u-blox MAX-7 Series User Manual

MAX-7 / NEO-7 / LEA-7 - Hardware Integration Manual
GPS.G7-HW-11006-1 Design
Page 33 of 55
3.4.4 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 30
). 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 30: GPS & GLONASS SAW filter
Usually an active GPS antenna includes a GPS band pass filter, which may filter out the GLONASS signal (see
Figure 30). 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 3.5.1).
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 30).
Use a good performance GPS & GLONASS active antenna (for recommended components see section
3.5.1).

u-blox MAX-7 Series Specifications

General

Brand	u-blox
Model	MAX-7 Series
Category	GPS
Language	English