ZED-F9T u-blox F9 high accuracy timing module Integration manual Abstract This document describes the features and application of ZED-F9T, a multiband GNSS module offering nanosecond level timing accuracy. www.u-blox.
ZED-F9T - Integration manual Document information Title ZED-F9T Subtitle u-blox F9 high accuracy timing module Document type Integration manual Document number UBX-19005590 Revision and date R05 Document status Early production information Disclosure restriction C1-Public 18-Nov-2020 This document applies to the following products: Product name Type number Firmware version ZED-F9T ZED-F9T-00B-01 TIM 2.
ZED-F9T - Integration manual Contents 1 Integration manual structure............................................................................................ 6 2 System description...............................................................................................................7 2.1 Overview.................................................................................................................................................... 7 2.1.1 Differential timing............................
ZED-F9T - Integration manual 3.7.1 Authorization................................................................................................................................ 37 3.7.2 Multiple servers............................................................................................................................ 37 3.7.3 Preserving information during power-off................................................................................37 3.7.4 AssistNow Online................................
ZED-F9T - Integration manual 4.8.3 4.8.4 4.8.5 4.8.6 4.8.7 RF front-end circuit options...................................................................................................... 76 Antenna/RF input........................................................................................................................ 77 Ground pads.................................................................................................................................. 78 Schematic design................
ZED-F9T - Integration manual 1 Integration manual structure This document provides a wealth of information to enable a successful design with the ZED-F9T module. The manual is structured according to system, software and hardware aspects. The first section, "System description" outlines the basics of the ZED-F9T. The following section "Receiver functionality" provides an exhaustive description of the receiver's functionality.
ZED-F9T - Integration manual 2 System description 2.1 Overview The ZED-F9T is a multi-band GNSS module offering 5 ns (1-sigma) timing accuracy with unparalleled low power consumption. The ZED-F9T incorporates the u-blox F9 multi-band platform in a small surface-mount device with a form factor of 22 x 17 mm. 2.1.1 Differential timing The u-blox ZED-F9T high accuracy timing receiver takes local timing accuracy to the next level with its differential timing mode.
ZED-F9T - Integration manual 2.2 Architecture The ZED-F9T receiver provides all the necessary RF and baseband processing to enable multi-band, multi-constellation operation. The block diagram below shows the key functionality. 2.2.1 Block diagram Figure 1: ZED-F9T block diagram An active antenna is mandatory with the ZED-F9T.
ZED-F9T - Integration manual 3 Receiver functionality This section describes the ZED-F9T operational features and their configuration. 3.1 Receiver configuration The ZED-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. It is constructed on start-up of the receiver from several sources of configuration.
ZED-F9T - Integration manual For more information about the default configuration, see the ZED-F9T Interface description [2]. 3.1.3 Default interface settings Interface Settings UART1 output 38400 baud, 8 bits, no parity bit, 1 stop bit. NMEA protocol is enabled by default and GGA, GLL, GSA, GSV, RMC, VTG, TXT messages are output by default. UBX and RTCM 3.3 protocols are enabled by default but no output messages are enabled by default. UART1 input 38400 baud, 8 bits, no parity bit, 1 stop bit.
ZED-F9T - Integration manual Interface Configuration groups I2C CFG-I2C-*, CFG-I2CINPROT-*, CFG-I2COUTPROT-* SPI CFG-SPI-*, CFG-SPIINPROT-*, CFG-SPIOUTPROT-* Table 2: Interface configurations 3.1.4.2 Message output configuration The rate of the supported output messages is configurable. If the rate configuration value is zero, then the corresponding message will not be output. Values greater than zero indicate how often the message is output.
ZED-F9T - Integration manual Configuration item Description Comments CFG-HW-ANT_CFG_OPENDET_POL Open antenna detection polarity Set to 1 if the required logic polarity is active-low (default) CFG-HW-ANT_CFG_PWRDOWN Power down antenna supply if short circuit is detected CFG-HW-ANT_CFG_PWRDOWN_POL Power down antenna logic polarity Set to 1 if the required logic polarity is active-high (default) CFG-HW-ANT_CFG_RECOVER Enable auto recovery in the event of a short circuit To use this feature, short c
ZED-F9T - Integration manual 3.1.5.1 RTCM corrections RTCM is a binary data protocol for communication of GNSS correction information. The ZED-F9T high accuracy timing receiver supports RTCM as specified by RTCM 10403.3, Differential GNSS (Global Navigation Satellite Systems) Services – 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.
