layout for more
information about the RF signal considerations.
12 GND - - - Connect to GND
1Alternatively, this pin can be used for OPENDET, SHORTDET, TX_READY, and data batching. Care must be taken when
the assigned function sets the pin as an output.
UBX-20053088 - R03

1 System description Page 7 of 89
C1-Public

MAX-M10S-Integration manual
Pin no. Name PIO no. I/O Description Remarks
13 LNA_EN - O On/Off external LNA
or active antenna
This pin cannot be used for another purpose as it also
controls the internal LNA.
See LNA_EN for more information.
14 VCC_RF - O Output voltage RF
section
This pin supplies a filtered voltage that can be used
for optional external active antenna or LNA. This pin
is internally connected to VCC through a ferrite bead.
15 VIO_SEL - I Voltage selector for
V_IO supply
Connect to GND for 1.8 V supply, or leave open for 3.3
V supply
16 SDA 2 I/O I2C data If not used, leave open. Alternative functions1.
17 SCL 3 I I2C clock If not used, leave open. Alternative functions1.
18 SAFEBOOT_N - I Safeboot mode To enter safeboot mode, set this pin to low at receiver's
startup. Otherwise, leave it open.
The SAFEBOOT_N pin is internally connected to
TIMEPULSE pin through a 1 kΩ series resistor.
Table 1: MAX-M10S pin assignment
UBX-20053088 - R03

1 System description Page 8 of 89
C1-Public

MAX-M10S-Integration manual
2 Receiver functionality
This section provides description of the receiver's functionality and features, and explains how to
configure the receiver for various uses.
2.1 Receiver configuration
This section explains the configurations done when taking the receiver into use.
MAX-M10S is fully configurable with UBX configuration interface keys. The configuration database
in the receiver's RAM holds the current configuration, which is used by the receiver at runtime. It is
constructed on startup of the receiver from several sources of configuration. For more information
on receiver configuration, see the interface description [3].
A configuration setting stored in the RAM remains effective until power-down or reset. The RAM
content is cleared by a RESET_N signal, a UBX-CFG-RST message excluding GNSS stop (resetMode
0x08) and GNSS start (resetMode 0x09), entering software standby mode, using external control
in power save mode (PSM) to enter the inactive state, and entering the off state of the PSM on/off
operation (PSMOO). It is therefore recommended to apply runtime configuration on both RAM and
battery-backed RAM (BBR) layers.
The configuration stored in BBR is also cleared by a RESET_N signal or a UBX-CFG-RST message
with reset mode set to a hardware reset (resetMode 0x00 and 0x04), but otherwise will be used as
long as the backup battery supply remains.
CAUTION The configuration interface has changed from earlier u-blox positioning receivers.
Users must adopt the configuration interface described in this document.
The configuration interface settings are stored in a database consisting of separate configuration
items. An item is made up of a pair consisting of a key ID and a value. Related items are grouped
together and identified under a common group name: CFG-GROUP-*; a convention used in u-center
2 and within this document. Within u-center 2, a configuration group is identified as "Group name"
and the configuration item is identified as the "item name" in the "Device configuration" window.
The UBX messages available to change or poll the configurations are the UBX-CFG-VALSET, UBX-
CFG-VALGET, and UBX-CFG-VALDEL messages. For more information about these messages and
the configuration keys see the configuration interface section in the interface description [3].
2.1.1 Basic receiver configuration
This section summarizes the basic receiver configuration most commonly used.
2.1.1.1 Basic hardware configuration
The MAX-M10S receiver is configured with the default setting during the module production. The
receiver starts up and is fully operational as soon as proper power supply, communication interfaces
and antenna signal from the host application device are connected.
2.1.1.2 Internal LNA mode configuration
The MAX-M10S supports three modes for the internal low-noise amplifier (LNA). The normal-gain
mode is not recommended for MAX-M10S because the integrated LNA already provides sufficient
gain. Low-gain mode is the default. With an active antenna with high external gain, bypass mode
can be used. This can be configured at run time in BBR and RAM layers using the configuration item
CFG-HW-RF_LNA_MODE and applying a software reset by sending UBX-CFG-RST message. Refer
to Forcing receiver reset for more information.
UBX-20053088 - R03

