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NEO-M9N - Integration manual

3.1.7.5 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 (e.g., 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, i.e. the previous value is kept and its accuracy
is degraded 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 [

Figure 4: Flowchart of the course over ground freezing

3.1.7.6 Weak signal compensation

In  normal  operating  conditions,  low  signal  strength  (i.e.  signal  attenuation)  indicates  likely
contamination by multipath. 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. The conﬁgured value can have a large impact on the receiver
performance, so it should be chosen carefully.

UBX-19014286 - R07

3 Receiver functionality

Page 15 of 95

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Содержание M9

Страница 1: ...Integration manual describing the u blox NEO M9N GNSS module NEO M9N oﬀers ultra robust meter level GNSS positioning performance with concurrent reception of up to four GNSS GPS GLONASS BeiDou Galileo in a 12 2 x 16 0 mm package www u blox com UBX 19014286 R07 C1 Public ...

Страница 2: ...s logos and designs included in this document Copying reproduction modiﬁcation or disclosure to third parties of this document or any part thereof is only permitted with the express written permission of u blox 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 th...

Страница 3: ...n 17 3 3 2 Interface 17 3 3 3 Geofence state evaluation 18 3 3 4 Using a PIO for geofence state output 18 3 4 Logging 18 3 4 1 Introduction 18 3 4 2 Setting the logging system up 19 3 4 3 Information about the log 19 3 4 4 Recording 20 3 4 5 Retrieval 21 3 4 6 Command message acknowledgment 22 3 5 Data batching 22 3 5 1 Introduction 22 3 5 2 Setting up the data batching 22 3 5 3 Retrieval 23 3 6 S...

Страница 4: ...tation 54 3 12 7 Leap seconds 55 3 12 8 Real time clock 55 3 12 9 Date 55 3 13 Timing functionality 56 3 13 1 Time pulse 56 3 13 2 Timemark 60 3 14 Security 61 3 14 1 Spooﬁng detection monitoring 61 3 14 2 Jamming interference detection monitoring 62 3 14 3 GNSS receiver integrity 63 3 15 u blox protocol feature descriptions 63 3 15 1 Broadcast navigation data 63 3 16 Forcing a receiver reset 67 3...

Страница 5: ... 8 1 Placement 79 4 8 2 Thermal management 79 4 8 3 Package footprint copper and paste mask 79 4 8 4 Layout guidance 81 4 9 Design guidance 82 4 9 1 General considerations 82 4 9 2 Backup battery 83 4 9 3 RF front end circuit options 83 4 9 4 Antenna RF input 84 4 9 5 Ground pads 84 4 9 6 Schematic design 84 4 9 7 Layout design in guideline 84 5 Product handling 85 5 1 ESD handling precautions 85 ...

Страница 6: ...t source of information on all aspects of NEO M9N system software and hardware design The purpose of this document is to provide guidelines for a successful integration of the receiver with the customer s end product UBX 19014286 R07 1 Integration manual overview Page 6 of 95 C1 Public ...

Страница 7: ...aximizes the position accuracy in particular under challenging conditions such as deep urban canyons u blox M9 receivers detect jamming and spooﬁng events and report them to the host which allows the system to react to such events Advanced ﬁltering algorithms mitigate the impact of RF interference and jamming thus enabling the product to operate as intended The receiver also provides higher naviga...

Страница 8: ... 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 and within this document Within u center a conﬁguration group is identiﬁed as Group name and the conﬁguration item is identiﬁed as the item name under the Generation 9...

Страница 9: ...ces and antenna signal from the application have been connected 3 1 4 2 Communication interface conﬁguration Several conﬁguration groups allow operation mode conﬁguration of the various communication interfaces These include parameters for the data framing transfer rate and enabled input output protocols See Communication interfaces section for details The conﬁguration groups available for each in...

Страница 10: ...es Version 3 October 7 2016 The RTCM speciﬁcation is currently at version 3 3 and RTCM version 2 messages are not supported by this standard To modify the RTCM input output settings see the conﬁguration section in the applicable interface description 2 3 1 5 1 NTRIP networked transport of RTCM via internet protocol Networked Transport of RTCM via internet protocol or NTRIP is an open standard prot...

Страница 11: ...n Table 3 and Table 4 below Platform Description Portable default 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 acceler...

