Smart Machine Smart Decision
SIM7000 _Hardware Design _V1.00 2017-05-23
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. NMEA sentences can be obtained through UART or USB
automatically. NMEA sentences include GSV, GGA, RMC, GSA, and VTG. Before using GNSS,
user should configure SIM7000 in proper operating mode by AT command. Please refer to related
documents for details. SIM7000 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 [24] 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.
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