ZED-F9T - Integration manual • A minimum observation time defines the minimum observation time independent of the actual number of fixes used for the position estimate. Values can range from one day for high accuracy requirements to a few minutes for coarse position determination. • A 3D position standard deviation defines a limit on the spread of positions that contribute to the calculated mean. Survey-in ends when both requirements are successfully met.
ZED-F9T - Integration manual For high precision (mm) coordinates use CFG-TMODEECEF_X_HP, CFG-TMODE-ECEF_Y_HP, CFGTMODE-ECEF_Z_HP. The same applies with corresponding coordinates used with CFG-TMODEPOS_TYPE=LLH. If the timing receiver is moved during operation then new position coordinates must be configured. 3.1.5.5 Master reference station When the ZED-F9T high accuracy timing receiver acts as a master timing station, it sends RTCM 3.3 differential corrections to slave receivers.
ZED-F9T - Integration manual Connect the slave receiver to the reference server or to the NTRIP server. When the slave receives the configured RTCM correction stream, it will automatically start using the corrections. Reception of RTCM 4072.1 is required to start using differential correction data. 3.1.
ZED-F9T - Integration manual Platform Max altitude [m] Max horizontal velocity [m/s] Max vertical velocity [m/s] Sanity check type Max position deviation At sea 500 25 5 Altitude and velocity Medium Airborne <1g 80000 100 6400 Altitude Large Airborne <2g 80000 250 10000 Altitude Large Airborne <4g 80000 500 20000 Altitude Large Wrist 9000 30 20 Altitude and velocity Medium Table 11: Dynamic platform model details Applying dynamic platform models designed for high accele
ZED-F9T - Integration manual UBX-NAV-STATUS message also reports whether a fix is valid in the gpsFixOK flag. These messages have only been retained for backwards compatibility and users are recommended to use the UBX-NAV-PVT message. 3.1.7.3.1 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).
ZED-F9T - Integration manual Figure 2: Position publication in static hold mode Figure 3: Flowchart of the static hold mode UBX-19005590 - R05 C1-Public 3 Receiver functionality Early production information Page 19 of 87
ZED-F9T - 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.
ZED-F9T - Integration manual The geofencing feature allows for the configuration of up to four circular areas (geofences) on the Earth'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. 3.2.2 Interface Geofencing can be configured using the CFG-GEOFENCE-* configuration group. The geofence evaluation is active whenever there is at least one geofence configured.
ZED-F9T - Integration manual The following table lists all the logging-related messages: Message Description UBX-LOG-CREATE Creates a log file and activates the logging system UBX-LOG-ERASE Erases a log file and deactivates the logging subsystem UBX-LOG-INFO Provides information about the logging system UBX-LOG-STRING Enables a host process to write a string of bytes to the log file Table 13: Logging control and configuration messages Message Description UBX-LOG-RETRIEVE Starts the log retrieval p
ZED-F9T - Integration manual also report the number of entries currently in the log together with the time and date of the newest and oldest messages which have a valid time stamp. Log entries are compressed and have housekeeping information associated with them, so the actual space occupied by log messages may be difficult to predict. The minimum size for a position fix entry is 9 bytes and the maximum 24 bytes, the typical size is 10 or 11 bytes.
ZED-F9T - Integration manual recorded. If a log entry is retrieved with a satellite count equal to the maximum this means that value or more. The maximum count is 51. • A horizontal accuracy estimate is recorded to give an indication of fix quality. This is an approximate compressed representation of the accuracy as determined by the fix process. Any accuracy less than 0.7 m will be recorded as 0.7 m and any value above 1 km will be recorded as 1 km.
ZED-F9T - Integration manual The UBX-LOG-FINDTIME message can be used to search a log for the index of the first entry less than or equal to the given time. This index can then be used with the UBX-LOG-RETRIEVE message to provide timebased retrieval of log entries. 3.3.6 Command message acknowledgment Some log operations may take a long time to execute because of the time taken to write to flash memory.
ZED-F9T - Integration manual Figure 9: ZED-F9T output isolation Figure 10: ZED-F9T input isolation 3.4.1 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 no support for setting different baud rates for reception and transmission. The ZED-F9T includes two UART serial ports.