Страница 12: ... to the long signal path through the atmosphere CFG NAVSPG INFIL_NCNOTHRS CFG NAVSPG INFIL_CNOTHRS A navigation solution will only be attempted if there are at least the given number of SVs with signals at least as strong as the given threshold Table 5 Navigation input ﬁlter parameters If the receiver only has three satellites for calculating a position the navigation algorithm uses a constant alt...

Страница 13: ...O USE_COG activates this feature and the CFG ODO COGMAXSPEED CFG ODO COGMAXPOSACC conﬁguration items oﬀer the possibility 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 published in the UBX NAV PVT message headMot ﬁeld UBX NAV VELNED me...

Страница 14: ...NEO M9N Integration manual Figure 2 Position publication in static hold mode Figure 3 Flowchart of the static hold mode UBX 19014286 R07 3 Receiver functionality Page 14 of 95 C1 Public ...

Страница 15: ...ng conditions low signal strength i e signal attenuation indicates likely contamination by multipath 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 si...

Страница 16: ...MS 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...

Страница 17: ...ot met SBAS integrity data will not be applied SBAS is only used if no correction services are available If the connection stream is lost during the operation the receiver will switch to using the SBAS corrections after the time set in CFG NAVSPG CONSTR_DGNSSTO 60 s by default has elapsed When the receiver switches from a solution using correction data to a standard position solution the reference...

Страница 18: ...ce state output This feature can be used for example for waking up a sleeping host when a deﬁned geofence condition is reached The receiver will toggle the assigned pin according to the combined geofence state Due to hardware restrictions the geofence unknown state is not conﬁgurable and is always represented as HIGH If the receiver is in the software backup mode or in the reset state the pin will...

Страница 19: ...circular log If the log is circular a set of older log entries will be deleted when it ﬁlls up and the space freed up is used for new log entries By contrast if a non circular log becomes full then new entries which do not ﬁt will be rejected UBX LOG CREATE also causes the logging system to start up so that further logging messages can be processed The logging system will start up automatically on...

Страница 20: ...or if all of MIN_INTERVAL TIME_THRS SPEED_THRS or POSITION_THRS thresholds are exceeded If a threshold is set to zero it is ignored Position ﬁxes are only recorded if a valid ﬁx is obtained Failed and invalid ﬁxes are not recorded Position ﬁxes are compressed to reduce the amount of ﬂash space used In order to improve the compression the ﬁx values are rounded This means that the values returned by...

Страница 21: ...rocessing is stopped during the transfer see UBX CFG RST UBX LOG RETRIEVE can specify a start entry index and entry count The maximum number of entries that can be returned in response to a single UBX LOG RETRIEVE message is 256 If more entries than this are required the message will need to be sent multiple times with diﬀerent startEntry indices It might be useful to stop recording via CFG_LOGFIL...

Страница 22: ...essage Description UBX MON BATCH Provides information about the buﬀer ﬁll level and dropped data due to overrun UBX LOG RETRIEVEBATCH Starts the batch retrieval process UBX LOG BATCH A batch entry returned by the receiver Table 11 Batching related messages 3 5 2 Setting up the data batching Data batching is disabled per default and it has to be conﬁgured before use via the CFG BATCH conﬁguration g...

Страница 23: ...X LOG BATCH messages with the batched ﬁxes To maximize the speed of transfer it is recommended that a high communications data rate is used The receiver will discard retrieval request while processing a previous UBX LOG RETRIEVEBATCH message The receiver does not acknowledge the reception of UBX LOG RETRIEVEBATCH the response that the host should expect are the reply messages 3 6 Spectrum analyzer...

Страница 24: ...dish line represents the frozen spectrum before modifying the external gain while the black line represents the current measurement Figure 9 Spectrum analyzer view in u center with the option view hold selected By changing the number of constellations enabled the span widens or narrows This has a direct impact on the spectrum resolution as the number of frequencies measured is ﬁxed at 256 For furt...

Страница 25: ...ed oﬀ so it must be either supplied or enabled by the VCC For the I2C line a dual bidirectional bus buﬀer is needed Figure 10 NEO M9N interface isolation 3 7 1 UART A Universal Asynchronous Receiver Transmitter UART port consists of an RX and a TX line Neither handshaking signals nor hardware ﬂow control signals are available The UART interface protocol and baud rate can be conﬁgured but there is ...

