Ublox EVK-F9T User manual

UBX-21040453 - R01
C1- Public www.u-blox.com
EVK-F9T
Evaluation kit
User guide
Abstract
This document describes the structure and use of the EVK-F9T evaluation kit and provides
information for evaluating and testing u-blox F9 positioning technology for timing and raw data
applications.

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Document information
Title
EVK-F9T
Subtitle
Evaluation kit
Document type
User guide
Document number
UBX-21040453
Revision and date
R01
6-Jun-2022
Disclosure restriction
C1- Public
Product status
Corresponding content status
In development /
Prototype
Objective specification
Target values. Revised and supplementary data will be published later.
Engineering sample
Advance information
Data based on early testing. Revised and supplementary data will be published later.
Initial production
Early production information
Data from product verification. Revised and supplementary data may be published later.
Mass production /
End of life
Production information
Document contains the final product specification.
This document applies to the following products:
Product name
Ordering code
Firmware version
Application version
PCN reference
Product status
EVK-F9T
EVK-F9T-10
TIM 2.20
N/A
Initial production
u-blox or third parties may hold intellectual property rights in the products, names, logos and designs included in this
document. Copying, reproduction, modification or disclosure to third parties of this document or any part thereof is only
permitted with the express written permission of u-blox.
The information contained herein is provided “as is” and u-blox assumes no liability for its use. No warranty, either express or
implied, is given, including but not limited to, with respect to the accuracy, correctness, reliability and fitness for a particular
purpose of the information. This document may be revised by u-blox at any time without notice. For the most recent
documents, visit www.u-blox.com.
Copyright © u-blox AG.

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Contents
Contents ..........................................................................................................................................................3
1Product description ..............................................................................................................................4
1.1 Overview........................................................................................................................................................4
1.2 Kit includes ...................................................................................................................................................4
1.3 Software and documentation...................................................................................................................4
1.3.1 u-center GNSS evaluation software ...............................................................................................4
1.4 System requirements ................................................................................................................................ 4
2Specifications .........................................................................................................................................5
2.1 Safety precautions ..................................................................................................................................... 5
2.1.1 Certifications ....................................................................................................................................... 5
3Setting up.................................................................................................................................................6
3.1 u-center installation ...................................................................................................................................6
3.2 Hardware installation................................................................................................................................. 6
3.3 Default interface settings.........................................................................................................................6
4Device description.................................................................................................................................8
4.1 Interface connection and measurement................................................................................................8
4.2 Active antenna.............................................................................................................................................8
4.3 Evaluation unit.............................................................................................................................................8
4.3.1 Antenna connector (RF IN) ............................................................................................................... 8
4.3.2 Timepulse connector (TP1) ..............................................................................................................8
4.3.3 USB connector.....................................................................................................................................9
4.3.4 D9 connector (RS232) ....................................................................................................................... 9
4.3.5 RST button........................................................................................................................................... 9
4.3.6 Safe boot button...............................................................................................................................10
4.3.7 Slide switch ........................................................................................................................................10
4.3.8 Pin header...........................................................................................................................................10
4.3.9 LED.......................................................................................................................................................11
4.3.10 EXT connector ...................................................................................................................................11
5GNSS current measurement........................................................................................................... 12
6Block diagram ...................................................................................................................................... 13
7Board layout.......................................................................................................................................... 14
8Schematic ............................................................................................................................................. 16
9Troubleshooting.................................................................................................................................. 18
10 Common evaluation pitfalls ............................................................................................................ 20
Related documentation ........................................................................................................................... 21
Revision history.......................................................................................................................................... 21
Appendix ....................................................................................................................................................... 22
Contact.......................................................................................................................................................... 23