ZED-F9T - Integration manual Baud rate Data bits Parity Stop bits 230400 8 none 1 460800 8 none 1 921600 8 none 1 Table 17: Possible UART interface configurations The default baud rate is 38400 baud. To prevent buffering problems it is recommended not to run at a lower baud rate than the default.
ZED-F9T - Integration manual Figure 11: I2C register layout 3.4.2.2 Read access types There are two I2C read transfer forms: • The "random access" form: includes a slave register address and allows any register to be read. • The "current address" form: omits the register address. Figure 12 shows the format of the first one, the "random access" form of the request.
ZED-F9T - Integration manual Figure 12: I2C random read access If the second form, "current address" is used, an address pointer in the receiver is used to determine which register to read. This address pointer will increment after each read unless it is already pointing at register 0xFF, the highest addressable register, in which case it remains unaltered.
ZED-F9T - Integration manual Figure 14: I2C write access 3.4.3 SPI interface The ZED-F9T high accuracy timing receiver has an SPI slave interface that can be selected by setting D_SEL = 0. The SPI slave interface is shared with UART1 and I2C port, the physical pins are same. The SPI pins available are: • SPI_MISO (TXD) • SPI_MOSI (RXD) • SPI_CS_N • SPI_CLK See more information about communication interface selection from D_SEL section. The SPI interface is designed to allow communication to a host CPU.
ZED-F9T - Integration manual Figure 15: SPI back-to-back read/write access 3.4.4 USB interface A single USB port is provided for host communication purposes. The USB 2.0 FS (Full speed, 12 Mbit/s) interface can be used for host communication. Due to the hardware implementation, it may not be possible to certify the USB interface. If the receiver executes code from internal ROM (i.e.
ZED-F9T - Integration manual Figure 16: ZED-F9T example circuit for USB interface R11 = 100 k Ω is recommended R4, R5 = 27 Ω is recommended 3.5 Predefined PIOs In addition to the communication ports, there are some predefined PIOs provided by ZED-F9T to interact with the receiver. These PIOs are described in this chapter. If hardware backup mode is used a proper isolation of the interfaces is needed. 3.5.
ZED-F9T - Integration manual It is recommended to have the possibility to pull the SAFEBOOT_N pin low in the application. This can be provided using an externally connected test point or a host I/O port. 3.5.4 TIMEPULSE The ZED-F9T provides time pulse signals on the TIMEPULSE and TIMEPULSE2 pins. More information about the time pulse feature and its configuration can be found in the Time pulse section. 3.5.
ZED-F9T - Integration manual Figure 17: ZED-F9T antenna supervisor The bias-t inductor must be chosen for multi-band operation; a value of 47 nH ±5% is required for our recommended Murata part, with the current limited below its 300 mA rating. See Antenna bias section for additional information. Circuit shows buffer [U4]. Buffer is not strictly necessary when supplied from VCC. It is only required when supplying antenna voltage that is not obtained from or controlled by module VCC or VCC_RF .
ZED-F9T - Integration manual $GNTXT,01,01,02,ANTSTATUS=OK*25 ANTSUPERV=AC indicates antenna control is activated 3.6.2 Antenna short detection - ANT_SHORT_N Enable the antenna short detection ANT_CFG_SHORTDET to true (1). by setting the configuration item CFG-HW- Result: • UBX-MON-RF in u-center "Message View": Antenna status = OK. Antenna power status = ON • ANT_OFF = active high to disable an external antenna therefore the pin is low to enable an external antenna.
ZED-F9T - Integration manual Then if antenna is shorted (ANT_SHORT_N pulled low): • $GNTXT,01,01,02,ANTSTATUS=SHORT*73 • UBX-MON-RF in u-center "Message View": Antenna status = SHORT. Antenna power status = OFF • ANT_OFF = high (to disable - active high) After a time out period receiver will re-test the short condition by enabling ANT_OFF = LOW If a short is not present it will report antenna condition is OK: $GNTXT,01,01,02,ANTSTATUS=OK*25 UBX-MON-RF in u-center "Message View": Antenna status = OK.