Страница 26: ...ency is 400 kHz the maximum transfer rate is 400 kb s The SCL and SDA pins have internal pull up resistors which should be suﬃcient for most applications However depending on the speed of the host and the load on the I2C lines additional external pull up resistors may be necessary To use the I2C interface D_SEL pin must be left open In designs where the host uses the same I2C bus to communicate wi...

Страница 27: ...rom the master the 7 bit device address and the RW bit which is a logic low for write access are clocked onto the bus by the master transmitter The receiver answers with an acknowledge logic low to indicate that it recognizes the address Next the 8 bit address of the register to be read must be written to the bus Following the receiver s acknowledgment the master again triggers a start condition a...

Страница 28: ...ess The receiver does not provide any write access except for writing UBX and NMEA messages to the receiver such as conﬁguration or aiding data Therefore the register set mentioned in the section Read access is not writeable Following the start condition from the master the 7 bit device address and the RW bit which is a logic low for write access are clocked onto the bus by the master transmitter ...

Страница 29: ... To prevent the receiver from being busy parsing incoming data the parsing process is stopped after 50 subsequent bytes containing 0xFF The parsing process is re enabled with the ﬁrst byte not equal to 0xFF If the receiver has no more data to send it sets MISO to logic high i e all bytes transmitted decode to 0xFF An eﬃcient parser in the host will ignore all 0xFF bytes which are not part of a mes...

Страница 30: ...r supply The V_USB pin is used to detect the availability of the USB port i e whether the receiver is connected to a USB host The receiver draws only minimal amount of current 1 mA from V_USB USB suspend mode is not supported USB bus powered mode is not supported It is important to connect V_USB to ground and leave data lines open when the USB interface is not used in an application The voltage ra...

Страница 31: ...1 SPI_MOSI UART1 RXD 18 SPI_CS_N I2C SDA 19 SPI_CLK I2C SCL Table 16 D_SEL conﬁguration 3 8 2 RESET_N The NEO M9N provides the ability to reset the receiver The RESET_N pin is an input only pin with an internal pull up resistor Driving RESET_N low for at least 100 ms will trigger a cold start The RESET_N pin will delete all information and trigger a cold start It should only be used as a recovery ...

Страница 32: ...message does not indicate if the TX READY conﬁguration is successfully set it only indicates the successful conﬁguration of the port To validate successful conﬁguration of the TX_READY pin the port conﬁguration should be read back and the settings of TX READY feature veriﬁed will be set to disabled all zero if the settings are invalid The threshold when TX_READY is asserted should not be set above...

Страница 33: ...s entirely on the receiver Table 17 below contains an overview of the diﬀerent MGA services u blox provides Requirements AssistNow Online AssistNow Oﬄine AssistNow Autonomous Requires external ﬂash memory No Optional Optional Requires internet connection Permanently Sporadically No Amount of internet data Medium High None Ephemeris in data Yes No No Almanac in data Yes Yes Yes Table 17 AssistNow s...

Страница 34: ...tter data is available Using these estimates will not provide as accurate a position ﬁx as if current ephemeris data is used but it will allow much faster TTFFs in nearly all cases The data obtained from the AssistNow Oﬄine Service is organized by date normally a day at a time Consequently the longer time for which coverage is requested the larger the amount of data to handle Similarly each diﬀere...

Страница 35: ...XX gnss gps glo 3 9 3 2 Time position and almanac While AssistNow Oﬄine can be used on its own it is expected that the user will provide estimates of the receiver s current position the current time and ensure that a reasonably up to date almanac is available In most cases this information is likely to be available without the user needing to do anything For example where the receiver is connected...

Страница 36: ... whole process The above three steps are repeated until all the rest of the data has been successfully transferred or the process has been aborted The host sends a UBX MGA FLASH STOP message to indicate completion of the upload It awaits the ﬁnal UBX MGA FLASH ACK message in reply Background processing in the receiver prepares the downloaded data for use at this stage Particularly if the receiver ...

Страница 37: ...h AssistNow Oﬄine data looking for entries with a date stamp that most closely matches the current UTC time date The host sends each such UBX MGA ANO message to the receiver Note that when data has been downloaded from the AssistNow Oﬄine service with the default resolution of one day the means for selecting the closest matching date stamp is simply to look for ones with the current UTC date 3 9 4...