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1Product description
1.1 Overview
The EVK-F9T evaluation kit simplifies the evaluation of the high-performance u-blox F9 Timing
products. The built-in USB interface provides both power supply and high-speed data transfer and
eliminates the need for an external power supply. The u-blox evaluation kits are compact, and their
user-friendly interface and power supply make them ideally suited for use in laboratories, vehicles,
and outdoor locations. Furthermore, they can be used with a notebook PC, making them the perfect
companion through all stages of design-in projects.
Evaluation Kit
Description
Suitable for
EVK-F9T
u-blox F9 high accuracy timing module with
L1/L5/E5a bands
ZED-F9T-10B, RCB-F9T-1 and LEA-F9T-10B
Table 1: List of products supported by EVK-F9T evaluation kit
1.2 Kit includes
The delivered package contains:
•Compact 105 x 64 x 26 mm EVK-F9T evaluation unit
•Micro USB cable
•ANN-MB1 multi-band (L1/L5) active GNSS antenna with 3 m cable
•EVK Welcome card
☞For EVK-F9T Product summary, see start.u-blox.com.
1.3 Software and documentation
The EVK installation software (and documentation) package can be downloaded from the web; see
the Quick Start card for the URL.
1.3.1 u-center GNSS evaluation software
The installation software includes u-center, an interactive tool for configuration, testing,
visualization, and data analysis of GNSS receivers. It provides useful assistance during all phases of a
system integration project. The latest version of u-center should be used.
1.4 System requirements
•PC with USB interface (compatible with USB 2.0)
•Operating system: Microsoft Windows 7 onwards (x86 and x64 versions)
•Internet connection for the first time use

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2Specifications
Parameter
Specification
Serial interfaces
1 micro–USB V2.0
1 RS232, max baud rate 921,6 kBd
DB9 +/- 12 V level
14 pin –3.3 V logic
1 DDC (I2C compatible) max 400 kHz
1 SPI –clock signal max 5,5 MHz –SPI DATA max 1 Mbit/s
Timing interfaces
2 timepulse outputs through main connector PINs
1 timepulse output through SMA
1 timepulse output through RS232
2 external interrupt inputs
Dimensions
105 x 64 x 26 mm
Power supply
5 V via USB or powered via external power supply pin 14
(V5_IN) and pin 13 (GND)
Normal operating temperature
-40 °C to +65 °C
Table 2: EVK-F9T specifications
2.1 Safety precautions
EVK-F9T must be supplied by a PS1 class limited power source. See section 6.2.2.4 of IEC 62368-
1:2018 [5] for more information on the PS1 class.
In addition to a limited power source, only ES1 class circuits are to be connected to the EVK-F9T,
including interfaces and antennas. See section 5.2.1.1 of IEC 62368-1:2018 [5] for more information
on the ES1 class.
2.1.1 Certifications
The EVK-F9T is designed to in compliance with the essential requirements and
other relevant provisions of Radio Equipment Directive (RED) 2014/53/EU.
The EVK-F9T complies with the Directive 2011/65/EU (EU RoHS 2) and its
amendment Directive (EU) 2015/863 (EU RoHS 3).
Declaration of Conformity (DoC) is available on the u-blox website.

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3Setting up
3.1 u-center installation
u-center, the u-blox interactive evaluation software tool is required for configuration, testing,
visualization and data analysis of u-blox GNSS receivers as well as EVKs. The provided user guide
together with the evaluation tool provide useful assistance during all phases of a system integration
project.
u-center can be downloaded from www.u-blox.com/product/u-center. Once the zipped installer file
is downloaded, unzip it and double-click the exe file. The u-center software will be installed on your
system and placed under the “u-blox” folder in the “Start > Programs” menu, you can also choose
the destination folder for the program installation. After a successful installation, u-center can be
started from the Start menu (All Programs > u-blox > u-center > u-center). For more information on
how to evaluate using u-center, refer to the u-center User guide [4].
The required Microsoft CDC-ACM driver for Windows 10 USB interface is available from the
Microsoft Windows Update service. The Windows system driver search mechanism will download
and install the USB driver automatically from the Microsoft Windows Update service.
To evaluate with the Windows 7 and 8 operating systems, the u-blox GNSS standard driver (x64bit)
is needed which can be found in the u-center package.
3.2 Hardware installation
1. Connect the unit to a PC running Microsoft Windows. Options:
•USB: Connect via USB port (Micro-USB)
•UART: Connect via RS232. Set slide switch to I2C.
•SPI / I2C compliant DDC: Connect the corresponding pins (see Table 5 for pin description). Set slide
switch accordingly to SPI or I2C.
☞Press the RST button after changing the slide switch.
2. The device must always have power, either via USB or the V5_IN input on the front panel
connector.
3. Connect the GNSS antenna to the RF IN SMA jack and place the antenna in a location with good
sky view.
4. Start the u-center GNSS Evaluation Software and select the corresponding COM port and baud
rate.
☞Refer to the u-center User Guide [4] for more information.
3.3 Default interface settings
Parameter
Description
UART Port 1, input
38400 baud, 8 bits, no parity bit, 1 stop bit. UBX, NMEA and RTCM 3.3 input
protocols are enabled by default.
UART Port 1, output
38400 baud, 8 bits, no parity bit, 1 stop bit.
NMEA protocol with GGA, GLL, GSA, GSV, RMC, VTG, TXT, ZDA messages are
output by default. UBX and RTCM 3.3 protocols are enabled by default, but no
output messages are enabled by default.