ZED-F9T - Integration manual AssistNow Online optionally provides satellite ephemerides, health information and time aiding data suitable for GNSS receiver systems with direct internet access. 3.7.1 Authorization The AssistNow Online Service is only available to u-blox customers. To use the services, customers will need to obtain an authorization token from u-blox. This token must be supplied as a parameter whenever a request is made to either service.
ZED-F9T - Integration manual Figure 18: MGA architecture The data returned by the AssistNow Online Service is a sequence of UBX-MGA messages, starting with an estimate of the current time in the form of a UBX-MGA-INI-TIME_UTC message. AssistNow Online supports GPS, GLONASS, BeiDou, Galileo, and QZSS. Customers may choose to use third party sources of assistance data instead of using the AssistNow Online Service.
ZED-F9T - Integration manual • Optionally send UBX-MGA-INI-TIME_UTC followed by hardware time synchronization pulse. • Send the UBX messages obtained from the AssistNow Online Service to the receiver. 3.7.4.3 Flow control u-blox receivers aim to process incoming messages as quickly as possible, but there will always be a small delay in processing each message. Uploading assistance data to the receiver can involve sending as many as one hundred individual messages to the receiver, one after the other.
ZED-F9T - Integration manual Key name Unit/range Optional datatype String Mandatory A comma-separated list of the data types required by the client. Valid data types are: eph, alm, aux and pos. Time data is always returned for each request. If the value of this parameter is an empty string, only time data will be returned. lat Numeric [degrees] Optional Approximate user latitude in WGS 84 expressed in degrees and fractional degrees. Must be in range -90 to 90. Example: lat=47.2.
ZED-F9T - Integration manual If both the network latency and the client latency can safely be assumed to be very low (or are known), the client can choose to set the accuracy of the time message (tacc) to a much smaller value (e.g. 0.5 s). This will result in a faster TTFF. The latency can also be adjusted as needed. However, these fields should be used with caution: if the time accuracy is not correct when the time data reaches the receiver, the receiver may experience prolonged or even failed startups.
ZED-F9T - Integration manual Clearly when the receiver has chosen to use the GPS time-base for its GNSS system time, conversion to GPS time requires no work at all, but conversion to UTC requires knowledge of the number of leap seconds since GPS time started (and other minor correction terms). The relevant GPS-to-UTC conversion parameters are transmitted periodically (every 12.5 minutes) by GPS satellites, but can also be supplied to the receiver via the UBX-MGA-GPS-UTC aiding message.
ZED-F9T - Integration manual Time reference Message UTC time UBX-NAV-TIMEUTC Table 21: GNSS times 3.8.5 Time validity Information about the validity of the time solution is given in the following form: • Time validity: Information about time validity is provided in the valid flags (e.g. validDate and validTime flags in the UBX-NAV-PVT message). If these flags are set, the time is known and considered valid for use.
ZED-F9T - Integration manual When the nano field is negative, the number of seconds (and maybe minutes, hours, days, months or even years) will have been rounded up. Therefore, some or all of them must be adjusted in order to get the correct time and date. Thus in an extreme example, the UTC time 23:59:59.9993 on 31st December 2011 would be reported as: year: 2012, month: 1, day: 1, hour: 0, min: 0, sec: 0, nano: -700000.
ZED-F9T - Integration manual Fortunately, although BeiDou and Galileo have similar representations of time, they transmit sufficient bits for the week number to be unambiguous for the foreseeable future (the first ambiguity will be in 2078 for Galileo and not until 2163 for BeiDou). GLONASS has a different structure, based on a time of day, but again transmits sufficient information to avoid any ambiguity during the expected lifetime of the system (the first ambiguous date will be in 2124).
ZED-F9T - Integration manual Figure 19: Time pulse 3.9.1.2 Recommendations • The time pulse can be aligned to a wide variety of GNSS times or to variants of UTC derived from them (see the chapter on time bases). However, it is strongly recommended that the choice of time base is aligned with the available GNSS signals (so to produce GPS time or UTC(USNO), ensure GPS signals are available, and for GLONASS time or UTC(SU) ensure the presence GLONASS signals).
ZED-F9T - Integration manual Figure 20: Time pulse and TIM-TP 3.9.1.3 GNSS time bases GNSS receivers must handle a variety of different time bases as each GNSS has its own reference system time. What is more, although each GNSS provides a model for converting their system time into UTC, they all support a slightly different variant of UTC. So, for example, GPS supports a variant of UTC as defined by the US National Observatory, while BeiDou uses UTC from the National Time Service Center, China (NTSC).
ZED-F9T - Integration manual 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. Time pulse signal can be configured using the configuration group CFG-TP-*. 3.9.1.
ZED-F9T - Integration manual • CFG-TP-POL_TP1 = 1 • CFG-TP-PERIOD_LOCK_TP1 = 100 000 µs • CFG-TP-LEN_LOCK_TP1 = 100 000 µs The 1 Hz output is maintained whether or not the receiver is locked to GPS time. The alignment to TOW can only be maintained when GPS time is locked. Figure 21: Time pulse signal with the example parameters 3.9.2 Timemark The receiver can be used to provide an accurate measurement of the time at which a pulse was detected on the external interrupt pin.
ZED-F9T - Integration manual Figure 22: Timemark 3.10 Security The security concept of ZED-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. Other functions try to mitigate the thread and allow the receiver to operate normally.
ZED-F9T - Integration manual The spoofing detection feature monitors the GNSS signals for suspicious patterns indicating that the receiver is being spoofed. A flag in UBX-NAV-STATUS message (flags2 - spoofDetState) alerts the user to potential spoofing. The spoofing detection feature monitors suspicious changes in the GNSS signal indicating external manipulation. Therefore the detection is only successful when the signal is genuine first and when the transition to the spoofed signal is being observed directly.
ZED-F9T - Integration manual The monitoring algorithm relies on comparing the currently measured spectrum with a reference from when a good fix was obtained. Thus the monitor will only function when the receiver has had at least one (good) first fix, and will report "Unknown" before this time. The monitor is reporting any currently detected interference over all currently configured signal bands. 3.10.3 GNSS receiver integrity 3.10.3.
ZED-F9T - Integration manual The meaning of the content of each subframe depends on the sending GNSS and is described in the relevant interface control documents (ICD). 3.11.1.2 GPS The data message structure in the GPS L1C/A (LNAV) and L2C/L5 (CNAV) signals is different and thus the UBX-RXM-SFRBX message structure differs as well. For the GPS L1C/A and L2C/L5 signals it is as follows: 3.11.1.2.
ZED-F9T - Integration manual Figure 24: GPS L2C subframe words 3.11.1.3 GLONASS For GLONASS L1OF and L2OF signals, 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, whilst bits 81 to 84 are a string number and bit 85 is the idle chip, which should always have a value of zero.
ZED-F9T - Integration manual Figure 25: 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". 3.11.1.4 BeiDou For BeiDou signals there is a fairly straightforward mapping between the reported subframe and the structure of subframe and words described in the BeiDou ICD.
ZED-F9T - Integration manual 3.11.1.5.1 Galileo E1-B For the Galileo E1-B signal, 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.
ZED-F9T - Integration manual 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). 3.11.1.5.2 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.
ZED-F9T - Integration manual Figure 28: Galileo E5b subframe words 3.11.1.6 SBAS For SBAS (L1C/A) signals each reported subframe contains eight 32-bit data words to deliver the 250 bits transmitted in each SBAS data block.
ZED-F9T - Integration manual Figure 29: SBAS subframe words 3.11.1.7 QZSS The structure of the data delivered by QZSS L1C/A signals is effectively identical to that for GPS (L1C/A). Similarly the structure of the data delivered by the QZSS L2C signal is effectively identical to GPS (L2C). 3.11.1.
ZED-F9T - Integration manual 3.12 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. time, velocity, frequency etc.) at startup. Therefore, the receiver must search the full time and frequency space, and all possible satellite numbers.
ZED-F9T - Integration manual 4 Design This section provides information to help carry out a successful schematic and PCB design integrating the ZED-F9T. Do not load Pin 4 (ANT_DETECT) with a capacitance more than 1 nF. 4.1 Pin assignment The pin assignment of the ZED-F9T module is shown in Figure 30. The defined configuration of the PIOs is listed in Table 25. The ZED-F9T is an LGA package with the I/O on the outside edge and central ground pads. Figure 30: ZED-F9T pin assignment Pin no.
ZED-F9T - Integration manual Pin no.