Страница 38: ...y generates the required parts of the orbits suitable for navigation from the stored data The data is also automatically kept current in order to minimize the calculation time once the navigation engine needs orbits The operation of the AssistNow Autonomous feature is transparent to the user and the operation of the receiver All calculations are done in the background and do not aﬀect the normal o...

Страница 39: ...usly collected satellite observation data from the ﬂash memory The UBX NAV AOPSTATUS message provides information on the current state of the AssistNow Autonomous subsystem The status indicates whether the AssistNow Autonomous subsystem is currently idle or not enabled or busy generating data or orbits Hosts should monitor this information and only power oﬀ the receiver when the subsystem is idle ...

Страница 40: ...various factors such as the satellite position accuracy the number of visible satellites and the geometry DOP of the visible satellites Position ﬁxes that include AssistNow Autonomous orbit information may be signiﬁcantly worse than ﬁxes using only broadcast ephemerides It might be necessary to adjust the limits of the navigation output ﬁlters CFG NAV OUTFIL_XXXX A fundamental deﬁciency of any sys...

Страница 41: ...rtup is automatically done if the corresponding data is present in the ﬂash Data expiration is not checked The following outlines the suggested shutdown procedure when using the save on shutdown feature With the UBX CFG RST message the host commands the u blox receiver to stop specifying reset mode 0x08 Controlled GNSS stop and a BBR mask of 0 Hotstart The host commands the saving of the contents ...

Страница 42: ...up some all of its internal components according to predeﬁned parameters It is also referred to as power save mode PSM In PSM one of two modes of operations can be selected 1 On oﬀ operation PSMOO 2 Cyclic tracking PSMCT Continuous operation Cyclic operation On oﬀ operation Main use Continuous position tracking Low power continuous position tracking Occasional position tracking Possible applicatio...

Страница 43: ...is means that entering all power saving states is delayed until the conditions necessary to produce a time pulse have been met Therefore in order to obtain good power save mode operation it is essential that any time pulse is correctly conﬁgured with an appropriate time base or that time pulses are turned oﬀ if not needed by disabling the TPX_ENA item in the CFG TP group 3 11 2 1 Operation Power s...

Страница 44: ... as Acquisition timeout Internal mechanisms If the receiver is able to acquire weak signals but not of the quality needed to get a ﬁx it will transition to Inactive awaiting next search state after the timeout conﬁgured in MAXACQTIME or earlier if too few signals are acquired If the receiver is unable to acquire any signals or it acquires a small number of extremely bad signals e g no sky view it ...

Страница 45: ...fter the conﬁgured search period minus a start up margin As soon as the receiver gets a valid position ﬁx one passing the navigation output ﬁlters it enters Tracking state Upon entering Tracking state the ONTIME starts Once the ONTIME is over Inactive awaiting next fix state is entered and the receiver re starts according to the conﬁgured update grid see section Grid oﬀset for an explanation If th...

Страница 46: ...s working in on oﬀ or cyclic tracking operation Therefore it has to temporarily switch to continuous operation for the time the satellites transmit the desired data To save power the receiver schedules the downloads according to an internal timetable and only switches to continuous operation while data of interest is being transmitted by the satellites Each satellite transmits its own ephemeris da...

Страница 47: ... more information on the two modes of operation 3 11 2 2 2 Reference time standard Where multiple GNSS can operate simultaneously UTC time standard is used for the operation of PSM 3 11 2 2 3 Update period POSUPDATEPERIOD and search period ACQPERIOD The update period speciﬁes the time between successive position ﬁxes If no position ﬁx can be obtained within the acquisition timeout the receiver wil...

Страница 48: ...determine the maximum time to spend in Acquisition state Note that shorter settings below about 45 s will degrade an unaided receiver s ability to collect new Ephemeris data at low signal levels see section Satellite data download 3 11 2 2 8 Do not enter Inactive awaiting next search state when no ﬁx DONOTENTEROFF If this option is enabled the receiver acts diﬀerently in case it cannot get a ﬁx in...

Страница 49: ...te is suﬃcient to the receiver s UART interface This will wake up the receiver if it is in Inactive state If the receiver is not in Inactive state the sequence will be ignored Send the conﬁguration message about half a second after the dummy sequence If the interval between the dummy sequence and the conﬁguration message is too short the receiver may not yet be ready If the interval is too long th...