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USB
Default messages activated as in UART1. Input/output protocols available as in
UART1.
I2C
Compatible with the I2C industry standard, available for communication with an
external host CPU or u-blox cellular modules, operated in slave mode only. Default
messages activated as in UART1. Input/output protocols available as in UART1.
Maximum bit rate 400 kb/s.
SPI
Allow communication to a host CPU, operated in slave mode only. Default
messages activated as in UART1. Input/output protocols available as in UART1.
SPI is not available unless D_SEL pin is set to low.
Table 3: Default configuration
☞Refer to the ZED-F9T Integration manual [3] for more information.

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4Device description
4.1 Interface connection and measurement
For connecting the EVK to a PC, use the included Micro-USB cable. Alternatively, a standard SUBD-9
cable can also be used. Additional measurement equipment can be connected to the front connector.
Figure 1: Connecting the unit for power supply and communication
4.2 Active antenna
EVK-F9T evaluation kits include an ANN-MB1 multi-band (L1/L5) active GNSS antenna with a 3-
meter cable and SMA connector.
The recommended maximum antenna supply current for active antennas is 15 mA.
4.3 Evaluation unit
Figure 2 shows the front and the rear panel of the EVK-F9T evaluation unit.
Front panel
Rear panel
Figure 2: EVK-F9T evaluation unit –front and rear panels
4.3.1 Antenna connector (RF IN)
An SMA female jack is available on the front side (see Figure 2) of the evaluation unit for connecting
an active GNSS antenna. A DC voltage of 3.3 V is provided to power the active antenna, and the RF
input is 3.3 V. The internal short circuit protection limits the maximum current to 60 mA. Note that
the 15-mA maximum supply current for the active antenna stays the same. This pin is also ESD
protected.
⚠The connector is only to be used with a GNSS antenna or simulator. Do not connect this equipment
to cable distribution systems.
4.3.2 Timepulse connector (TP1)
The evaluation board includes a time pulse function providing clock pulses with a configurable pulse
period, pulse length and polarity (rising or falling edge). Check the ZED-F9T Data sheet [1] for detailed
specifications of configurable values.

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An SMA female jack is available on the rear side (see Figure 2) of the evaluation unit which provides a
buffered timepulse1 signal for driving laboratory equipment.
☞J7 jumper can be shorted to allow higher output current when driving low impedance loads.
User must open the evaluation kit to access the J7 jumper as shown in the Figure 3.
Figure 3: EVK-F9T evaluation unit –PCB layout
4.3.3 USB connector
A USB V2.0 compatible serial port is featured for data communication and power supply.
4.3.4 D9 connector (RS232)
The evaluation unit includes an RS232 port for serial communication that is compatible with PC serial
ports. The D9 connector can only have the UART 1 input.
Connect using a straight RS232 serial cable with male and female connectors to the port on your PC.
The maximum cable length is 3 meters. To configure the RS232 port, use the CFG-UART1 command
in the u-center application. The maximum operating baud rate is 921.6 kBaud. If you are using a USB
to RS232 adaptor cable, you can connect it directly to the evaluation kit RS232 port.
The 9-pin D-SUB female connector is assigned as listed in Table 4:
Pin Nr.
Assignment
1
Timepulse 1 output (RS232 levels)
2
TXD, GNSS Transmit Data, serial data to DTE
3
RXD, GNSS Receive Data, serial data from DTE
4
Optional time-mark input (RS-232 levels) using EXTINT0 (internal jumper J6 fitment required)
5
GND
6
Timepulse 1 output (RS232 levels)
7
Not connected
8, 9
not connected
Table 4: SUB-D9 connector pin description for EVK-F9T
4.3.5 RST button
The RST button on the front panel resets the unit.