ZED-F9T - Integration manual Pin no. Name I/O Description 51 EXTINT I External Interrupt Pin 52 EXTINT2 I External Interrupt Pin 2 53 TIMEPULSE O Time pulse 54 TIMEPULSE2 O Time pulse 2 Table 25: ZED-F9T pin assignment 4.2 Power supply The u-blox ZED-F9T module has three power supply pins: VCC, V_BCKP and V_USB. 4.2.1 VCC: Main supply voltage 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.
ZED-F9T - Integration manual Allow all I/O including UART and other interfaces to float or connect to a high impedance in HW backup mode (V_BCKP supplied when VCC is removed). See the Interfaces section. Real-time clock (RTC) The real-time clock (RTC) is driven by a 32-kHz oscillator using an RTC crystal. If VCC is removed whilst a battery is connected to V_BCKP, most of the receiver is switched off leaving the RTC and BBR powered.
ZED-F9T - Integration manual Figure 32: Minimal ZED-F9T design For a minimal design with the ZED-F9T GNSS modules, the following functions and pins should be considered: • • • • • Connect the power supply to VCC and V_BCKP. If hot or warm start operations are needed, connect a backup battery to V_BCKP. If USB is not used connect V_USB to ground. Ensure an optimal ground connection to all ground pins of the ZED-F9T GNSS module. If antenna bias is required, see ZED-F9T antenna bias section. 4.
ZED-F9T - Integration manual Figure 33: u-blox low cost dual-band antenna internal structure A suitable ground plane is required for the antenna to achieve good performance. Location of the antenna is critical to reach the stated performance. Unsuitable locations could include, under vehicle dash, rear-view mirror location, etc.
ZED-F9T - Integration manual If customers do not want to make use of the antenna supervisor function the filtered VCC_RF supply voltage output can supply the antenna if the supply voltage of the ZED-F9T module matches the antenna working voltage (e.g. 3.0 V). A series current limiting resistor is required to prevent short circuits destroying the bias-t inductor. The bias-t inductor must be chosen for multi-band operation, a value of 47 nH ±5% is recommended for the recommended Murata L part.
ZED-F9T - Integration manual Figure 35: ZED-F9T reference design for antenna bias L1: Murata LQG15HS47NJ02 0402 47 N 5% 0.30 A -55/+125 C D1: TYCO, 0.25PF, PESD0402-140 -55/+125C C3: MURATA GRM033R61E104KE14 CER X5R 0201 100N 10% 25V R2: RES THICK FILM CHIP 1206 10R 5% 0.25W It is recommended to use active current limiting.
ZED-F9T - Integration manual bias supply due to power dissipation. Take the current limit capability of the antenna bias supply into consideration. In the case where the module supplies the voltage via VCC_RF, a higher value resistor will be needed to ensure the module supply inductor is protected. The current should be limited to below 150 mA at the module supply voltage under short-circuit conditions.
ZED-F9T - Integration manual Figure 38: RF ESD precautions 4.5.2 EOS precautions Electrical overstress (EOS) usually describes situations when the maximum input power exceeds the maximum specified 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 whether the chip structures have been damaged by ESD or EOS.
ZED-F9T - Integration manual permanently. Another type of interference can be caused by noise generated at the PIO pins that 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.
ZED-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 4.6.3 Out-of-band interference Out-of-band interference is caused by signal frequencies that are different from the GNSS carrier frequency.
ZED-F9T - Integration manual High temperature drift and air vents can affect the GNSS performance. For best performance, avoid high temperature drift and air vents near the receiver. 4.7.3 Package footprint, copper and paste mask Copper and solder mask dimensioning recommendations for the ZED-F9T module packages are provided in this section. These are recommendations only and not specifications.
ZED-F9T - Integration manual 4.7.3.2 Paste mask Figure 41: ZED-F9T suggested paste mask 4.7.4 Layout guidance The presented layout guidance reduces the risk of performance issues at design level. 4.7.4.1 RF In trace The RF in trace has to work in the combined GNSS signal bands. For FR-4 PCB material with a dielectric permittivity of for example 4.7, the trace width for the 50 Ω line impedance can be calculated.
ZED-F9T - Integration manual Figure 42: RF input trace The RF_IN trace on the top layer should be referenced to a suitable ground layer. 4.7.4.2 Vias for the ground pads The ground pads under the ZED-F9T high accuracy timing receiver need to be grounded with vias to the lower ground layer of the PCB. A solid ground layer fill on the top layer of the PCB is recommended. This is shown in the figure below. Figure 43: Top layer fill and vias 4.7.4.
