LEA-6 / NEO-6 / MAX-6 - Hardware Integration Manual
UBX-14054794
Production Information
Design-in
Page 25 of 85
2.2.2
GLONASS HW design recommendations (LEA-6N, LEA-6H-0-002
8
)
The Russian GLONASS satellite system is an alternative system to the US-based Global Positioning System (GPS).
LEA-6N modules can receive and process GLONASS signals. LEA-6H-0-002 modules are GLONASS ready and are
capable of receiving and processing GLONASS signals via a firmware upgrade8.
LEA-6N and LEA-6H-0-002 designs for GLONASS require a wide RF path. Ensure that the antenna and external
SAW filter are sufficient to allow GLONASS & GPS signals to pass (see Figure 16).
Use an active GLONASS antenna. For best performance with passive antenna designs use an external LNA. (See
section 2.2.2.7.
)
LEA-6N and LEA-6H-0-002 modules are pin compatible.
2.2.2.1
Wide RF path
As seen in
Figure 16, the GLONASS / GPS satellite signals are not at the same frequency. For this reason the RF
path, LNA, filter, and antenna must be modified accordingly to let both signals pass.
2.2.2.2
Filter
Use a GPS & GLONASS SAW filter (see Figure 16) that lets both GPS and GLONASS signals pass. (See the
recommended parts list in section 3.3.9.)
If an active antenna is used, make sure that any filter inside is wide enough.
Figure 16: GPS & GLONASS SAW filter
2.2.2.3
Active antenna
Usually an active GPS antenna includes a GPS band pass filter which might filter out the GLONASS signal (see
Figure 16). For this reason make sure that the filter in the active antenna is wide enough to let the GPS and
GLONASS signals pass.
In combined GPS & GLONASS antennas, the antenna has to be tuned to receive both signals and the filter has a
larger bandwidth to provide optimal GPS & GLONASS signal reception (see Figure 16).
Use a good performance GPS & GLONASS active antenna (for recommended components see section
3.3.9.1).
Figure 17: GPS & GLONASS active antenna
8
Requires firmware upgrade with FW1.00 GLONASS, GPS & QZSS Flash firmware image, available from u-blox.