2 Receiver functionality Page 9 of 89
C1-Public

MAX-M10S-Integration manual
The internal LNA mode can also be permanently configured in the receiver's one-time programmable
(OTP) memory. Changes to the bits in the OTP memory cannot be modified after they are
programmed. The OTP configuration is only done once in production, and is subsequently applied
automatically at every startup. The internal LNA mode can be reconfigured in BBR and RAM layers
with the configuration item CFG-HW-RF_LNA_MODE and applying a software reset.
The default low-gain mode is pre-configured in the receiver and does not require configuration in
production. The configuration string for setting the internal LNA in bypass mode in the OTP memory
is given in Table 2.
Once the internal LNA mode is configured to bypass mode, it cannot be reverted to low-gain
mode in the OTP memory.
Internal LNA mode Configuration string
Low gain Default
Bypass B5 62 06 41 10 00 03 00 05 1F 79 B2 0A E5 28 EF 12 05 9F FF FF FF 62 FB
Table 2: Internal LNA mode configuration in OTP memory
To configure the internal LNA in bypass mode in OTP memory:
1. Power up the system.
2. Test the communication interface by polling the UBX-MON-VER message.
3. Send the configuration string in Table 2.
4. Power the receiver off and on or send UBX-CFG-RST message (the reset type must be set to a
hardware reset). The new internal LNA setting is applied at startup.
5. Verify that the configuration item is correctly set by polling CFG-HW-RF_LNA_MODE at RAM
layer using the UBX-CFG-VALGET message.
6. The OTP memory configuration is completed.
2.1.1.3 GNSS signal configuration
MAX-M10S supports concurrent reception of four major GNSS constellations using the GPS L1C/A,
Galileo E1, BeiDou B1C, and GLONASS L1OF signals. BeiDou B1I signal is also supported, but cannot
be used simultaneously with BeiDou B1C or GLONASS L1OF signals. The default configuration is
concurrent reception of GPS, Galileo and BeiDou B1I with QZSS and SBAS enabled.
BeiDou B1I signal cannot be used simultaneously with BeiDou B1C or GLONASS L1OF
signals.
GNSS constellations and signals can be configured using the CFG-SIGNAL-* configuration group.
Each GNSS constellation can be enabled or disabled independently except for QZSS and SBAS,
which are functional only with GPS. In addition to the configuration key for each constellation, there
is a configuration key for each signal supported by the firmware. Unsupported combinations will be
rejected with a UBX-ACK-NAK message, and the warning "invalid sig cfg" will be sent via UBX-INF
and NMEA-TXT messages (if enabled).
For example, if CFG-SIGNAL-GPS_ENA is set to zero, all signals from the GPS constellation are
disabled. Alternatively, if CFG-SIGNAL-GPS_L1CA_ENA is set to zero, only the GPS L1 C/A signal is
disabled.
It is recommended to enable QZSS L1C/A when GPS L1C/A is enabled in order to mitigate
possible cross-correlation issues between the signals.
Refer to the interface description [3] for more information on the CFG-SIGNAL-* configuration group.
UBX-20053088 - R03

2 Receiver functionality Page 10 of 89
C1-Public

MAX-M10S-Integration manual
2.1.1.4 Communication interface configuration
Several configuration groups allow configuring the operation mode of the communication
interfaces. These include parameters for the data framing, transfer rate and enabled input/output
protocols. See Communication interfaces and PIOs section for details. The configuration groups
available for each interface are:
Interface Configuration groups
UART CFG-UART1-*, CFG-UART1INPROT-*, CFG-UART1OUTPROT-*
I2C CFG-I2C-*, CFG-I2CINPROT-*, CFG-I2COUTPROT-*, CFG-TXREADY-*
Table 3: Interface configuration
The UART baudrate in MAX-M10S is configured to 9600 baud which is different to the
firmware default. This ensures backwards compatibility with previous generations of u-blox
MAX modules.
2.1.1.5 Message output configuration
The receiver supports two protocols for output messages: industry-standard NMEA and u-blox UBX.
Any message type can be enabled or disabled individually and the output rate is configurable.
The message output rate is related to the frequency of an event. For example, the output message
UBX-NAV-PVT (position, velocity, and time solution) is related to the navigation event, which
generates a navigation epoch. In this case, the rate for each navigation epoch is defined by the
configuration keys CFG-RATE-MEAS and CFG-RATE-NAV. For example, a value of 1000 ms in CFG-
RATE-MEAS indicates that a measurement is done every second. If CFG-RATE-NAV is set to one (1),
the solution is calculated for every measurement. This means that a navigation epoch is calculated
every 1000 ms. If the rate is set to two (2), only the second measurement is used and the navigation
epoch is calculated every two seconds. The same result is obtained if CFG-RATE-MEAS is set to
2000 ms, and CFG-RATE-NAV is set to one (1). Every 2000 ms a measurement is done, and in
every measurement, a navigation epoch is calculated. However, this second option demands fewer
resources and is the correct procedure when the navigation rate is changed. Setting a navigation
rate value higher than one (1) is only needed when it is required that the raw measurement data is
output at a higher rate than the navigation data.
The output rate for each message is defined in the CFG-MSGOUT-* configuration group. If
the output rate of the message is set to one (1) on the UART interface, CFG-MSGOUT-
UBX_NAV_PVT_UART1 = 1, the message is output for every navigation epoch. If the rate is set
to two (2), the message is output every other navigation epoch. If the rate is zero (0), then the
corresponding message will not be output. As seen in this example, the rates of the output
messages are individually configurable per communication interface.
Some messages, such as UBX-MON-VER, are non-periodic and will only be output as an answer to
a poll request.
The UBX-INF-* and NMEA-Standard-TXT information messages are non-periodic output messages
that do not have a message rate configuration. Instead they can be enabled for each communication
interface via the CFG-INFMSG-* configuration group.
All message output is additionally subject to the protocol configuration of the
communication interfaces. Messages of a given protocol will not be output unless the
protocol is enabled for output on the interface. See Communication interface configuration
for details.
The output rate of the NMEA-GxGSV message on the UART interface is configured to 5
in MAX-M10S, which is different to the firmware default in order to avoid overloading the
communication interface and buffers.
UBX-20053088 - R03

2 Receiver functionality Page 11 of 89
C1-Public

MAX-M10S-Integration manual
2.1.1.6 Antenna supervisor configuration
This section gives an overview of the antenna supervisor configuration keys. The implementation of
the antenna supervisor and a detailed description can be found in Antenna supervisor.
The antenna supervisor is used to control an active antenna. The configuration of the antenna
supervisor allows the following:
• Control voltage supply to the antenna, which allows the antenna supervisor to cut power to the
antenna in the event of a short circuit or optimize power to the antenna in power save modes.
• Detect a short circuit in the antenna and automatically recover the antenna supply after the
short circuit is no longer present.
• Detect an open circuit, which can be used to indicate if the antenna has been disconnected.
Using some antenna supervisor features may require disabling the UART or I2C interface
and reconfiguring the PIOs as antenna supervisor pins.
Table 4 describes the configuration items.
Configuration item Description Comments
CFG-HW-ANT_CFG_VOLTCTRL Enable active antenna voltage control
CFG-HW-ANT_CFG_SHORTDET Enable short circuit detection
CFG-HW-ANT_CFG_SHORTDET_POL Short antenna detection polarity Set to 1 if the required logic polarity is
active-low (default).
CFG-HW-ANT_CFG_OPENDET Enable open circuit detection
CFG-HW-ANT_CFG_OPENDET_POL Open antenna detection polarity Set to 1 if the required logic polarity is
active-low (default).
CFG-HW-ANT_CFG_PWRDOWN Power down antenna supply if short
circuit is detected
Requires CFG-HW-
ANT_CFG_VOLTCTRL and CFG-HW-
ANT_CFG_SHORTDET to be enabled.
CFG-HW-ANT_CFG_PWRDOWN_POL Power down antenna logic polarity Set to 1 if the required logic polarity is
active-high (default).
CFG-HW-ANT_CFG_RECOVER Enable auto-recovery in the event of a
short circuit
To use this feature, enable short
circuit detection and CFG-HW-
ANT_CFG_PWRDOWN.
CFG-HW-ANT_SUP_SWITCH_PIN PIO number of the pin used for switching
antenna supply
PIO5 is recommended if available. This
pin can be used as an LNA_EN signal
to control an external LNA, especially
if software standby mode or power
save mode on/off (PSMOO) operation is
used.
CFG-HW-ANT_SUP_SHORT_PIN PIO number of the pin used for detecting
a short circuit in the antenna supply
UART or I2C pins can be used for the
short detection, depending on which
interface is used for communication.
CFG-HW-ANT_SUP_OPEN_PIN PIO number of the pin used for detecting
open/disconnected antenna
UART or I2C pins can be used for the
short detection, depending on which
interface is used for communication.
Table 4: Antenna supervisor configuration
It is possible to obtain the status of the antenna supervisor from the UBX-MON-RF message. Refer
to the interface manual for the description of the antStatus and antPower fields [3]. In addition, any
changes in the status of the antenna supervisor are reported to the host interface as ANTSTATUS
in NMEA notice messages.
ANTSTATUS Description
OFF Antenna is off
ON Antenna is on
UBX-20053088 - R03

2 Receiver functionality Page 12 of 89
C1-Public

MAX-M10S-Integration manual
ANTSTATUS Description
DONTKNOW Antenna power status is not known
Table 5: Antenna power status
2.1.2 Navigation configuration
This section presents various configuration options related to the navigation engine. These options
can be configured through CFG-NAVSPG-* configuration keys.
2.1.2.1 Dynamic platform
The dynamic platform model can be configured through the CFG-NAVSPG-DYNMODEL
configuration item. For the supported dynamic platform models and their details, see Table 6 and
Table 7.
Platform Description
Portable Applications with low acceleration, e.g. portable devices. Suitable for most situations.
Stationary Used in timing applications (antenna must be stationary) or other stationary applications.
Velocity restricted to 0 m/s. Zero dynamics assumed.
Pedestrian Applications with low acceleration and speed, e.g. how a pedestrian would move. Low
acceleration assumed.
Automotive Used for applications with equivalent dynamics to those of a passenger car. Low vertical
acceleration assumed.
At sea Recommended for applications at sea, with zero vertical velocity. Zero vertical velocity assumed.
Sea level assumed.
Airborne <1g Used for applications with a higher dynamic range and greater vertical acceleration than a
passenger car. No 2D position fixes supported.
Airborne <2g Recommended for typical airborne environments. No 2D position fixes supported.
Airborne <4g Only recommended for extremely dynamic environments. No 2D position fixes supported.
Wrist Only recommended for wrist-worn applications. Receiver will filter out arm motion.
Table 6: Dynamic platform models
Platform Max altitude [m] Max horizontal
velocity [m/s]
Max vertical velocity
[m/s]
Sanity check type Max
position
deviation
Portable 12000 310 50 Altitude and velocity Medium
Stationary 9000 10 6 Altitude and velocity Small
Pedestrian 9000 30 20 Altitude and velocity Small
Automotive 6000 100 15 Altitude and velocity Medium
At sea 500 25 5 Altitude and velocity Medium
Airborne <1g 80000 100 6400 Altitude Large
Airborne <2g 80000 250 10000 Altitude Large
Airborne <4g 80000 500 20000 Altitude Large
Wrist 9000 30 20 Altitude and velocity Medium
Table 7: Dynamic platform model details
Applying dynamic platform models designed for high acceleration systems (e.g. airborne <2g) can
result in a higher standard deviation in the reported position.
If a sanity check against a limit of the dynamic platform model fails, then the position solution
becomes invalid. Table 7 shows the types of sanity checks which are applied for a particular dynamic
platform model.
UBX-20053088 - R03

