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Ublox RCB-F9T Integration Manual

Ublox RCB-F9T Integration Manual

High accuracy timing board
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RCB-F9T
u-blox RCB-F9T high accuracy timing board
Integration manual
Abstract
This document describes the features and application of RCB-F9T, a multi-
band GNSS timing board offering nanosecond-level timing accuracy.
www.u-blox.com
UBX-22004121 - R01
C1-Public

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  • Page 1  RCB-F9T u-blox RCB-F9T high accuracy timing board Integration manual Abstract This document describes the features and application of RCB-F9T, a multi- band GNSS timing board offering nanosecond-level timing accuracy. www.u-blox.com UBX-22004121 - R01 C1-Public...
  • Page 2 RCB-F9T - Integration manual Document information Title RCB-F9T Subtitle u-blox RCB-F9T high accuracy timing board Document type Integration manual Document number UBX-22004121 Revision and date 28-Mar-2022 Document status Early production information Disclosure restriction C1-Public This document applies to the following products: Type number...

  • Page 3: Table Of Contents

    RCB-F9T - Integration manual Contents 1 Integration manual overview..................... 5 2 System description.......................6 2.1 Overview..............................6 2.1.1 Differential timing.......................... 6 2.2 Architecture..............................6 2.2.1 Block diagram..........................6 3 Receiver functionality......................7 3.1 Receiver configuration........................... 7 3.1.1 Changing the receiver configuration..................7 3.1.2 Default GNSS configuration......................7 3.1.3 Default interface settings......................
  • Page 4 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 VCC_ANT: Antenna power supply................54 4.3 Antenna..............................54 4.4 EOS/ESD precautions.......................... 55 4.4.1 ESD protection measures......................56 4.4.2 EOS precautions...........................56 4.4.3 Safety precautions........................

  • Page 5: Integration Manual Overview

    RCB-F9T - Integration manual 1 Integration manual overview This document is an important source of information 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 product.

  • Page 6: System Description

    2.1.1 Differential timing The u-blox RCB-F9T high accuracy timing board takes local timing accuracy to the next level with its differential timing mode. In differential timing mode correction data is exchanged with other neighboring RCB-F9T timing receivers via a communication network.

  • Page 7: Receiver Functionality

    This section describes the RCB-F9T operational features and their configuration. 3.1 Receiver configuration The RCB-F9T 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 run-time.

  • Page 8: Default Interface Settings

    RCB-F9T - Integration manual The NavIC L5 signal is supported by the RCB-F9T-1, but not enabled in the default GNSS configuration. SBAS is also supported but not enabled by default as it is not recommended for timing applications. For more information about the default configuration, see the applicable interface description [2].

  • Page 9: Differential Timing Mode Configuration

    3.1.5 Differential timing mode configuration In differential timing mode the RCB-F9T can operate either as a master reference station or as a slave station. Using the RTCM3 protocol, the master sends timing corrections to the slave via a communication link enabling the slave to compute its time relative to the master with high accuracy.
  • Page 10 RTCM 4072.1 Additional reference station information (u-blox proprietary RTCM Message) Table 4: RCB-F9T supported output RTCM version 3.3 messages 3.1.5.4 Timing receiver position Time mode is a special receiver mode where the position of the receiver is known and fixed and only the time and frequency is calculated using all available satellites.
  • Page 11 3.1.5.5 Master reference station When the RCB-F9T high accuracy timing board acts as a master timing station, it sends RTCM 3.3 differential corrections to slave receivers. Corrections are generated after a timing fix calculation in order to remove the master receiver's clock offset.

  • Page 12: Primary And Secondary Output

    Table 7: Configuration items used for setting a master reference station 3.1.5.6 Slave station When the RCB-F9T acts as a slave receiver, it receives differential corrections RTCM 3.3 messages from a master reference station and aligns its time pulse to it.
  • Page 13 By default, the secondary output is disabled. Note that if you do not follow the next step, there will be no secondary output visible in the RCB-F9T communication interfaces in the form of UBX-NAV2- * messages.