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☞The RESET pin will delete all information and trigger a cold start. It should only be used as a
recovery option.
4.3.6 Safe boot button
This is used to set the unit in safe boot mode. In this mode the receiver executes only minimal
functionality, such as updating new firmware into the flash memory. To set the receiver in safe boot
mode:
1. Press the BOOT button and keep holding it down.
2. Press the RST button.
3. Release the RST button.
4. Release the BOOT button.
5. If the UART interface is used, a training sequence must be sent to the receiver.
The training sequence is a transmission of 0x55 0x55 at a baud rate of 9600 baud. Wait for at
least 100 milliseconds before the interface is ready to accept commands.
4.3.7 Slide switch
Use the slide switch on the front panel to choose between I2C (and UART) and SPI communication
ports. You must reset the unit by pressing the RST button when the slide switch has been changed.
•I2C –In this selection the EVK operates with the UART (RS232 DB9 –rear panel or the 3.3 V
level TxD (MISO), RxD (MOSI) at the front panel). Also, the communication via 3.3 V DDC
interface (I2C) is selected.
•SPI –In this selection the EVK operates only with the SPI interface. The RS232 (DB9) port is
switched off.
4.3.8 Pin header
This 14-pin test-connector provides additional functionality to the EVK, allowing access to the
interface pins and an ability to measure the current used by the ZED-F9T module. All pins are ESD
protected.
Pin no.
Name
I/O
Level
Description
14
V5_IN
I
4.75 - 5.25 V
Power input –can be used instead of USB
13
GND
I
-
Common ground pin
12
CUR GPS1
O
5.0 V
Supply current measurement (Module current consumption) node 1. Current is
measured over a 1Ω1% tolerance resistor between pins 12 and 11. Pin 12
(CUR_GPS1) is at higher potential.
11
CUR GPS2
O
5.0 V
Supply current measurement (Module current consumption) node 2. See
description for pin 12.
10
NC
-
-
Reserved (the pin is reserved for floating, and the customer should not connect
any input to the pin)
9
EXTINT2
O
External interrupt 2 or time-mark 2 input (straight connected to the module
pins)
8
TIMEPULSE 1
O
3.3V
Output signal for the timepulse1 signal
7
EXTINT
I
3.3 V
External interrupt or time-mark input (connected directly to the module pins)
6
TIMEPULSE 2
O
3.3 V
Output signal for the timepulse2 signal
5
SDA / CS
I/O
3.3 V
If slide switch on I2C, the DDC interface is selected; Function: data input /
output
If slide switch on SPI, the SPI interface is selected; chip select input –LOW
ACTIVE

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4
SCL / SCK
I/O
3.3 V
Clock input / output (signals are pulled up and then straight to the module)
3
TxD / MISO
I/O
3.3 V
If slide switch on I2C, the DDC interface is selected / UART TxD (3.3 V level)
If slide switch on SPI, the SPI interface is selected; Master in Slave out (MISO)
2
RxD / MOSI
I/O
3.3 V
If slide switch on I2C, the DDC interface is selected / UART RxD (3.3V Level)
If slide switch on SPI, the SPI interface is selected; Master out Slave in (MOSI)
1
GND
I
-
Common ground pin
Table 5: Connector pin description for EVK-F9T (pins numbered from right to left on the front panel)
For accurate measurements, it is recommended to use a cable of at most 1 meter in length. Figure 4
shows an example of a power supply connected to the test connector by using standard adapter
cables from the manufacturer Hirschmann. Table 6 shows an example for overall current
measurement. When connecting the 3.3 V digital interfaces RS232, SPI and DDC to your application,
a cable length of less than 25 cm is recommended.
Figure 4: Example 5V DC power supply
4.3.9 LED
On the front panel of the unit, a single blue LED shows the timepulse 1 signal. The timepulse signal is
configurable, see the Interface description [2] for details.
4.3.10 EXT connector
This is a 6-pin connector in which pin 2 is connected directly to the GEOFENCE_STAT signal. Pin 4
and pin 5 are connected directly from RXD2 and TXD2 of the module, respectively.
TXD2 and RXD2 (UART2) can be used for correction data and NMEA messages.
Pins 3 and 6 are connected to GND.
Pin Nr.
Assignment
1
Common ground pin
2
GEOFENCE_STAT
3
GND
4
RXD2
5
TXD2
6
GND
Table 6: EXT connector pin details
V5_IN
GND
GND
V5_IN
Hirschmann
Part Nr.: 934160100

