u-blox 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-19003747 - R04

Table of Contents

Summary of Contents for u-blox RCB-F9T

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-19003747 - R04...
Page 2 The information contained herein is provided "as is" and u-blox assumes no liability for the use of the information. No warranty, either express or implied, is given with respect to, including but not limited to, the accuracy, correctness, reliability and ﬁtness...
Page 3: Table Of Contents
RCB-F9T - Integration manual Contents 1 Integration manual structure.................... 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 3.11 Forcing a receiver reset........................42 4 Design............................. 43 4.1 Pin assignment............................43 4.2 Power supply............................43 4.2.1 VCC: Main supply voltage......................43 4.2.2 RCB-F9T VCC_ANT: Antenna power supply................44 4.3 Antenna..............................44 4.4 EOS/ESD precautions.......................... 45 4.4.1 ESD protection measures......................45 4.4.2 EOS precautions...........................46 4.4.3 Safety precautions........................
Page 5: Integration Manual Structure
RCB-F9T - Integration manual 1 Integration manual structure This document provides a wealth of information to enable a successful design with the RCB-F9T timing board. The manual is structured according to system, software and hardware aspects. The ﬁrst section, "System description" outlines the basics of the RCB-F9T timing board.
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 ZED-F9T timing receivers via a communication network.
Page 7: Receiver Functionality
RAM holds the current conﬁguration, which is used by the receiver at run-time. It is constructed on start-up of the receiver from several sources of conﬁguration. The conﬁguration interface and the available keys are described fully in the RCB-F9T Interface description [2].
Page 8: Default Interface Settings
Refer to the u-blox RCB-F9T Interface description [2] for information about further settings. By default the RCB-F9T outputs NMEA 4.10 messages that include satellite data for all GNSS bands being received. This results in a higher-than-before NMEA load output for each navigation period.
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 RCB-F9T - Integration manual In order to use time mode, the receiver's position must be known as exactly as possible. Errors in the ﬁxed position will translate into time errors depending on the satellite constellation. The following procedures can be used to initialize the timing receiver position: •...
Page 11 RCB-F9T - Integration manual 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: Legacy Configuration Interface Compatibility
See Legacy UBX-CFG message ﬁelds reference section in the RCB-F9T Interface description [2]. 3.1.7 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...
Page 13 SV. When a SV is lost after a successful 3D ﬁx (min. four SVs 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 SVs. 3.1.7.3 Navigation output ﬁlters The result of a navigation solution is initially classiﬁed by the ﬁx type (as detailed in the...
Page 14 RCB-F9T - Integration manual 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). 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...
Page 15 RCB-F9T - Integration manual Figure 2: Position publication in static hold mode Figure 3: Flowchart of the static hold mode UBX-19003747 - R04 3 Receiver functionality Page 15 of 54 Early production information...
Page 16: Geofencing
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 RCB-F9T Interface description [2]). Figure 4: Flowchart of the course over ground freezing 3.2 Geofencing...
Page 17: Interface
3.3 Interfaces RCB-F9T provides a UART interface for communication with a host CPU. It is important to isolate interface pins when the RCB-F9T VCC is removed. They can be allowed to ﬂoat or connected to a high impedance. 3.3.1 UART interface RCB-F9T includes one UART port.
Page 18: Predefined Pios
These PIOs are described in this chapter. 3.4.1 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 19: Antenna Short Detection - Ant_Short_N
To recover the antenna status immediately, a power cycle is required or conﬁguring oﬀ and on again the antenna short detection functionality. The antenna voltage control is enabled by default in the RCB-F9T. 3.5.2 Antenna short detection - ANT_SHORT_N...
Page 20: Antenna Short Detection Auto Recovery
$GNTXT,01,01,02,ANTSTATUS=OK*25 MON-RF in u-center: Antenna status = OK. Antenna power status = ON The antenna short detection auto recovery is enabled by default in the RCB-F9T. 3.5.4 Antenna open circuit detection - ANT_DETECT Enable the antenna open circuit detection by setting the conﬁguration item CFG-HW- ANT_CFG_OPENDET to true (1).