ZED-F9T - Integration manual Figure 44: VCC pads 4.8 Design guidance 4.8.1 General considerations Do not load Pin 4 (ANT_DETECT) with a capacitance more than 1 nF. Check power supply requirements and schematic: • Is the power supply voltage within the specified range and noise-free? • If USB is not used, connect the V_USB pin to ground. • It is recommended to have a separate LDO for V_USB that is enabled by the module VCC. This is to comply with the USB self-powered specification.
ZED-F9T - Integration manual 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.
ZED-F9T - Integration manual • Bias-t inductor must be L1 and L2 band frequency selected with high impedance in the GNSS band. • Ensure RF trace is tuned for 50 Ω to ensure L1 and L2 bandwidth. 4.8.5 Ground pads Ensure the ground pads of the module are connected to ground. 4.8.6 Schematic design For a minimal design with the ZED-F9T GNSS modules, consider the following functions and pins: • Connect the power supply to VCC and V_BCKP.
ZED-F9T - Integration manual 5 Product handling 5.1 ESD handling precautions ZED-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! • • Unless there is a galvanic coupling between the local GND (i.e. the work table) and the PCB GND, then the first point of contact when handling the PCB must always be between the local GND and PCB GND.
ZED-F9T - Integration manual As a reference, see “IPC-7530 Guidelines for temperature profiling for mass soldering (reflow and wave) processes”, published in 2001. Preheat phase During the initial heating of component leads and balls, residual humidity will be dried out. Note that the preheat phase does not replace prior baking procedures. • Temperature rise rate: max 3 °C/s. If the temperature rise is too rapid in the preheat phase, excessive slumping may be caused • Time: 60 – 120 s.
ZED-F9T - Integration manual Modules must not be soldered with a damp heat process. Optical inspection After soldering the module, consider optical inspection. Cleaning Do not clean with water, solvent, or ultrasonic cleaner: • Cleaning with water will lead to capillary effects where water is absorbed into the gap between the baseboard and the module. The combination of residues of soldering flux and encapsulated water leads to short circuits or resistor-like interconnections between neighboring pads.
ZED-F9T - Integration manual Casting If casting is required, use viscose or another type of silicon pottant. The OEM is strongly advised to qualify such processes in combination with the module before implementing this in the production. Casting will void the warranty. Grounding metal covers Attempts to improve grounding by soldering ground cables, wick or other forms of metal strips directly onto the EMI covers is done at the customer’s own risk.
ZED-F9T - Integration manual Figure 47: ZED-F9T tape dimensions (mm) 5.4 Reels The ZED-F9T receivers are deliverable in quantities of 250 pieces on a reel. The receivers are shipped on reel type B, as specified in the u-blox Package Information Guide [3]. 5.5 Moisture sensitivity levels The moisture sensitivity level (MSL) for ZED-F9T is specified in the table below. Package MSL level LGA 4 Table 27: MSL level For MSL standard see IPC/JEDEC J-STD-020, which can be downloaded from www.jedec.org.
ZED-F9T - Integration manual Appendix A Glossary Abbreviation Definition ANSI American National Standards Institute ARP Antenna reference point BeiDou Chinese navigation satellite system BBR Battery-backed RAM CDMA Code-division multiple access EMC Electromagnetic compatibility EMI Electromagnetic interference EOS Electrical overstress EPA Electrostatic protective area ESD Electrostatic discharge Galileo European navigation satellite system GLONASS Russian navigation satellite syste
ZED-F9T - Integration manual Related documents [1] [2] [3] ZED-F9T Data sheet, UBX-18053713 ZED-F9T Interface description, UBX-18053584 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.
ZED-F9T - Integration manual Revision history Revision Date Name Status / comments R01 15-Mar-2019 tkoi Advance information Added a design-in restriction for ANT_DETECT pin in section Design. Mechanical specification figure updated in section Layout.
ZED-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. Phone: +1 703 483 3180 E-mail: info_us@u-blox.com u-blox AG Phone: +41 44 722 74 44 E-mail: info@u-blox.com Support: support@u-blox.com u-blox Singapore Pte. Ltd. Phone: +65 6734 3811 E-mail: info_ap@u-blox.com Support: support_ap@u-blox.