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5GNSS current measurement
At start-up, the receiver starts in acquisition state to search for available satellites and to download
GNSS orbital data, i.e., ephemeris and almanac. Once the data has been downloaded, the receiver
enters tracking state. In continuous operation, the receiver typically remains in tracking state once
entering it. The current consumption reduces when the receiver enters the tracking state. The time
required to enter tracking mode can be reduced by downloading aiding data from the AssistNow™
Online service.
To measure the total GNSS supply current with EVK-F9T, follow these steps:
1. Power up EVK-F9T.
2. Connect a true RMS voltmeter across CUR GPS1 (pin 12) and CUR GPS2 (pin 13) of the 14-pin
connector.
3. Read the voltage (and average if necessary) on the voltmeter and convert to current (1 mV equals
1 mA).
4. Perform the test with good signals and clear sky view to ensure that the receiver can acquire the
satellite signals.
☞The total GNSS current includes the internal LNA, SPI flash and TCXO.
For more details see the schematic in Figure .
Figure 5: Example –tracking current measurement
Hirschmann
Part No.: 934160100
P1A (VCC)
P1B
P1B
P1A (VCC)

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6Block diagram
Figure 6: EVK-F9T block diagram

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7Board layout
Figure shows the EVK-F9T board layout. See Table 7 for the component list of the EVB.
Figure 7: EVB-F9T layout
Part
Description
A1
GNSS RECEIVER U-BLOX ZED-F9T-10B -40/+85C
C1 C2 C4 C6 C8 C9
CAP CER X5R 0402 TY 1U0 10% 6.3V
C3
CAP CER X5R 1210 10U 10% 10V
C5
CAP CER X7R 0402 10N 10% 16V -55/+125C
C7
CAP CER COG 0402 47P 5% 25V
C10 C11 C12 C13 C14 C15 C16
C17 C18 C19 C20
CAP CER X5R 0402 100N 10% 50V
C21 C22 C23
CAP CER X7R 0603 6.3V -55/+125 1U 10% 6.3V -55/+125C
C24 C25 C26
CAP CER X5R 0603 10U 20% 6.3V
D1 D2 D3 D4 D5 D7 D8 D9 D10 D11
D12
VARISTOR BOURNS MLE SERIES CG0402MLE-18G 18V