Page 21: Multiple Gnss Assistance (Mga)
Obviously the value of this data will diminish as time passes, but in many cases it remains very useful and can signiﬁcantly improve time to ﬁrst ﬁx. There are several ways in which a u-blox receiver can retain useful data while it is powered down, including: •...
Page 22: Assistnow Online
Data supplied by the AssistNow Online Service can be directly uploaded to a u-blox receiver in order to substantially reduce time to ﬁrst ﬁx (TTFF), even under poor signal conditions (typically around 2 seconds; see RCB-F9T Data sheet [1] "Aided start"). The system works by collecting data such as ephemeris and almanac from the satellites through u-blox's "Global...
Page 23 (trying to acquire new signals), it is possible that the internal buﬀers will overﬂow and some messages will be lost. In order to combat this, u-blox receivers support an optional ﬂow control mechanism for assistance.
Page 24 Key name Unit/range Optional Description token String Mandatory The authorization token supplied by u-blox when a client registers to use the service. gnss String Mandatory A comma-separated list of the GNSS for which data should be returned. Valid GNSS are: gps, gal, glo, bds and qzss (case-sensitive).
Page 25: Clocks And Time
For example, if the position is accurate to 100 km or better, the u-blox receiver will choose to go for a more optimistic startup strategy. This will result in quicker startup time. The receiver will decide which strategy to choose, depending on the "pacc"...
Page 26: Navigation Epochs
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). u-blox receivers employ multiple GNSS system times and/or receiver local times (in order to support multiple GNSS systems concurrently), so users should not use UBX messages reporting GNSS system time or receiver local time.
Page 27: Gnss Times
RCB-F9T - Integration manual Consequently, most 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 validity (and...
Page 28: Leap Seconds
23:59:58 will be followed by 00:00:00. u-blox receivers are designed to handle leap seconds in their UTC output and consequently users processing UTC times from either NMEA or UBX messages should be prepared to handle minutes that are either 59 or 61 seconds long.
Page 29: Real Time Clock
Leap second information can be polled from the u-blox receiver with the message UBX-NAV-TIMELS. 3.7.8 Real time clock u-blox receivers contain circuitry to support a real time clock, which (if correctly ﬁtted and powered) keeps time while the receiver is otherwise powered oﬀ. When the receiver powers up, it attempts to use the real time clock to initialize receiver local time and in most cases this leads to appreciably faster ﬁrst ﬁxes.
Page 30: Timing Functionality
RCB-F9T - Integration manual 3.8 Timing functionality The RCB-F9T provides precision time references used by remote or distributed wireless communication, industrial, ﬁnancial, and power distribution equipment. 3.8.1 Time pulse 3.8.1.1 Introduction Figure 8: Time pulse 3.8.1.2 Recommendations • The time pulse can be aligned to a wide variety of GNSS times or to variants of UTC derived...
Page 31 Although u-blox receivers can combine a variety of diﬀerent GNSS times internally, the user must choose a single type of GNSS time and, separately, a single type of UTC for input (on EXTINTs) and output (via the time pulse) and the parameters reported in corresponding messages.
Page 32 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 33: Security
Figure 10: Time pulse signal with the example parameters 3.9 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 threads and report it to the host system.
Page 34: Jamming/Interference Indicator
RCB-F9T - Integration manual algorithms rely on availability of signals from multiple GNSS constellations; the detection does not work in single-GNSS mode. 3.9.2 Jamming/interference indicator The ﬁeld jamInd of the UBX-MON-RF message can be used as an indicator for continuous wave (narrow-band) jammers/interference only. The interpretation of the value depends on the application.
Page 35: U-Blox Protocol Feature Descriptions
RCB-F9T - Integration manual 3.9.3.1 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. 3.9.3.2 Secure ﬁrmware update The ﬁrmware image itself is encrypted and signed by u-blox. The RCB-F9T verify the signature at each start.
Page 36 RCB-F9T - Integration manual 3.10.1.2.1 GPS L1C/A For GPS L1C/A signals, there is a fairly straightforward mapping between the reported subframe and the structure of subframe and words described in the GPS ICD. Each subframe comprises ten data words, which are reported in the same order they are received.
