SE867-AGPS User Guide
1VV0300860 Rev. 3 - 2010-05-10
Reproduction forbidden without Telit Communications S.p.A. written authorization - All Rights Reserved
page 21 of 69
6.
ions, it is crucial to
is of paramount importance designing the RF
path according to the best practices as far as the EMC/EMI and propagation aspects are
concerned. Hence, the below requirements and guidelines have to be read and followed
h-performing application design.
6.1.
gain > 16dB and a
der to achieve this
wed, even if the
gain in the active
antenna avoiding the LNA when such an antenna is available.
Increasing path gain far beyond 16 dB is not suggested because after this threshold,
the improvem
m a gain increase are limited and chances
ues incr
trating the whole gain in the antenna the
m allowed gain
e table below active and passive antenna
RF path and antenna
When dealing with very low RF signal, as in the case of GPS applicat
have a proper PCB layout. In particular it
carefully to have a hig
RF design guidlines
The SE867-AGPS module requires an external RF path with a net
noise figure < 1.5dB in order to achieve the best performances. In or
gain designs with external LNA and/or active antenna are allo
suggestion for better RF performances is to concentrate the path
ents in sensitivity deriving fro
of jamming iss
ease. When concen
maximu
for it is 30dB. In th
required features are reported.
ANTENNA REQUIREMENTS
Central frequency
1575.42 MHz (GPS L1)
Bandwidth
1.023MHz
Amplification (active antenna
25dB typ. (30dB max)
only)
Noise figure (active
antenna only)
< 1.5dB
Impedance [Ohm]
50
Supply voltage (active
Depends on customer design
antenna only)
Coupling with other signals is not allowed
When choosing an active antenna gain the cable loss must be taken into account in
order to get the desired RF path net gain. Furthermore, please note that when
using a passive antenna the external LNA is mandatory.