  • Page 14: Legacy Configuration Interface Compatibility

    3.1.6.3 Expected output behavior Once the secondary output is enabled and the desired secondary output UBX-NAV2-* messages are configured, the RCB-F9T will output both primary and secondary output data in the form of the enabled UBX-NAV-* and UBX-NAV2-* messages respectively.

  • Page 15: Navigation Configuration

    RCB-F9T - Integration manual See Legacy UBX-CFG message fields reference section in the applicable interface description [2]. 3.1.8 Navigation configuration This section presents various configuration options related to the navigation engine. These options can be configured through various configuration groups, such as CFG-NAVSPG-*, CFG-ODO-*, and CFG-MOT-*.
  • Page 16 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.
  • Page 17 RCB-F9T - Integration manual 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. 3.1.8.3.2 Course over ground low-pass filter The CFG-ODO-OUTLPCOG configuration item offers the possibility to activate a course over ground low-pass filter when the speed is below 8 m/s.
  • Page 18 RCB-F9T - 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 information...

  • Page 19: Sbas

    Figure 4: Flowchart of the course over ground freezing 3.2 SBAS Whilst the RCB-F9T can make use of SBAS satellites, experience has shown that employing these signals can degrade the timing performance and hence SBAS use is not enabled by default. The following section describes the receiver operation when SBAS reception is required by users.
  • Page 20 RCB-F9T - Integration manual interface description [2]). The message UBX-NAV-SBAS provides detailed information about which corrections are available and applied. 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.

  • Page 21: Geofencing

    RCB-F9T - Integration manual 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 5 GPS satellites. If this condition is not met, SBAS integrity data will not be applied.

  • Page 22: Logging

    RCB-F9T - Integration manual Figure 6: Geofence states The combined state for all geofences is evaluated as the combination (Union) of all geofences: • Inside - The position lies inside of at least one geofence • Outside - The position lies outside of all geofences •...

  • Page 23: Information About The Log

    RCB-F9T - Integration manual processed. The logging system will start up automatically on power-up if there is a log in existence. The log will remain in the receiver until specifically erased using the UBX-LOG-ERASE message. The CFG-LOGFILTER-* configuration group controls whether logging of entries is currently enabled and selects position fix messages for logging.
  • Page 24 RCB-F9T - Integration manual 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.

  • Page 25: Retrieval

    RCB-F9T - Integration manual Figure 8: The states of the active logging subsystem 3.4.5 Retrieval UBX-LOG-RETRIEVE starts the process which allows the receiver to output log entries. UBX-LOG- INFO may be helpful to a host system in order to understand the current log status before retrieval is started.

  • Page 26: Communication Interface

    If hardware backup mode is used a proper isolation of the interfaces is needed. 3.6.1 RESET_N The RCB-F9T 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.

  • Page 27: Antenna Supervisor

    3.7 Antenna supervisor The RCB-F9T includes circuitry to check an active antenna connection for open and short circuits and to shut off the antenna supply if a short circuit is detected. The circuitry connects with the...

  • Page 28: Antenna Short Detection Auto Recovery

    Setting the configuration item CFG-HW-ANT_CFG_RECOVER to true (1) enables the antenna short detection auto recovery function. The antenna short detection auto recovery is enabled by default in the RCB-F9T. Start-up message at power up if configuration is stored:- $GNTXT,01,01,02,ANTSUPERV=AC SD PDoS SR*3E...