Page 37 RCB-F9T - Integration manual string number and bit 85 is the idle chip, which should always have a value of zero. The meaning of other bits vary with string and frame number. The fourth and ﬁnal 32-bit word in the UBX-RXM-SFRBX message contains frame and superframe numbers (where available).
Page 38 RCB-F9T - Integration manual Note that as the BeiDou 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. 3.10.1.5 Galileo The Galileo E1 C/B and E5 bl/bQ signals both transmit the I/NAV message but in diﬀerent conﬁgurations.
Page 39 RCB-F9T - Integration manual Figure 15: Galileo E1 C/B subframe words 3.10.1.5.2 Galileo E5 bI/bQ For Galileo E5 bI/bQ signals, 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...
Page 40 RCB-F9T - Integration manual Figure 16: Galileo E5 bI/bQ 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 41 RCB-F9T - Integration manual Figure 17: SBAS subframe words 3.10.1.7 QZSS The structure of the data delivered by QZSS L1C/A signals is eﬀectively identical to that for GPS (L1C/A). Similarly the QZSS L2C signal is eﬀectively identical to the GPS (L2C). 3.10.1.8 Summary The following table gives a summary of the diﬀerent data message formats reported by the UBX-...
Page 42: Forcing A Receiver Reset
RCB-F9T - Integration manual 3.11 Forcing a receiver reset Typically, in GNSS receivers, a distinction is made between cold, warm, and hot start, depending on the type of valid information the receiver has at the time of the restart. • Cold start: In cold start mode, the receiver has no information from the last position (e.g.
Page 43: Design
The VCC pin is connected to the main supply voltage. During operation, the current drawn by the module can vary by some orders of magnitude. For this reason, it is important that the supply circuitry be able to support the peak power for a short time (see the RCB-F9T Data sheet [1] for speciﬁcation).
Page 44: 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 45: Eos/Esd Precautions
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 speciﬁed in the u-blox RCB-F9T Data sheet [1]. 4.4.1 ESD protection measures GNSS receivers are sensitive to Electrostatic Discharge (ESD). Special precautions are required when handling.
Page 46: Eos Precautions
Figure 21: 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 47: General Notes On Interference Issues
RCB-F9T - Integration manual emits from unshielded I/O lines. Receiver performance may be degraded when this noise is coupled into 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.
Page 48: Out-Of-Band Interference
RCB-F9T - Integration manual • Maintaining a good grounding concept in the design • Shielding • Layout optimization • Low-pass ﬁltering of noise sources, e.g. digital signal lines • Remote placement of the GNSS antenna, far away from noise sources • Adding an LTE, CDMA, GSM, WCDMA, BT band-pass ﬁlter before antenna 4.5.3 Out-of-band interference...
Page 49: Product Handling
RCB-F9T - Integration manual 5 Product handling 5.1 ESD handling precautions RCB-F9T contain highly sensitive electronic circuitry and are Electrostatic Sensitive Devices (ESD). Observe precautions for handling! Failure to observe these precautions can result in severe damage to the GNSS receiver! •...
Page 50: Appendix
Appendix A RCB-F9T default conﬁgurations The RCB-F9T has diﬀerent default conﬁgurations from the ZED-F9T. Table 16 provides a complete list of the default conﬁguration diﬀerences. See the RCB-F9T Interface description [2] for additional information. Conﬁguration item Key ID Type Scale...
Page 51 RCB-F9T - Integration manual Abbreviation Deﬁnition SBAS Satellite-based Augmentation System Space Vehicle, a satellite u-blox QZSS Quasi-Zenith Satellite System UBX-19003747 - R04 Appendix Page 51 of 54 Early production information...
Page 52: Related Documents
RCB-F9T Data sheet, doc. no. UBX-18053607 RCB-F9T Interface description, doc. no. UBX-19003606 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 (http://www.u-blox.com). UBX-19003747 - R04...
Page 53: Revision History
RCB-F9T - Integration manual Revision history Revision Date Name Status / comments 19-Mar-2019 tkoi Advance information 18-Jun-2019 tkoi Early production information 16-Jan-2020 tkoi Early production information Updated type number 25-Feb-2020 jhak Updated minimum and maximum gains in Antenna speciﬁcations table. UBX-19003747 - R04...
Page 54 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...