User's Manual
DE910 Series Hardware User Guide
1vv0300951 Rev.9 – 2015-05-11
Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights
Reserved. Page 41 of 77
6.3. GNSS Antenna Requirements
The use of an active GNSS antenna is required to achieve better performance.
The module is provided with a Digital Output signal to enable the external LNA (pad R7).
Parameter Min Max
Output high level
1.35V 1.8V
Output low level
0.0V 0.45V
6.3.1. Combined GNSS Antenna
The use of combined CDMA/GNSS antenna is not recommended. This solution could
generate extremely poor GNSS reception and also the combined antenna requires an
additional diplexer and adds a loss in the RF route.
6.3.2. Linear and Patch GNSS Antenna
Using this type of antenna introduces at least 3dB of loss if compared to a circularly polarized
(CP) antenna. Having a spherical gain response instead of a hemispherical gain response
could aggravate the multipath behaviour & create poor position accuracy.
6.3.3. The Design Considerations to enhanced
GNSS performance
Depending on the characteristics and requirements unique to the customer’s designs, the use
of an external LNA or an external active antenna may be required to achieve best
performance.
The optional external LNA should be dimensioned to avoid an excessive LNA gain that can
introduce jamming, spurious, degrade IIP3, and saturate the receiver.
The configurations of an external device must fulfill the following requirements:
An external passive antenna (GPS only)
An external active antenna (GPS or GNSS)
An external passive antenna, GNSS pre-Filter , and GNSS LNA (GPS or GNSS)