MAX-M5Q - Hardware Integration Manual
FTX-HW-13008
Objective Specification
Design
Page 23 of 40
Figure 16: External active antenna control
For recommended parts, see section 4.3.
4.2.3
Design with GLONASS / GPS active antenna
The Russian GLONASS satellite system is an alternative system to the US-based Global Positioning System (GPS).
u-blox 7 modules can receive and process GLONASS signals. GLONASS and GPS satellite signals are not
transmitted at the same frequency (as seen in Figure 17). In existing designs that were only intended for GPS
reception, the RF path has to be modified (the LNA, filter, and antenna) accordingly to let both signals pass.
Figure 17: GPS & GLONASS SAW filter
Usually an active GPS antenna includes a GPS band pass filter, which may filter out the GLONASS signal (see
Figure 17). For this reason, make sure that the filter in the active antenna is wide enough to let the GPS and
GLONASS signals pass. Use a good performance GPS & GLONASS active antenna (for recommended
components see section 1.1.1880621787).
In a combined GPS & GLONASS antenna, be sure to tune the antenna for receiving both signals. In addition, any
internal filter has a larger bandwidth to provide optimal GPS & GLONASS signal reception (see Figure 17).
Use a good performance GPS & GLONASS active antenna (for recommended components see section
1.1.1880621787).
