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RCB-F9T - Integration manual

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
is invalidated. 

Table 10

 above shows the types of sanity checks which are applied for a particular

dynamic platform model.

3.1.8.2 Navigation input filters

The  navigation  input  filters  in  CFG-NAVSPG-*  configuration  group  provide  the  input  data  of  the
navigation engine.

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 in order 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_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 11: 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.

3.1.8.3 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
(e.g. 2D, 3D, dead reckoning).

The RCB-F9T firmware does not support the dead reckoning position fix type.

Where a fix has been achieved, a check is made to determine whether the fix should be classified as
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 valid should not be used.

UBX-NAV-STATUS message also reports whether a fix is valid in the 

gpsFixOK

 flag. This message

has only been retained for backwards compatibility and users are recommended to use the UBX-
NAV-PVT message.

3.1.8.3.1 Speed (3D) low-pass filter

The CFG-ODO-OUTLPVEL configuration item offers the possibility to activate a speed (3D) low-pass
filter. The output of the speed low-pass filter is published in the UBX-NAV-VELNED message (

speed

field). The filtering level can be set via the CFG-ODO-VELLPGAIN configuration item and must be
comprised between 0 (heavy low-pass filtering) and 255 (weak low-pass filtering).

UBX-22004121 - R01

 

3 Receiver functionality

Page 16 of 64

C1-Public

Early production information

Содержание RCB-F9T

Страница 1: ...accuracy timing board Integration manual Abstract This document describes the features and application of RCB F9T a multi band GNSS timing board o ering nanosecond level timing accuracy www u blox co...

Страница 2: ...ghts in the products names logos and designs included in this document Copying reproduction modi cation or disclosure to third parties of this document or any part thereof is only permitted with the e...

Страница 3: ...21 3 3 3 Geofence state evaluation 21 3 4 Logging 22 3 4 1 Introduction 22 3 4 2 Setting the logging system up 22 3 4 3 Information about the log 23 3 4 4 Recording 23 3 4 5 Retrieval 25 3 4 6 Command...

Страница 4: ...er 49 3 12 4 Sky view signal masking 50 3 13 Forcing a receiver reset 51 3 14 Firmware upload 52 4 Design 53 4 1 Pin assignment 53 4 2 Power supply 53 4 2 1 VCC Main supply voltage 53 4 2 2 RCB F9T VC...

Страница 5: ...ormation on all aspects of RCB F9T 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 produc...

Страница 6: ...its di erential timing mode In di erential timing mode correction data is exchanged with other neighboring RCB F9T timing receivers via a communication network In di erential timing mode the RCB F9T c...

Страница 7: ...oup name CFG GROUP a convention used in u center and within this document Within u center a con guration group is identi ed as Group name and the con guration item is identi ed as the item name under...

Страница 8: ...the various communication interfaces These include parameters for the data framing transfer rate and enabled input output protocols The con guration groups available for each interface are Interface C...

Страница 9: ...igh precision position 3 1 5 Di erential timing mode con guration In di erential timing mode the RCB F9T can operate either as a master reference station or as a slave station Using the RTCM3 protocol...

Страница 10: ...urvey in Survey in is a procedure that is carried out prior to entering Time mode It estimates the receiver position by building a weighted mean of all valid 3D position solutions Two major parameters...

Страница 11: ...HT_HP High precision height of the ARP position coordinate in 0 1 millimeters CFG TMODE FIXED_POS_ACC Fixed position 3D accuracy estimate Table 6 Con guration items used for setting a timing receiver...

Страница 12: ...ion When the RCB F9T acts as a slave receiver it receives di erential corrections RTCM 3 3 messages from a master reference station and aligns its time pulse to it Connect the slave receiver to the re...

Страница 13: ...output message Table 8 Example secondary output con guration items Enabling the secondary output The rst necessary step to enable the secondary output is to con gure the CFG NAV2 OUT_ENABLED con gurat...

Страница 14: ...X NAV EOE or a UBX NAV2 EOE message respectively In other words a UBX NAV EOE message will be output at the end of the UBX NAV class enabled messages and a UBX NAV2 EOE message will be output at the e...

Страница 15: ...ty 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 equi...

Страница 16: ...satellite When a satellite is lost after a successful 3D x min four satellites available the altitude is kept constant at the last known value This is called a 2D x u blox receivers do not calculate a...

Страница 17: ...r ground lter is published in the UBX NAV PVT message headMot eld UBX NAV VELNED message heading eld NMEA RMC message cog eld and NMEA VTG message cogt eld If the low speed course over ground lter is...

