When passing through a tunnel, accurate positioning is not possible. For modules with inertial navigation, the position information is calculated based on the previous location data using the gyroscope. Time information can be obtained through self-timing, but the current firmware does not have this functionality.

When passing through a tunnel, accurate positioning is not possible. For modules with inertial navigation, the position information is calculated based on the previous location data using the gyroscope. Time information can be obtained through self-timing, but the current firmware does not have this functionality.

When passing through a tunnel, accurate positioning is not possible. For modules with inertial navigation, the position information is calculated based on the previous location data using the gyroscope. Time information can be obtained through self-timing, but the current firmware does not have this functionality.

AT+RTCM=UART1,1. The dual-frequency module has two UARTs. You can configure one of them to receive RTCM data for use as a base station.The base station also performs coordinate calibration, which can be achieved by using AT+BASE_LLH=0,0,0 for adaptive coordinates.

RTCM is raw data in hexadecimal format, not processed or formatted according to any standard. NMEA is a standardized output format in ASCII format, providing processed PVT-related information.