2 Receiver functionality Page 13 of 89
C1-Public

MAX-M10S-Integration manual
2.1.2.2 Navigation input filters
The navigation input filters in the CFG-NAVSPG-* configuration group control how the navigation
engine handles the input data that comes from the satellite signal.
Configuration item Description
CFG-NAVSPG-FIXMODE By default, the receiver calculates a 3D position fix if possible but reverts to 2D
position if necessary (auto 2D/3D). The receiver can be forced to only calculate 2D
(2D only) or 3D (3D only) positions.
CFG-NAVSPG-CONSTR_ALT, CFG-
NAVSPG-CONSTR_ALTVAR
The fixed altitude is used if fixMode is set to 2D only. A variance greater than zero
must also be supplied.
CFG-NAVSPG-INFIL_MINELEV Minimum elevation of a satellite above the horizon to be used in the navigation
solution. Low-elevation satellites may provide degraded accuracy, due to the long
signal path through the atmosphere.
CFG-NAVSPG-INFIL_MINSVS, CFG-
NAVSPG-INFIL_MAXSVS
Minimum and maximum number of satellites to use in the navigation solution.
There is an absolute maximum limit of 32 satellites that can be used for navigation.
CFG-NAVSPG-INFIL_NCNOTHRS,
CFG-NAVSPG-INFIL_CNOTHRS
A navigation solution will only be attempted if there is at least the given number of
satellites with signals at least as strong as the given threshold.
Table 8: Navigation input filter parameters
If the receiver only has three satellites for calculating a position, the navigation algorithm uses a
constant altitude to compensate for the missing fourth satellite. When a satellite is lost after a
successful 3D fix (min four satellites available), the altitude is kept constant at the last known value.
This is called a 2D fix.
u-blox receivers do not calculate any navigation solution with less than three satellites.
2.1.2.3 Navigation output filters
The result of a navigation solution is initially classified by the fix type (as detailed in the fixType
field of UBX-NAV-PVT message). This distinguishes between failures to obtain a fix at all ("No Fix")
and cases where a fix has been achieved, which are further subdivided into specific types of fixes
(for example, 2D, 3D ).
Where a fix has been achieved, the fix is checked to determine whether it is valid or not. A fix is only
valid if it passes the navigation output filters as defined in CFG-NAVSPG-OUTFIL. In particular, both
PDOP and accuracy values must be below the respective limits.
Important: Users are recommended to check the gnssFixOK flag in the UBX-NAV-PVT or
the NMEA valid flag. Fixes not marked as valid should not be used.
UBX-NAV-STATUS message also reports whether a fix is valid in the gpsFixOK flag. These
messages have only been retained for backwards compatibility and it is recommended to use the
UBX-NAV-PVT message.
2.1.2.4 Odometer filters
2.1.2.4.1 Speed (3D) low-pass filter
The CFG-ODO-OUTLPVEL configuration item activates a speed (3D) low-pass filter. The output of
the speed low-pass filter is available in the UBX-NAV-VELNED message (speed field). The filtering
level can be set via the CFG-ODO-VELLPGAIN configuration item and must be between 0 (heavy low-
pass filtering) and 255 (weak low-pass filtering).
The internal filter gain is computed as a function of speed. Therefore, the level as defined in
the CFG-ODO-VELLPGAIN configuration item defines the nominal filtering level for speeds
below 5 m/s.
UBX-20053088 - R03