Страница 50: ...ous is beneﬁcial to the overall power consumption or not 3 11 2 4 Examples 3 11 2 4 1 Use grid oﬀset Scenario Get a position ﬁx once a day at a ﬁxed time If the position ﬁx cannot be obtained try again every two hours Solution First set the update period POSUPDATEPERIOD to 24 3600s and the search period ACQPERIOD to 2 3600s Now a position ﬁx is obtained every 24 hours and if the position ﬁx fails ...

Страница 51: ...to produce position ﬁxes it can switch from cyclic operation to on oﬀ operation if this is not disabled with the DONOTENTEROFF switch in CFG PM In that case the remarks below are relevant On oﬀ operation When in state Acquisition the measurement and navigation rate is ﬁxed to 2 Hz All NMEA and UBX messages that are output upon a navigation ﬁx are also output with a rate of 2 Hz This must be consid...

Страница 52: ...the results is an accurate measurement of time in the time base of the chosen GNSS system called GNSS system time The diﬀerence between the calculated GNSS system time and receiver local time is called clock bias and clock drift is the rate at which this bias is changing In practice the receiver s local oscillator will not be as stable as the atomic clocks to which GNSS systems are referenced and ...

Страница 53: ...t GNSS receivers use this representation internally only converting to a more conventional form at external interfaces The iTOW ﬁeld is the most obvious externally visible consequence of this internal representation If reliable absolute time information is required users are recommended to use the UBX NAV PVT navigation solution message which also contains additional ﬁelds that indicate the validi...

Страница 54: ...edth of a second remains so the extra digit is always 0 UTC time is also reported within some UBX messages such as UBX NAV TIMEUTC and UBX NAV PVT In these messages date and time are separated into seven distinct integer ﬁelds Six of these year month day hour min and sec have fairly obvious meanings and are all guaranteed to match the corresponding values in NMEA messages generated by the same nav...

Страница 55: ... about the current time within their data message In most cases this is a time of week often abbreviated to TOW which indicates the elapsed number of seconds since the start of the week midnight Saturday Sunday In order to map this to a full date it is necessary to know the week and so the GNSS also transmit a week number typically every 30 seconds Unfortunately the GPS L1C A data message was desi...

Страница 56: ...547 calendar year 2019 2028 It is important to set the reference rollover week number appropriately when supplying u blox receivers with simulated signals especially when the scenarios are in the past 3 13 Timing functionality In addition to positioning and navigation applications GNSS signals are widely used as low cost precision time or frequency references used by remote or distributed wireless...

Страница 57: ...cable delay and user delay The recommended conﬁguration when using the UBX TIM TP message is to set both the measurement rate CFG RATE MEAS and the time pulse frequency CFG TP to 1 Hz Since the rate of UBX TIM TP is bound to 1 Hz more than one UBX TIM TP message can appear between two pulses if the time pulse frequency is set larger than 1 Hz In this case all UBX TIM TP messages in between time pu...

Страница 58: ...red to use a variant of UTC time after a cold start substantial delays before the receiver has suﬃcient information to start outputting the time pulse can be expected 3 13 1 4 Time pulse conﬁguration u blox NEO M9N receivers provide a time pulse TIMEPULSE signal with a conﬁgurable pulse period length and polarity rising or falling edge It is possible to deﬁne diﬀerent signal behavior i e output fr...

Страница 59: ...ime is not locked or to indicate a lock with diﬀerent duty cycles align to TOW If this item is set pulses are aligned to the top of a second polarity If set the ﬁrst edge of the pulse is a rising edge pulse polarity rising grid UTC GNSS Selection between UTC 0 GPS 1 GLONASS 2 BeiDou 3 and 4 Galileo timegrid Also aﬀects the time output by UBX TIM TP message The maximum pulse length cannot exceed th...

Страница 60: ...P are also applied to the results output in the UBX TIM TM2 message A UBX TIM TM2 message is output at the next epoch if The UBX TIM TM2 message is enabled and A rising or falling edge was triggered since last epoch on one of the EXTINT channels The UBX TIM TM2 messages includes the time of the last timemark new rising falling edge indicator time source validity number of marks and an accuracy est...

Страница 61: ...view about possible threads and which functionality is available to detect and or mitigate it Threat u blox solution Over air signal integrity Spooﬁng detection monitoring Jamming interference detection monitoring GNSS receiver integrity Secure boot Secure ﬁrmware update Receiver conﬁguration lock Table 22 u blox security options 3 14 1 Spooﬁng detection monitoring Spooﬁng is the process where a c...

Страница 62: ...pendent of the CW only jamming indicator described in Jamming interference indicator above This monitor reports whether jamming has been detected or suspected by the receiver The receiver monitors the background noise and looks for signiﬁcant changes Normally with no interference detected it will report OK If the receiver detects that the noise has risen above a preset threshold the receiver repor...

Страница 63: ... a conﬁguration layer in volatile memory RAM BBR is removed when the memory is cleared However the conﬁguration lock set in non volatile memory ﬂash memory is permanent apart from one exception during ﬁrmware upload to ﬂash memory the ﬂash is erased during the process causing the conﬁguration lock to be cleared Refer to Firmware upload for more information on ﬁrmware update To test the lock functi...

Страница 64: ...arity checks have passed Where the parity checking algorithm requires data to be inverted before it is decoded e g GPS L1C A the receiver carries this out before the message output Therefore users can process data directly and do not need to worry about repeating any parity processing The meaning of the content of each subframe depends on the sending GNSS and is described in the relevant interface...

Страница 65: ...u data words only comprise 30 bits the 2 most signiﬁcant bits in each word reported by UBX RXM SFRBX are padding and should be ignored 3 15 1 5 Galileo u blox M9 receivers running can receive and track the E1 B C signals centered on the GPS L1 frequency band GPS and Galileo signals can be processed concurrently together with BeiDou and GLONASS signals enhancing coverage reliability and accuracy Th...

Страница 66: ... subframe contains a pair of I NAV pages as described in the Galileo ICD Galileo pages can either be Nominal or Alert pages For Galileo Nominal pages the eight words are arranged as follows Figure 28 Galileo E1 B subframe words UBX 19014286 R07 3 Receiver functionality Page 66 of 95 C1 Public ...

Страница 67: ...wing table gives a summary of the diﬀerent data message formats reported by the UBX RXM SFRBX message GNSS Signal gnssId sigId numWords period GPS L1C A 0 0 10 6s Galileo E1 B 2 1 8 2s BeiDou B1I D1 3 0 10 6s BeiDou B1I D2 3 1 10 0 6s QZSS L1C A 5 0 10 6s GLONASS L1OF 6 0 3 2s Table 24 Data message formats reported by UBX RXM SFRBX 3 16 Forcing a receiver reset Typically in GNSS receivers a distin...

Страница 68: ... RST message oﬀers the navBbrMask ﬁeld where hot warm and cold starts can be initiated and also other combinations thereof The reset type can also be speciﬁed This is not related to GNSS but to the way the software restarts the system Hardware reset uses the on chip watchdog in order to electrically reset the chip This is an immediate asynchronous reset No Stop events are generated Controlled soft...

Страница 69: ...n no Name I O Description 1 SAFEBOOT_N I SAFEBOOT_N used for FW updates and reconﬁguration leave open 2 D_SEL I Interface select open or VCC UART I2C GND SPI 3 TIMEPULSE O TIMEPULSE 1 PPS 4 EXTINT I EXTINT PIO 7 5 USB_DM I O USB data DM 6 USB_DP I O USB data DP 7 V_USB I USB supply 8 RESET_N I RESET active low 9 VCC_RF O Voltage for external LNA 10 GND I Ground 11 RF_IN I GNSS signal input 12 GND ...

Страница 70: ... M9N modules must charge the internal capacitors in the core domain In certain situations this can result in a signiﬁcant current draw For low power applications using backup mode it is important that the power supply or low ESR capacitors at the module input can deliver this current charge To reduce peak current during power on users can employ an LDO that has an in built current limiter Do not a...

Страница 71: ... is handled with software commands See the NEO M9N Interface description 2 for more information 4 2 3 V_USB USB interface power supply V_USB supplies the USB interface If the USB interface is not used the V_USB pin must be connected to GND For more information about correctly handling the V_USB pin see Interfaces section 4 3 NEO M9N minimal design The minimal electrical circuit for NEO M9N operati...

Страница 72: ...ble hot starts the time information must be provided accurately and thus the time mark feature must be used The time aiding and time mark features are described in the NEO M9N Interface description 2 Time aiding cannot be applied when using the power save mode operations because the host does not have any information when the GNSS receiver turns from OFF status to ON status during on oﬀ operation ...