  • Page 29: Multiple Gnss Assistance (Mga)

    RCB-F9T - Integration manual When enabled if the ANT-DETECT pin is high the antenna is assumed to be connected under nominal current and voltage conditions. Start-up message at power up if configuration is stored: $GNTXT,01,01,02,ANTSUPERV=AC SD OD PDoS SR*15 $GNTXT,01,01,02,ANTSTATUS=INIT*3B $GNTXT,01,01,02,ANTSTATUS=OK*25 ANTSUPERV=AC SD OD PDoS SR (OD indicates open circuit detection enabled)

  • Page 30: Clocks And Time

    RCB-F9T - Integration manual 3.9 Clocks and time This section introduces and explains the concepts of receiver clocks and time bases. 3.9.1 Receiver local time The receiver is dependent on a local oscillator for both the operation of its radio parts and also for timing within its signal processing.

  • Page 31: Itow Timestamps

    RCB-F9T - Integration manual always generated, but they may be wrong by a few seconds (especially shortly after receiver start). Depending on the configuration of the receiver, such "invalid" times may well be output, but with flags indicating their state (e.g. the "valid" flags in UBX-NAV-PVT).

  • Page 32: Utc Representation

    RCB-F9T - Integration manual that the probability of the time to be correct is very high. Note that information about time validity confirmation is only available if the confirmedAvai bit in the UBX-NAV-PVT message is set. validDate means that the receiver has knowledge of the current date. However, it must be noted that this date might be wrong for various reasons.

  • Page 33: Leap Seconds

    RCB-F9T - Integration manual applications. The best timing accuracy and stability is achieved when receiver outputs GNSS time scale rather than UTC. 3.9.7 Leap seconds Occasionally it is decided (by one of the international time keeping bodies) that, due to the slightly uneven spin rate of the Earth, UTC has moved sufficiently out of alignment with mean solar time (i.e.

  • Page 34: Timing Functionality

    RCB-F9T - Integration manual 3.9.9.1 GPS-only date resolution In circumstances where only GPS L1C/A signals are available and for receivers with earlier firmware versions, the receiver establishes the date by assuming that all week numbers must be at least as large as a reference rollover week number. This reference rollover week number is hard-coded at compile time and is normally set a few weeks before the software is completed, but it can be overridden by CFG-NAVSPG-WKNROLLOVER configuration item to any value the user wishes.
  • Page 35 RCB-F9T - Integration manual UTC(USNO), ensure GPS signals are available, and for GLONASS time or UTC(SU) ensure the presence GLONASS signals). This will involve coordinating the setting of CFG-SIGNAL-* configuration group with the choice of time pulse time base. • When using time pulse for timing applications requiring absolute time accuracy, e.g. with requirements specifying offset to UTC, it is recommended to calibrate the user's full setup for...
  • Page 36 3.10.1.4 Time pulse configuration u-blox RCB-F9T 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 frequency and pulse length) depending on whether or not the receiver is locked to a reliable time source.
  • Page 37 50 ns (except when disabling it completely), otherwise pulses can be lost. RCB-F9T time pulse 1 default configuration: UTC time, frequency is 1 Hz and pulse length is 100 ms when GNSS is not locked and 200 ms when GNSS is locked.

  • Page 38: Security

    Figure 11: Time pulse signal with the example parameters 3.11 Security The security concept of RCB-F9T covers the air interface between the receiver and the GNSS satellites and the integrity of the receiver itself. There are functions to monitor/detect certain security threats and report it to the host system.

  • Page 39: Consolidated Signal Security Information

    See the applicable interface description [2]. 3.11.4 GNSS receiver integrity 3.11.4.1 Secure boot The RCB-F9T boots only with firmware images that are signed by u-blox. This prevents the execution of non-genuine firmware images run on the receiver. TIM 2.13,TIM2.20 FW onwards...