2 Receiver functionality Page 14 of 89
C1-Public

MAX-M10S-Integration manual
2.1.2.4.2 Course over ground low-pass filter
The CFG-ODO-OUTLPCOG configuration item activates a course over ground low-pass filter when
the speed is below 8 m/s. The output of the course over ground (also named heading of motion
2D) low-pass filter is available in the UBX-NAV-PVT message (headMot field), UBX-NAV-VELNED
message (heading field), NMEA-RMC message (cog field), and NMEA-VTG message (cogt field).
The filtering level can be set via the CFG-ODO-COGLPGAIN configuration item and must be between
0 (heavy low-pass filtering) and 255 (weak low-pass filtering).
The filtering level as defined in the CFG-ODO-COGLPGAIN configuration item defines the
filter gain for speeds below 8 m/s. If the speed is 8 m/s or higher, no course over ground low-
pass filtering is performed.
2.1.2.4.3 Low-speed course over ground filter
The CFG-ODO-USE_COG configuration item activates this feature and the CFG-ODO-
COGMAXSPEED, CFG-ODO-COGMAXPOSACC configuration items are used to configure a low-
speed course over ground filter (also named heading of motion 2D). This filter derives the course
over ground from position at very low speed. The output of the low-speed course over ground filter
is available in the UBX-NAV-PVT message (headMot field), UBX-NAV-VELNED message (heading
field), NMEA-RMC message (cog field) and NMEA-VTG message (cogt field). If the low-speed
course over ground filter is not configured, then the course over ground is computed as described
in section Freezing the course over ground.
2.1.2.5 Static hold
Static hold mode allows the navigation algorithms to decrease the noise in the position output when
the velocity is below a predefined "Static Hold Threshold" level. This reduces the position wander
caused by environmental factors such as multi-path and improves position accuracy especially in
stationary applications. By default, static hold mode is disabled.
The CFG-MOT-GNSSSPEED_THRS configuration item defines the static hold speed threshold. If
the speed drops below the defined "Static Hold Threshold", static hold mode will be activated. Once
static hold mode is active, the position output is kept static and the velocity is set to zero until there
is evidence of movement again. Such evidence can be velocity, acceleration, changes of the valid flag
(for example, position accuracy estimate exceeding the position accuracy mask, see also section
Navigation output filters ), position displacement, etc.
The CFG-MOT-GNSSDIST_THRS configuration item defines the static hold distance threshold. If
the distance between the estimated position and the static hold position exceeds the defined
threshold, static hold mode is suspended or deactivated until there is evidence of no movement.
UBX-20053088 - R03

2 Receiver functionality Page 15 of 89
C1-Public

MAX-M10S-Integration manual
Figure 3: Position output in static hold mode
Figure 4: Flowchart of static hold mode
UBX-20053088 - R03

2 Receiver functionality Page 16 of 89
C1-Public

MAX-M10S-Integration manual
2.1.2.6 Freezing the course over ground
If the low-speed course over ground filter is deactivated or inactive (see section Low-speed course
over ground filter), the receiver derives the course over ground from the GNSS velocity information.
If the velocity cannot be calculated with sufficient accuracy (for example, with bad signals) or if
the absolute speed value is very low (under 0.1 m/s) then the course over ground value becomes
inaccurate too. In this case the course over ground value is frozen, that is, the previous value is kept
and its accuracy degrades over time. These frozen values will not be output in the NMEA messages
NMEA-RMC and NMEA-VTG unless the NMEA protocol is explicitly configured to do so (see NMEA
protocol configuration in the applicable interface description [3]).
Figure 5: Flowchart of course over ground freezing
2.1.2.7 Super-Signal (Super-S) technology
In normal operating conditions, low signal strength (that is, signal attenuation) indicates possible
degradation due to multi-path. The receiver trusts such signals less in order to preserve the
quality of the position solution in poor signal environments. This feature can result in degraded
performance in situations where the signals are attenuated for another reason, for example due
to antenna placement. In this case, the weak signal compensation feature can be used to restore
normal performance. There are three possible modes:
• Disabled: no weak signal compensation is performed
• Automatic: the receiver automatically estimates and compensates for the weak signal
• Configured: the receiver compensates for the weak signal based on a configured value
These modes can be selected using CFG-NAVSPG-SIGATTCOMP. In the case of the "configured"
mode, the user should input the maximum C/N0 observed in a clear-sky environment, excluding any
outliers or unusually high values. Choose the configured value carefully, as it can have a large impact
on the receiver performance.
UBX-20053088 - R03