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D6
USB DATA LINE PROTECTION ST USBLC6-2SC6 SOT23-6
D13 D14
SURFACE MOUNT SCHOTTKY BARRIER RECTIFIER SS14 1A -55/+125C
D15
LED OSRAM HYPER MINI TOPLED LB M673-L1N2-35 BLUE 0.02A
D16 D17
ESD PROTECTION FOR HIGH-SPEED LINES, TYCO, 0.25PF, PESD0402-140 -
55/+125C
J1
CON SMA THT RIGHT ANGLE JACK 18MM LENGTH
J2
14PIN 90° 2.54MM PITCH DISCONNECTABLE CRIMP CONNECTOR -40/+85C
J3
6PIN 90° 2.54MM PITCH DISCONNECTABLE CRIMP CONNECTOR -40/+85C
J4
CON USB RECEPTACLE MICRO B TYPE SMD-MOLEX 47346-0001-TID60001597 30V
1A
J5
CON SMA SMD STRAIGHT JACK 11.4MM HEIGHT WITHOUT WASHER AND NUT
J6
9 POLE SUBD CONNECTOR FEMALE
J7
1-ROWS TH-PCB CONNECTOR 2MM GRID 2PINS 0.50MM SQUARE 3.50MM
L1
IND MURATA LQG15H 0402 47N 5% 0.2A
Q1
COMPLEMENTARY N- AND P-CHANNEL 20V (D-S) MOSFET VISHAY Si1016 SC89-6
R3 R4
RES THICK FILM CHIP 0402 27R 5% YAGEO 27R 5% 0.063W -55/+155C
R5
RES THICK FILM CHIP 0402 10K 5% 0.1W
R6 R7 R8 R9 R10 R15 R16
RES THICK FILM CHIP 0402 100K 1% 0.063W
R11 R12
RES THICK FILM CHIP 0402 100R 5% 0.1W
R13
RES THICK FILM CHIP 0805 10R 5% 0.125W -55/+155C
R14
RES THICK FILM CHIP 0402 1K0 1% 0.063W
R17 R22
RES THICK FILM CHIP 0201 51R 1% 0.05W
R18
RES THICK FILM CHIP 0402 CURRENT SENSE 1R 1% 1.1V -55/+125C
R25
RES THICK FILM CHIP 0402 39R 5% 0.063W -55/+125C
S1 S2
SWITCH SPST ON 1POL TYCO -40/+85C
S3
2 WAY SUB-MINIATURE SLIDE SWITCH SMD JS SERIES - SPDT -40/+85C
U1 U2
TINY LOGIC ULP-A 2-INPUT AND GATE 1.45X1.0 6-LEAD MICROPAK -40/+85C
U3 U4
TINY LOGIC UHS BUFFER OE ACTIVE HIGH FAIRCHILD NC7SZ126 SOT23-5
U5
RS-232 TRANSCEIVER 1MBIT 3-5,5VOLT TRSF3223 - VQFN20 5.5V 5.5V -40/+85C
U6
PRECISION RAIL TO RAIL OP AMP LINEAR LT6000 DCB
U7
TRIPLE BUFFER WITH OPEN-DRAIN OUTPUT 74LVC3G07 -40/+125C
U8 U9 U13 U14
TINY LOGIC UHS BUFFER OE_N ACTIVE LOW FAIRCHILD NC7SZ125 SC70
U10 U11 U12
LOW DROPOUT REGULATOR ON SEMI NCV8705 WDFN6 0.5A 3.3V
Table 7: EVB-F9T component list

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8Schematic
Figure 8: Schematic EVK-F9T: GNSS, Antenna supervisor, Supply

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Figure 9: Schematic EVK-F9T: Connectors

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9Troubleshooting
My application (e.g. u-center) does not receive anything
Check whether the blue LED on the evaluation unit is blinking. Also make sure that the USB cable is
properly connected to the evaluation unit and the PC. By default, the evaluation unit outputs NMEA
protocol on Serial Port 1, or on the USB.
My application (e.g. u-center) does not receive all messages
When using UART, make sure the baud rate is sufficient. If the baud rate is insufficient, GNSS
receivers based on u-blox F9 GNSS technology will skip excessive messages. Some serial port
cards/adapters (i.e. USB to RS232 converter) frequently generate errors. If a communication error
occurs while u-center receives a message, the message will be discarded.
My application (e.g. u-center) loses the connection to the GNSS receiver
u-blox F9 positioning technology and u-center both have an autobauding feature. If frequent
communication errors occur (e.g. due to problems with the serial port), the connection may be lost.
This happens because u-center and the GNSS receiver both autonomously try to adjust the baud rate.
Do not enable the u-center autobauding if the GNSS receiver has the autobauding flag enabled.
The COM port does not send any messages
Be sure that the slide switch at the front panel is set to I2C and not SPI. In SPI mode the RS232 pins
on the DB9 connector are switched off and the RxD and TxD output at the front panel are used for SPI
(MISO, MOSI).
☞After changing the slide switch, always reset the EVK; if it is not reset, the change will not take
place.
Some COM ports are not shown in the port list of my application (e.g. u-center)
Only the COM ports that are available on your computer will show up in the COM port drop-down list.
If a COM Port is gray, another application running on this computer is using it.
The position is off by a few dozen meters
u-blox F9 GNSS technology starts up with the WGS84 standard GNSS datum. If your application
expects a different datum, you will most likely find the positions to be off by a few dozen meters. Do
not forget to check the calibration of u-center map files.
The position is off by hundreds of meters
Position drift may also occur when almanac navigation is enabled. The satellite orbit information
retrieved from an almanac is much less accurate than the information retrieved from the ephemeris.
With an almanac only solution, the position will only have an accuracy of a few kilometers, but it may
start up faster or still navigate in areas with obscured visibility when the ephemeris from one or
several satellites have not yet been received. The almanac information is NOT used for calculating a
position, if valid ephemeris information is present, regardless of the setting of this flag.
In NMEA protocol, position solutions with high deviation (e.g. due to enabling almanac navigation) can
be filtered with the Position Accuracy Mask. UBX protocol does not directly support this since it
provides a position accuracy estimation, which allows the user to filter the position according to his
requirements. However, the ‘Position within Limits’ flag of the UBX-NAV-STATUS message indicates
whether the configured thresholds (i.e. P Accuracy Mask and PDOP) are exceeded.
TTFF times at startup are much longer than specified
At startup (after the first position fix), the GNSS receiver performs an RTC calibration to have an
accurate internal time source. A calibrated RTC is required to achieve minimal startup time.

