GN-02B RTK module test tool：
Use tools to test and set up GN-02B GNSS module
Set 5HZ output command: $cfgnav,200,,,,
Set the baud rate and save:
Set the baud rate to 38400 and save the command: $cfgprt,,38400,,;cfgsave
Set the baud rate to 9600 and save the command: $cfgprt,,9600,,;cfgsave
Set the baud rate to 4800 and save the command: $cfgprt,,4800,,;cfgsave