2 Receiver functionality Page 17 of 89
C1-Public

MAX-M10S-Integration manual
2.2 Augmentation systems
2.2.1 SBAS
MAX-M10S is capable of receiving multiple SBAS signals concurrently, even from different SBAS
systems (WAAS, EGNOS, MSAS, etc.). SBAS signals are recommended to be used only for correction
data. SBAS signals can also be used for navigation, however they have low weighting and therefore
only a minor impact on the navigation solution.
For receiving correction data, the MAX-M10S automatically chooses the best SBAS satellite as its
primary source. It will select only one since the information received from other SBAS satellites is
redundant and could be inconsistent. The selection strategy is determined by the proximity of the
satellites, the services offered by the satellite, the configuration of the receiver (test mode allowed/
disallowed, integrity enabled/disabled) and the signal link quality to the satellite.
If corrections are available from the chosen SBAS satellite and used in the navigation calculation, the
differential status will be indicated in several output messages such as UBX-NAV-PVT, UBX-NAV-
STATUS, UBX-NAV-SAT, NMEA-GGA, NMEA-GLL, NMEA-RMC, and NMEA-GNS. The UBX-NAV-
SBAS message provides detailed information about which corrections are available and applied.
Refer to the interface description [3] for a detailed description of the messages.
The most important SBAS feature for accuracy improvement is ionosphere correction. The
measured data from regional Ranging and Integrity Monitoring Stations (RIMS) are combined to
make a Total Electron Content (TEC) map. This map is transferred to the receiver via SBAS satellites
to allow a correction of the ionosphere error on each received signal.
Message type Message content Source
0(0/2) Test mode All
1 PRN mask assignment Primary
2, 3, 4, 5 Fast corrections Primary
6 Integrity Primary
7 Fast correction degradation Primary
9 Satellite navigation (ephemeris) All
10 Degradation Primary
12 Time offset Primary
17 Satellite almanac All
18 Ionosphere grid point assignment Primary
24 Mixed fast / long-term corrections Primary
25 Long-term corrections Primary
26 Ionosphere delays Primary
Table 9: Supported SBAS messages
Each satellite serves a specific region and its correction signal is only useful within that region.
Planning is crucial to determine the best possible configuration, especially in areas where signals
from different SBAS systems can be received:
•Example 1 - SBAS receiver in North America: In eastern parts of North America, make sure
that EGNOS satellites do not take preference over WAAS satellites. The satellite signals from
the EGNOS system should be disallowed by using the PRN mask.
•Example 2 - SBAS receiver in Europe: Some WAAS satellite signals can be received in western
parts of Europe, therefore it is recommended that the satellites from all but the EGNOS system
should be disallowed using the PRN mask.
UBX-20053088 - R03

