L
LE920 Hardware User Guide
1vv0301026 Rev.0 - draft4 – 2013-05-
Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved.
Page 45 of 76
The second Rx antenna should not be located in the close vicinity of main antenna. In order to
improve Diversity Gain, Isolation and reduce mutual interaction, the two antennas should be
located at the maximum reciprocal distance possible, taking into consideration the available
space into the application.
6.5.
GPS/GNSS Antenna Requirements
LE920 supports only passive antenna and includes an internal LNA inside (13.5dB gain typ.).
It is recommended to use antennas as follow:
x
An external passive antenna (GPS only)
x
An external passive antenna, GNSS pre-Filter
NOTE:
The external GNSS pre-Filter shall be required for GLONASS application.
GNSS pre-Filter requirement shall fulfill the following requirements.
z
Source and Load Impedance = 50Ohm
z
Insertion Loss (1575.42 – 1576.42MHz) = 1.4dB (Max)
z
Insertion Loss (1565.42 – 1585.42MHz) = 1.4dB (Max)
z
Insertion Loss (1597.5515 – 1605.886MHZ) = 2.0dB (Max)
WARNING:
The LE920 software is implemented differently depending on the configurations of an
external device. Please refer to the AT command User Guide in detail.
6.5.1.
Combined GPS/GNSS Antenna
The use of combined RF/GPS/GNSS antenna is NOT recommended. This solution could
generate extremely poor GPS/GNSS reception and also the combined antenna requires
additional diplexer and adds a loss in the RF route.
In addition, the combination of antennas requires an additional diplexer, which adds
significant power losses in the RF path.