Страница 18: ...Integration manual Figure 2 Position publication in static hold mode Figure 3 Flowchart of the static hold mode UBX 22004121 R01 3 Receiver functionality Page 18 of 64 C1 Public Early production info...

Страница 19: ...owing section describes the receiver operation when SBAS reception is required by users The RCB F9T is capable of receiving multiple SBAS signals concurrently even from di erent SBAS systems WAAS EGNO...

Страница 20: ...orth America In the 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...

Страница 21: ...s surface The receiver will then evaluate for each of these areas whether the current position lies within the area or not and signal the state via UBX messaging and PIO toggling 3 3 2 Interface Geof...

Страница 22: ...OG RETRIEVESTRING A byte string log entry returned by the receiver UBX LOG FINDTIME Finds the index of the rst entry given time Table 15 Logging retrieval messages 3 4 2 Setting the logging system up...

Страница 23: ...ther three bytes per x Each log also has a xed overhead which is dependent on the log type The approximate size of this overhead is shown in the following table Log type Overhead circular Up to 40 kB...

Страница 24: ...t point on earth or higher than 20 000 m may not be recorded in the log Ground speed to a precision of 1 cm s The x type only successful x types since these are the only ones recorded The number of sa...

Страница 25: ...ia CFG_LOGFILTER RECORD_ENA while retrieving log entries from a circular log to avoid deletion of the requested entries between the request and transmission The receiver will send a UBX LOG RETRIEVEPO...

Страница 26: ...ortId Electrical interface 1 0x0100 UART1 Table 17 Port number assignment It is important to isolate interface pins when the RCB F9T VCC is removed They can be allowed to oat or connected to a high im...

Страница 27: ...supervisor can also be checked by polling the related CFG HW_ANT_ con guration items The current active antenna status can be determined by polling the UBX MON RF message If an antenna is connected t...

Страница 28: ...CB F9T Start up message at power up if con guration is stored GNTXT 01 01 02 ANTSUPERV AC SD PDoS SR 3E GNTXT 01 01 02 ANTSTATUS INIT 3B GNTXT 01 01 02 ANTSTATUS OK 25 ANTSUPERV AC SD PDoS SR SR indic...

Страница 29: ...y modi cation 3 8 1 Authorization To use the AssistNow services customers will need to obtain an authorization token from u blox Go to https www u blox com en solution services assistnow or contact yo...

Страница 30: ...n accurate measurement of time in the time base of the chosen GNSS system called GNSS system time The di erence between the calculated GNSS system time and receiver local time is called clock bias and...

Страница 31: ...s use this representation internally only converting to a more conventional form at external interfaces The iTOW eld is the most obvious externally visible consequence of this internal representation...

Страница 32: ...ar 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 navigation epoch This facilitates simple sync...

Страница 33: ...he 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 Sund...

Страница 34: ...028 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 10 Timing functionali...

Страница 35: ...more than one UBX TIM TP message can appear between two pulses if the time pulse frequency is set lower than 1 Hz In this case all UBX TIM TP messages in between time pulses T1 and T2 belong to T2 an...

Страница 36: ...efore if a time pulse is con gured to use a variant of UTC time after a cold start substantial delays before the receiver has su cient information to start outputting the time pulse can be expected 3...

Страница 37: ...em is set pulses are aligned to the top of a second polarity If set the rst 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...

Страница 38: ...nal parameters for suspicious changes to identify external manipulation A ag in UBX NAV STATUS message ags2 spoofDetState alerts the user to potential spoo ng activity A detection is successful when a...

Страница 39: ...ge it is also possible to specify the thresholds at which broadband and CW jamming are reported These thresholds should be interpreted as the dB level above normal It is also possible to specify wheth...

Страница 40: ...indicate the structure Because of this the following sections are organized by GNSS However in some cases the identity of the GNSS is not su cient and this is described where appropriate in the follow...

Страница 41: ...e as described in the GPS ICD The ten words are arranged as follows Figure 13 GPS L2C subframe words 3 12 1 2 3 GPS L5 For GPS L5 signals each reported subframe contains the CNAV message as described...

Страница 42: ...dle chip which should always have a value of zero The meaning of other bits varies with string and frame number The fourth and nal 32 bit word in the UBX RXM SFRBX message contains frame and superfram...

Страница 43: ...BeiDou ICD Each subframe comprises ten data words which are reported in the same order they are received Each word is arranged as follows Figure 16 BeiDou subframe word Note that as the BeiDou data w...