2 Receiver functionality Page 18 of 89
C1-Public

MAX-M10S-Integration manual
Although u-blox receivers try to select the best available SBAS correction data, it is
recommended to configure them to exclude unwanted SBAS satellites.
To configure the SBAS functionality, use the CFG-SBAS-* configuration group.
Parameter Description
CFG-SIGNAL-SBAS_ENA Enabled/disabled status of the SBAS subsystem
CFG-SBAS-USE_TESTMODE Allow/disallow SBAS usage from satellites in test mode
CFG-SBAS-USE_RANGING Use the SBAS satellites for navigation (ranging)
CFG-SBAS-USE_DIFFCORR Combined enable/disable switch for fast, long-term, and ionosphere corrections
CFG-SBAS-USE_INTEGRITY Apply integrity information data
CFG-SBAS-PRNSCANMASK Allows selectively enabling/disabling SBAS satellites
Table 10: SBAS configuration parameters
When SBAS integrity data is applied, the navigation engine stops using all signals for which
no integrity data is available (including all non-GPS signals). It is not recommended to enable
SBAS integrity on borders of SBAS service regions in order not to inadvertently restrict the
number of available signals.
SBAS integrity information is required for at least five GPS satellites. If this condition is not
met, SBAS integrity data will not be applied.
When the receiver switches from a solution using correction data to a standard position
solution, the reference frame of the output position will switch from that of the correction
data to that of the standard position solution. For an SBAS solution, this reference frame
will be aligned within a few cm of WGS84 (and modern ITRF realizations).
2.2.2 QZSS SLAS
QZSS SLAS (Sub-meter Level Augmentation Service) is an augmentation technology, which
provides correction data for pseudoranges of GPS, QZSS, and other major GNSS satellites. The
correction stream is transmitted on the L1S signal at the L1 frequency (1575.42 MHz).
For more information on QZSS SLAS, visit qzss.go.jp/en/.
Multiple QZSS SLAS signals can be received simultaneously. When receiving QZSS SLAS correction
data, MAX-M10S module will autonomously select the best QZSS satellite. The selection strategy
is determined by the quality of the QZSS L1S signals, the receiver configuration (test mode allowed
or not), and the location of the receiver with respect to the QZSS SLAS coverage area. When outside
of this coverage area, the receiver will likely fall back to using SBAS corrections.
If QZSS SLAS corrections are used in the navigation solution, the differential status will be indicated
in several output messages such as UBX-NAV-PVT, UBX-NAV-STATUS, UBX-NAV-SAT, NMEA-
GGA, NMEA-GLL, NMEA-RMC, and NMEA-GNS. The UBX-NAV-SLAS message provides detailed
information about which corrections are available and applied. Refer to the interface description [3]
for a detailed description of the messages.
Message type Message content
0 Test mode
47 Monitoring station information
48 PRN mask
49 Data issue number
50 DGPS correction
51 Satellite health
Table 11: Supported QZSS L1S SLAS messages for navigation enhancement
UBX-20053088 - R03

2 Receiver functionality Page 19 of 89
C1-Public

MAX-M10S-Integration manual
Use the configuration key CFG-SIGNAL-QZSS_L1S_ENA to enable QZSS L1S signal. For further
QZSS SLAS functionality, use the CFG-QZSS-USE_SLAS* configuration keys.
Parameter Description
CFG-QZSS-USE_SLAS_DGNSS Apply QZSS SLAS corrections
CFG-QZSS-USE_SLAS_TESTMODE Allow the correction provided by QZSS satellites that are in test mode
CFG-QZSS-
USE_SLAS_RAIM_UNCORR
If this configuration is set, the receiver will try to estimate the position by using only
corrected measurements; if all corrected measurements are not available, it will not
use any corrections. If this configuration is not set, the receiver will mix corrected
and uncorrected measurements for the navigation solution.
Table 12: QZSS SLAS configuration parameters
If the RAIM option is set, QZSS is the only GNSS time system that measurements can
observe.
2.3 Communication interfaces and PIOs
The MAX-M10S supports communication over UART and I2C2 interfaces for communication with
a host CPU. Each protocol can be enabled on several interfaces at the same time with individual
settings for, for example, baud rate, message rates, and so on. In MAX-M10S, several protocols can
be enabled on a single interface the same time.
2.3.1 UART
The MAX-M10S supports a Universal Asynchronous Receiver/Transmitter (UART) port consisting
of an RX and a TX line. UART can be used as a host interface which supports a configurable baud
rate and protocol selection.
Neither handshaking signals nor hardware flow control signals are available in the UART interface.
This serial interface operates in asynchronous mode. The baud rate can be configured for the
serial interface. However, there is no support for setting a different baud rate for reception and
transmission.
The UART RX interface will be disabled when more than 100 frame errors are detected
during a one-second period. This can happen if the wrong baud rate is used or the UART RX
pin is grounded. An error message appears when the UART RX interface is re-enabled at the
end of the one-second period.
Baud rate Data bits Parity Stop bits
4800 8 none 1
9600 8 none 1
19200 8 none 1
38400 8 none 1
57600 8 none 1
115200 8 none 1
230400 8 none 1
460800 8 none 1
921600 8 none 1
Table 13: Possible UART interface configurations
The default baud rate is 9600 baud. Using a low baud rate may cause buffering problems.
2I2C is a registered trademark of Philips/NXP.
UBX-20053088 - R03

2 Receiver functionality Page 20 of 89
C1-Public