Specifications

Smart Machine Smart Decision

SIM7080G _Hardware Design _V1.03 46 2019-12-13

MODULE

GPS_ANT

GND

LNA

GNSS passive antenna

V_LNA

SAW

Figure 29: Passive antenna circuit (Default)

In above figures, the components C1, L1 and L2 are used for antenna matching.Usually, the values

of the components can only be achieved after antenna tuning and usually provided by antenna

vendor.C2 is used for DC blocking. L3 is the matching component of the external LNA, and the

value of L3 is determined by the LNA characteristic and PCB layout.Both VDD of active antenna

and V_LNA need external power supplies which should be considered according to active antenna

and LNA characteristic. LDO/DCDC is recommended to get lower current consuming by shutting

down active antennas and LNA when GNSS is not working.

GNSS can be tested by NMEA port. NMEAsentences can be obtained through UART or

USBautomatically. NMEA sentences include GSV, GGA, RMC, GSA, and VTG. Before using

GNSS, user should configure SIM7080G in proper operating mode by AT command. Please refer to

related documents for details. SIM7080G can also get position location information through AT

directly.

Note:

1. GNSS is closed by default and can be started by “AT+CGNSPWR=1”. The AT command has

two parameters, the first is on/off, and the second is GNSS mode. Default mode is standalone

mode.

AGPS mode needs more support from the mobile telecommunication network. Please refer to

document [21] for more details.

2. If the passive antenna is used, put the LNA close to the antenna.

3. Make sure there are no noise signals around GNSS antenna.