Страница 73: ... interfere with the antenna performance The antenna must have suﬃcient bandwidth to receive all needed GNSS constellations Also the antenna should have a suitable ground plane to achieve good performance Passive antennas do not require a DC bias voltage and can be directly connected to the RF input pin RF_IN The example circuit in Figure 32 shows a setup for a design with a good passive GNSS anten...

Страница 74: ... active antenna module meeting u blox s speciﬁcation A suitable ground plane is required for the antenna to achieve good performance Active antenna may have strong gain For maximum external gain see the Data sheet 1 in Related documents A series current limiting resistor is required to prevent short circuits destroying the bias t inductor If the VCC_RF voltage of the NEO M9N module does not match ...

Страница 75: ...However a signiﬁcant violation may reduce receiver sensitivity or cause a complete loss of signal reception The severity of the interference depends on the repetition rate frequency signal level modulation and bandwidth of the signal Figure 34 shows a typical out of band immunity level for the NEO M9N RF input The measurement is done at room temperature using a continuous wave CW test signal The i...

Страница 76: ...charge ESD Special precautions are required when handling Most defects caused by ESD can be prevented by following strict ESD protection rules for production and handling When implementing passive antenna patches or external antenna connection points then additional ESD measures as shown in the ﬁgure below can also avoid failures in the ﬁeld Figure 35 RF ESD precautions 4 6 2 EOS precautions Elect...

Страница 77: ...o the GNSS antenna EMI protection measures are particularly useful when RF emitting devices are placed next to the GNSS receiver and or to minimize the risk of EMI degradation due to self jamming An adequate layout with a robust grounding concept is essential in order to protect against EMI Intended Use In order to mitigate any performance degradation of a radio equipment under EMC disturbance sys...

Страница 78: ...anteed even under interference conditions In such a case not only the maximum power ratings of the components in the receiver RF path must be observed Further non linear eﬀects like gain compression NF degradation desensitization and intermodulation must be analyzed Pulsed interference with a low duty cycle such as GSM may be destructive due to the high peak power levels 4 7 2 In band interference...

Страница 79: ...l circuits on the board A proper GND concept shall be followed The RF section shall not be subject to noisy digital supply currents running through its GND plane 4 8 2 Thermal management During design in do not place the receiver near sources of heating or cooling The receiver oscillator is sensitive to sudden changes in ambient temperature which can adversely impact satellite signal tracking Sour...

Страница 80: ...NEO M9N Integration manual 4 8 3 1 Mechanical dimensions Figure 37 NEO M9N mechanical dimensions UBX 19014286 R07 4 Design Page 80 of 95 C1 Public ...

Страница 81: ...uces the risk of performance issues at design level 4 8 4 1 RF In trace The RF In trace has to work in the middle L band frequencies A grounded co planar RF trace is recommended as it provides the maximum shielding from noise with adequate vias to the ground layer Focus on these layout guidelines RF input co planar caveguide referenced to layer 2 matched to 50 Ω UBX 19014286 R07 4 Design Page 81 o...

Страница 82: ...on the top layer should be referenced to a suitable ground layer 4 8 4 2 VCC pad The VCC pad for the NEO M9N module needs to have as low an impedance as possible with large vias to the lower power layer of the PCB The VCC pad needs a large pad and the decoupling capacitor must be placed as close as possible This is shown in the ﬁgure below Figure 41 VCC pad 4 9 Design guidance 4 9 1 General consid...

Страница 83: ...ected with VCC removed 4 9 3 RF front end circuit options The ﬁrst stages of the signal processing chain are crucial to the overall receiver performance When an RF input connector is employed this can provide a conduction path for harmful or destructive electrical signals If this is a likely factor the RF input should be protected accordingly Additional points on the RF input What is the expected ...

Страница 84: ... a minimal design with the NEO M9N GNSS modules consider the following functions and pins Connect the power supply to VCC and V_BCKP V_USB If USB is used it is recommended V_USB is to be powered as per USB self powered mode speciﬁcation If USB is not used connect V_USB to ground Ensure an optimal ground connection to all ground pins of the NEO M9N GNSS module Choose the required serial communicati...

