ZED-F9P-Integration Manual
UBX-18010802 - R02
8 Design Page 101 of 114
Advance Information
8.9.3 Antenna/ RF input
Check RF input requirements and schematic:
• With the ZED-F9P GNSS module, an active antenna meeting our antenna requirements is
mandatory is to achieve the performance values as written in the ZED-F9P datasheet.
• Implementing your own antenna design with a suitable antenna element (stacked patch or helix)
and the required RF components is complex and should not be carried out unless under the strict
guidance of the antenna supplier to meet our requirements.The risk in not meeting the required
RTK performance is a factor.
• An OEM active antenna module that meets our requirements should be used if there is a need
to integrate the antenna.
• The total maximum noise figure including external LNA (or the LNA in the active antenna) should
be around 2 dB.
• Ensure active antenna gain is ideally between 30 - 40 dB gain.
• Make sure the antenna is not placed close to noisy parts of the circuitry and not facing noisy
parts. (e.g. micro-controller, display, etc.)
• For RTK operation good signals levels above 40 CNO average are required.There is a requirement
on the minimum number and type of GNSS satellites being received in a typical environment
to achieve fixed RTK performance: Signals above 35 CNO (minimum) for a minimum of 6 GPS
satellites. The same is true for any single system that is enabled (Beidou, GLONASS). The same
is true if a multi constellation configuration is used. A single system being received must have 6
satellites at the minimum signal level and quality to achieve RTK Fixed status.
• If a patch type antenna used an antenna ground plane minimum 100 - 150 mm in diameter are
required.
• Ensure antenna is L1 and L2 band specified.
• Ensure antenna element gain is between 2 - 3 dBic typical for L1 and L2 bands.
• Ensure the group delay variation including active antenna is 10 ns max @ each GNSS system
bandwidth. Note: Inter-signal requirement 50 ns max.
• ESD protection on the RF input is mandatory.
• Bias-t inductor must be L1 and L2 band frequency selected. 120 nH typical.
• Ensure RF trace is tuned for 50 Ω at 1575 MHz to ensure L1 and L2 band width.
8.9.4 ZED-F9P ground pads
Ensure the ground pads under the module are connected to ground.
8.9.5 Schematic design-in.
For a minimal design with the ZED-F9P GNSS modules, the following functions and pins need to be
considered:
• Connect the power supply to VCC and V_BCKP.
• V_USB: If USB is used connect V_USB to receiver VCC.
• If USB is not used connect V_USB to ground.
• Ensure an optimal ground connection to all ground pins of the ZED-F9P GNSS modules.
• Choose the required serial communication interfaces (UART, USB, SPI or DDC) and connect the
appropriate pins to your application
• If you need hot or warm start in your application, connect a Backup Battery to V_BCKP.
• Antenna bias is required, see ZED-F9P antenna bias section.
8.9.6 Pin assignment
Pin No Name I/O Description Remark
1 GND - Ground Outer ground pin
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