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Before shutting down the receiver externally, check the status in MON-HW in field ‘Real Time Clock
Status’. Do not shut down the receiver if the RTC is not calibrated.
The EVK-F9T does not meet the TTFF specification
Make sure the antenna has a good sky view. An obstructed view leads to prolonged startup times. In
a well-designed system, the average of the C/N0 ratio of high elevation satellites should be in the
range of 40 dBHz to about 50 dBHz. With a standard off-the-shelf active antenna, 47 dBHz should
easily be achieved. Low C/N0 values lead to a prolonged startup time.
The EVK-F9T does not preserve the configuration in case of reset
u-blox F9 GNSS technology uses a slightly different concept than most other GNSS receivers do.
Settings are initially stored to volatile memory. In order to save them permanently, sending a second
command is required. This allows testing the new settings and reverting to the old settings by
resetting the receiver if the new settings are not good. This provides safety, as it is no longer possible
to accidentally program a bad configuration (e.g. disabling the main communication port).
The EVK-F9T does not work properly when connected with a GNSS simulator
When using an EVK together with a GNSS simulator, pay attention to proper handling of the EVK. A
GNSS receiver is designed for real-life use, i.e. time is always moving forward. By using a GNSS
simulator, the user can change scenarios, which enables jumping backwards in time. This can have
serious side effects on the performance of GNSS receivers.
The solution is to configure the GPS week rollover to 1200, which corresponds to Jan 2003. Then,
issue the cold start command before every simulator test to avoid receiver confusion due to the time
jumps.
Power save mode and USB
For communication in power save mode, use the RS232.

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10 Common evaluation pitfalls
•A parameter may have the same name but a different definition. GNSS receivers may have a
similar size, price and power consumption, but can still have different functionalities (e.g. no
support for passive antennas, different temperature range). Also, the definitions of hot, warm,
and cold start times may differ between suppliers.
•Verify design-critical parameters; do not base a decision on unconfirmed numbers from data
sheets.
•Try to use identical or at least similar settings when comparing the GNSS performance of different
receivers.
•Data that has not been recorded at the same time and the same place should not be compared.
The satellite constellation, the number of visible satellites, and the sky view might have been
different.
•Do not compare momentary measurements. GNSS is a non-deterministic system. The satellite
constellation changes constantly. Atmospheric effects (i.e. dawn and dusk) have an impact on
signal travel time. The position of the GNSS receiver is typically not the same between two tests.
Comparative tests should therefore be conducted in parallel by using one antenna and a signal
splitter; statistical tests shall be run for 24 hours.
•Monitor the carrier-to-noise ratio. The average C/N0 ratio of the high elevation satellites should be
between 40 dBHz and about 50 dBHz. A low C/N0 ratio will result in a prolonged TTFF and more
position drift.
•When comparing receivers side by side, make sure that all receivers have the same signal levels.
The best way to achieve this is by using a signal splitter. Comparing results measured with
different antenna types (with different sensitivity) will lead to incorrect conclusions.
•Try to feed the same signal to all receivers in parallel (i.e. through a splitter); the receivers will not
have the same sky view otherwise. Even small differences can have an impact on the accuracy.
One additional satellite can lead to a lower DOP and less position drift.
•When doing reacquisition tests, cover the antenna to block the sky view. Do not unplug the
antenna since the u-blox F9 positioning technology continuously performs a noise calibration on
idle channels.