Страница 85: ... antenna area is touched in non ESD protected work area implement proper ESD protection measures in the design When soldering RF connectors and patch antennas to the receiver s RF pin make sure to use an ESD safe soldering iron tip 5 2 Soldering Soldering paste Use of no clean soldering paste is highly recommended as it does not require cleaning after the soldering process The paste in the example...

Страница 86: ...rature rises above the liquidus temperature of 217 C Avoid a sudden rise in temperature as the slump of the paste could become worse Limit time above 217 C liquidus temperature 40 60 s Peak reﬂow temperature 245 C Cooling phase A controlled cooling prevents negative metallurgical eﬀects of the solder solder becomes more brittle and possible mechanical tensions in the products Controlled cooling he...

Страница 87: ...for a single ﬁnal upright reﬂow cycle A module placed on the underside of the board may detach during a reﬂow soldering cycle due to lack of adhesion The module can also tolerate an additional reﬂow cycle for re work purposes Wave soldering Base boards with combined through hole technology THT components and surface mount technology SMT devices require wave soldering to solder the THT components O...

Страница 88: ... of metal strips directly onto the EMI covers Use of ultrasonic processes Some components on the module are sensitive to ultrasonic waves Use of any ultrasonic processes cleaning welding etc may cause damage to the GNSS receiver u blox oﬀers no warranty against damages to the module caused by ultrasonic processes 5 3 Packaging The NEO M9N modules are delivered as hermetically sealed reeled tapes i...

Страница 89: ...n Guide 4 5 6 Moisture sensitivity levels The moisture sensitivity level MSL for NEO M9N is speciﬁed in the table below Package MSL level LCC 4 Table 27 MSL level For MSL standard see IPC JEDEC J STD 020 which can be downloaded from www jedec org For more information regarding moisture sensitivity levels labeling storage and drying see the u blox Package Information Guide 4 UBX 19014286 R07 5 Prod...

Страница 90: ...s Ensure that the power supply is still able to provide clean and stable voltage with the higher current demand in NEO M9N Pin out 1 1 pin out mapping with NEO 8Q M8N Q J M modules NEO M8M pin 14 is reserved and NEO M9N pin 14 is LNA_EN NEO M8M designs can be updated to use pin 14 on NEO M9N for external LNA and antenna control VDD_USB pin 7 name changed to V_USB in NEO M9N to agree with a common ...

Страница 91: ...ources in the design Code change optional Time pulse The quantization error output via UBX TIM TP2 is no longer supported u blox recommends using dedicated timing products for precise time information Code change NMEA Supports NMEA 0183 V4 10 V4 0 V2 3 and V2 1 NMEA V4 10 is enabled by default Code change optional RTCM RTCM 3 3 is supported RTCM 2 3 is not supported Code change Power save modes PS...

Страница 92: ...ectromagnetic interference EOS Electrical overstress EPA Electrostatic protective area ESD Electrostatic discharge Galileo European navigation satellite system GLONASS Russian navigation satellite system GND Ground GNSS Global navigation satellite system GPS Global Positioning System GSM Global System for Mobile Communications I2C Inter integrated circuit bus IEC International Electrotechnical Com...

Страница 93: ...ce description UBX 21022437 NDA required 3 u blox M9 SPG 4 04 Release notes UBX 20036165 4 Packaging information for u blox chips modules and antennas UBX 14001652 For regular updates to u blox documentation and to receive product change notiﬁcations please register on our homepage https www u blox com UBX 19014286 R07 Related documents Page 93 of 95 C1 Public ...

Страница 94: ...section 3 1 5 RTCM corrections Removed old section 4 3 4 NEO M9N power supply Updated description of 50 Ω matching in section 4 5 Antenna R05 11 Sep 2020 jesk Early production information Updated ﬁrmware version to 4 04 Changed topic title to Weak signal compensation in section 3 1 7 6 Clariﬁed I2C addressing in section 3 5 2 Changed AssistNow Autonomous default setting in section 3 7 6 1 R06 08 J...

Страница 95: ...s u blox com E mail info_cn u blox com Support support_cn u blox com Regional Oﬃce China Chongqing Phone 86 23 6815 1588 E mail info_cn u blox com Support support_cn u blox com Regional Oﬃce China Shanghai Phone 86 21 6090 4832 E mail info_cn u blox com Support support_cn u blox com Regional Oﬃce China Shenzhen Phone 86 755 8627 1083 E mail info_cn u blox com Support support_cn u blox com Regional...

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