Страница 44: ...and F NAV message respectively The UBX RXM SFRBX structure for the I NAV and F NAV messages are shown below 3 12 1 5 1 Galileo E1 B For the Galileo E1 B signal each reported subframe contains a pair o...

Страница 45: ...ages are reported in very similar manner but the page type bits will have value 1 and the structure of the eight words will be slightly di erent as indicated by the Galileo ICD UBX 22004121 R01 3 Rece...

Страница 46: ...subframe contains a pair of I NAV pages as described in the Galileo ICD Galileo pages can either be Nominal or Alert pages For Nominal pages the eight words are arranged as follows Figure 18 Galileo...

Страница 47: ...ICD For each page the eight words are arranged as follows Figure 19 Galileo E5a subframe words 3 12 1 6 SBAS For SBAS L1C A signals each reported subframe contains eight 32 bit data words to deliver...

Страница 48: ...ta message formats reported by the UBX RXM SFRBX message GNSS Signal gnssId sigId numWords period GPS L1C A 0 0 10 6s GPS L2CL 0 3 10 12s GPS L2CM 0 4 10 12s GPS L5 I 0 6 10 6s SBAS L1C A 1 0 9 1s Gal...

Страница 49: ...detects the previously stored data in the ash It restores the corresponding memory and reports the success of the operation with a UBX UPD SOS RESTORED message on the port on which it had received the...

Страница 50: ...1 Spectrum analyzer view in u center with the option view hold selected The span frequency depends on the number of constellations enabled which impacts the spectrum resolution owing to a xed set of p...

Страница 51: ...to download ephemeris before it can calculate position and velocity data As the ephemeris data usually is outdated after 4 hours the receiver will typically start with a warm start if it has been pow...

Страница 52: ...omers implement a rmware update mechanism in their system A rmware image is a binary le containing the software to be run by the GNSS receiver A rmware update is the process of transferring a rmware i...

Страница 53: ...t 5 RXD I UART RXD LVCMOS 6 TP1 O Time pulse1 LVCMOS 7 TP2 O Time pulse2 LVCMOS 8 GND Ground Table 22 RCB F9T pin assignment See Figure 26 for a detailed view of the board measurements The labelling o...

Страница 54: ...tive antenna powering If active antenna powering is not needed then the VCC_ANT can be left to unconnected 4 3 Antenna The RCB F9T requires an active antenna with integral LNA to ensure good performan...

Страница 55: ...o observe strict EOS ESD EMI handling and protection measures To prevent overstress damage at the RF_IN of your receiver never exceed the maximum input power as speci ed in the applicable data sheet 1...

Страница 56: ...um speci ed ratings EOS failure can happen if RF emitters are close to a GNSS receiver or its antenna EOS causes damage to the chip structures If the RF_IN is damaged by EOS it is hard to determine wh...

Страница 57: ...ty to the GNSS receiving antenna especially if such a system is integrated with the GNSS receiver Even at reasonable antenna selectivity destructive power levels may reach the RF input of the GNSS rec...

Страница 58: ...interference include maintaining a good grounding concept in the design and adding a GNSS band pass lter into the antenna input line to the receiver For GSM applications such as typical handset design...

Страница 59: ...n antenna patch connect ground of the device When handling the RF pin do not come into contact with any charged capacitors and be careful when contacting materials that can develop charges e g patch a...

Страница 60: ...24 RCB F9T speci c UART baud rate antenna supervisor and time pulse 1 default con gurations B Glossary Abbreviation De nition ANSI American National Standards Institute ARP Antenna reference point Bei...

Страница 61: ...m SV Space vehicle a satellite UBX u blox C RCB F9T PCB dimensions The RCB F9T pcb dimensions are shown below in Figure 26 to provide accurate mounting and antenna connector alignment information Figu...

Страница 62: ...ace description UBX 21048598 3 Radio Resource LCS Protocol RRLP 3GPP TS 44 031 version 11 0 0 Release 11 For regular updates to u blox documentation and to receive product change noti cations please r...

Страница 63: ...vision history Revision Date Name Status comments R01 28 Mar 2022 byou Combined integration manual issued for RCB F9T 0 and RCB F9T 1 variants UBX 22004121 R01 Revision history Page 63 of 64 C1 Public...

Страница 64: ...ail info_cn u blox com Support support_cn u blox com Regional O ce China Chongqing Phone 86 23 6815 1588 E mail info_cn u blox com Support support_cn u blox com Regional O ce China Shanghai Phone 86 2...

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