  • Page 40: U-Blox Protocol Feature Descriptions

    RCB-F9T - Integration manual 3.11.4.2 Secure firmware update The firmware image itself is encrypted and signed by u-blox. The RCB-F9T verifies the signature at each start. 3.12 u-blox protocol feature descriptions 3.12.1 Broadcast navigation data This section describes the data reported via UBX-RXM-SFRBX.
  • Page 41 RCB-F9T - Integration manual Figure 12: GPS L1C/A subframe word 3.12.1.2.2 GPS L2C For GPS L2C signals each reported subframe contains the CNAV message 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...
  • Page 42 RCB-F9T - Integration manual Figure 14: GPS L5 subframe words 3.12.1.3 GLONASS For GLONASS L1OF signal, the UBX-RXM-SFRBX message contains a string content within the frame structure as described in the GLONASS ICD. This string comprises 85 data bits which are reported over three 32-bit words in the message. Data bits 1 to 8 are always a hamming code, while bits 81 to 84 are a string number and bit 85 is the idle chip, which should always have a value of zero.
  • Page 43 RCB-F9T - Integration manual Figure 15: GLONASS navigation message data In some circumstances, (especially on startup) the receiver may be able to decode data from a GLONASS satellite before it can identify it. When this occurs UBX-RXM-SFRBX messages will be issued with an svId of 255 to indicate "unknown".
  • Page 44 RCB-F9T - Integration manual The Galileo E1-B and E5b in-phase signals (RCB-F9T-0) transmit the I/NAV data message but in different configurations to enhance down-load time for dual frequency receivers. The Galileo E1-B and E5a signals (RCB-F9T-1) transmit the I/NAV and F/NAV message respectively. The UBX-RXM- SFRBX structure for the I/NAV and F/NAV messages are shown below.
  • Page 45 RCB-F9T - Integration manual Figure 17: Galileo E1-B subframe words Alert pages 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 different (as indicated by the Galileo ICD).
  • Page 46 RCB-F9T - Integration manual 3.12.1.5.2 Galileo E5b For the Galileo E5b in-phase signal data component, each reported 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:...
  • Page 47 RCB-F9T - Integration manual 3.12.1.5.3 Galileo E5a For the Galileo E5a in-phase signal data component, each reported subframe contains a number of F/NAV pages as described in the Galileo ICD. For each page the eight words are arranged as follows: Figure 19: Galileo E5a subframe words 3.12.1.6 SBAS...
  • Page 48 RCB-F9T - Integration manual Figure 20: SBAS subframe words 3.12.1.7 QZSS The structure of the data delivered by QZSS L1C/A signals is effectively identical to that of GPS (L1C/A). Similarly the structure of the data delivered by the QZSS L2C and L5 signals are effectively identical to that of GPS L2C and L5 respectively.

  • Page 49: Save-On-Shutdown Feature

    RCB-F9T - Integration manual GNSS Signal gnssId sigId numWords period GLONASS L2OF Table 21: Data message formats reported by UBX-RXM-SFRBX 3.12.2 Save-on-shutdown feature The save-on-shutdown feature (SOS) enables the u-blox receiver to store the contents of the battery-backed RAM to an external flash memory and restore it upon startup. This allows the u- blox receiver to preserve some of the features available only with a battery backup (preserving configuration and satellite orbit knowledge) without having a battery backup supply present.

  • Page 50: Sky View Signal Masking

    RCB-F9T - Integration manual The message is output once per second when enabled. Depending on the receiver type, one or two measurement blocks will be output, indicated by the numRfBlocks flag field. The first block provides L1 spectrum data which can be followed by an L2 or L5 block with multi-band receivers.

  • Page 51: Forcing A Receiver Reset

    RCB-F9T - Integration manual for timing receivers when surveyed into urban locations with a restricted sky view. Customers can e.g. use local mapping data to predict the sky view and set appropriate masking parameters. The CFG-NAVMASK-EL_MASK configuration allows masking of set parts of the sky in increments of nominally 5 deg.

  • Page 52: Firmware Upload

    RCB-F9T - Integration manual 3.14 Firmware upload RCB-F9T is supplied with firmware. u-blox may release updated images containing, for example, security fixes, enhancements, bug fixes, etc. Therefore it is important that customers implement a firmware update mechanism in their system. A firmware image is a binary file containing the software to be run by the GNSS receiver. A firmware update is the process of transferring a firmware image to the receiver and storing it in non-volatile...

