MAX-7 / NEO-7 - Hardware Integration Manual
UBX-13003704
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R09
Production Information
Design
Page
30 of 52
3.4.3.5
External active antenna control (NEO-7N, MAX-7Q, MAX-7C)
The ANT_ON signal can be used to turn on and off an external LNA. This reduces power consumption in Power
Save Mode (Backup mode).
Figure 26: External active antenna control (MAX-7Q / MAX-7C)
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 27). 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 27: GPS & GLONASS SAW filter
Usually an active GPS antenna includes a GPS band pass filter, which may filter out the GLONASS signal (see
Figure 27). 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.
Use a good performance GPS & GLONASS active antenna (for recommended components see section
3.5.1).
