Gps Application Interface; Gps Operating Modes - SimCom SIM808 Hardware Design

only can be got after the antenna tuning. Usually, matching components' value is provided by antenna vendor, the
default value of R101 and R102 are 0Ω, and reserve the place of C101 and C102 without soldering.
The RF test connector in Figure 50 is used for conducted RF performance test, and should be placed as close as
possible to the module's RF_ANT pad. The traces in bold type should be treated as 50Ω impedance controlled
line in PCB layout. For details about radio frequency trace layout, please refer to document [9].

5 GPS Application Interface

SIM808 provide a high-performance L1 GPS solution for cellular handset applications. The solution offers
best-in-class acquisition and tracking sensitivity, Time-To-First-Fix (TTFF) and accuracy. The GPS engine
supports both fully-autonomous operations for use in handheld consumer navigation devices and other
standalone navigation systems.
The module supports GPS, QZSS, SBAS ranging (WAAS, EGNOS, GAGAN, MSAS).
The GPS NMEA information is output by serial port. The default baud rate is 115200bps.
The GPS engine is controlled by GSM engine, so when it is necessary to run GPS，the GSM engine must be
powered on and not in SLEEP mode.
All the GPS function is controlled by AT command via serial port. The GPS functions of AT commands are listed
in the following table.
Table 37: AT Commands for GPS function
Command
AT+CGPSPWR
AT+CGPSRST
AT+CGPSSTATUS
AT+CGPSOUT
AT+CGPSINF
AT+CGPSIPR
For details of these AT command, please refer to document [1].
5.1

GPS Operating Modes

GPS has two operating modes which can be controlled by AT command.
Active mode: GPS is active as a GPS receiver. The GPS engine will automatically acquire and track GPS
satellites.
Power down mode: The GPS engine will be set into this mode by sending AT command "AT+CGPSPWR=0". In
this mode the internal power supply for GPS will be shutdown, and the current consumption is very low. The last
position, current time and ephemeris data will be stored in the GSM host memory.
SIM808_Hardware Design_V1.00
Description
GPS power control
GPS mode reset (hot/warm/cold)
Get current GPS status
GPS NMEA data output control
Get current GPS location info
Set GPS NMEA output UART bps
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Smart Machine Smart Decision
2014.03.27