  • Page 53: Design

    RCB-F9T - Integration manual 4 Design This section provides information to help carry out a successful RCB-F9T board integration. 4.1 Pin assignment The pin assignment of the RCB-F9T module is shown in Figure 22. The defined configuration of the PIOs is listed in...

  • Page 54: Rcb-F9T Vcc_Ant: Antenna Power Supply

    The VCC_ANT pin is for active antenna powering and typical voltage level should be 5.0 V. The RCB-F9T board is having a current limiting circuitry that limits the current to the RF connector and if too high current consumption is triggered, then over current protection is activated. For this reason, it is important that the connected active antenna does not consume more current than 100 VCC_ANT is used only for active antenna powering.

  • Page 55: Eos/Esd Precautions

    ESD circuit protection 15 kV human body model air discharge Table 23: Antenna specifications for RCB-F9T modules The antenna system should include filtering to ensure adequate protection from nearby transmitters. Take care in the selection of antennas placed close to cellular or Wi-Fi transmitting antennas.

  • Page 56: Esd Protection Measures

    Figure 25: Active antenna EOS protection 4.4.3 Safety precautions The RCB-F9T must be supplied by an external limited power source in compliance with the clause 2.5 of the standard IEC 60950-1. In addition to external limited power source, only Separated or Safety Extra-Low Voltage (SELV) circuits are to be connected to the module including interfaces and antennas.

  • Page 57: Electromagnetic Interference On I/O Lines

    RCB-F9T - Integration manual 4.5 Electromagnetic interference on I/O lines Any I/O signal line with a length greater than approximately 3 mm can act as an antenna and may pick up arbitrary RF signals transferring them as noise into the receiver. This specifically applies to unshielded lines, in which the corresponding GND layer is remote or missing entirely, and lines close to the edges of the printed circuit board.

  • Page 58: In-Band Interference Mitigation

    RCB-F9T - Integration manual 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. 4.5.2 In-band interference mitigation With in-band interference, the signal frequency is very close to the GNSS frequency.

  • Page 59: Product Handling

    RCB-F9T - Integration manual 5 Product handling 5.1 ESD handling precautions RCB-F9T contains highly sensitive electronic circuitry and is an Electrostatic Sensitive Device (ESD). Observe precautions for handling! Failure to observe these precautions can result in severe damage to the GNSS receiver! •...

  • Page 60: Appendix

    10.000000 CFG-TP-DUTY_LOCK_TP1 0x5005002b 20.000000 CFG-TP-TIMEGRID_TP1 0x2005000c 0 - UTC (UTC time reference) Table 24: RCB-F9T-specific UART baud rate, antenna supervisor and time pulse 1 default configurations B Glossary Abbreviation Definition ANSI American National Standards Institute Antenna reference point BeiDou Chinese navigation satellite system...

  • Page 61: C Rcb-F9T Pcb Dimensions

    SBAS Satellite-based Augmentation System Space vehicle, a satellite 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. Figure 26: RCB-F9T PCB dimensions UBX-22004121 - R01...

  • Page 62: Related Documents

    RCB-F9T - Integration manual Related documents RCB-F9T-0 Data sheet, UBX-18053607 RCB-F9T-1 Data sheet, UBX-21004244 TIM 2.20 Interface description, UBX-21048598 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 notifications please register on our homepage https://www.u-blox.com.

  • Page 63: Revision History

    RCB-F9T - Integration manual Revision history Revision Date Name Status / comments 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 Early production information...
  • Page 64 RCB-F9T - Integration manual Contact For complete contact information visit us at www.u-blox.com. u-blox Offices North, Central and South America Headquarters Asia, Australia, Pacific   Europe, Middle East, Africa u-blox America, Inc. u-blox AG u-blox Singapore Pte. Ltd. Phone: +1 703 483 3180...

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