LE910Cx
Hardware User Guide
1VV0301298 Rev. 1.05 - 2017-06-18
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7.5.
GNSS Antenna Requirements
LE910Cx supports an active antenna.
It is recommended to use antennas as follow:
•
An external active antenna (GPS only)
•
An external active antenna plus GNSS pre-filter
NOTE:
The external GNSS pre-filter is required for the GLONASS application.
The GNSS pre-filter must meet the following requirements:
Source and load impedance = 50 Ohm
•
Insertion loss (1575.42–1576.42 MHz) = 1.4 dB (Max)
•
Insertion loss (1565.42–1585.42 MHz) = 2.0 dB (Max)
•
Insertion loss (1597.5515–1605.886 MHz) = 2.0 dB (Max)
NOTE:
It is recommended to add a DC block to the customer’s GPS application to prevent damage to the
LE910Cx module due to unwanted DC voltage.
7.5.1.
Combined GNSS Antenna
The use of a combined RF/GNSS antenna is NOT recommended. This solution can generate an
extremely poor GNSS reception. In addition, the combination of antennas requires an additional
diplexer, which adds significant power loss in the RF path.
7.5.2.
Linear and Patch GNSS Antenna
Using this type of antenna introduces at least 3 dB of loss compared to a circularly polarized (CP)
antenna. Having a spherical gain response instead of a hemispherical gain response can aggravate
the multipath behavior and create poor position accuracy.
7.5.3.
Front End Design Considerations
Since there is no antenna connector on the LE910Cx module, the antenna must be connected to
the LE910Cx through the PCB to the antenna pad.
If the antenna is not directly connected at the antenna pad of the LE910Cx, a PCB line is required.
This line of transmission must meet the following requirements: