The MGS12i is a GPS device with one end input and two end outputs, which usually divides the received signal from the active GPS receiving antenna into two outputs for GPS receiving equipment.
Both outputs of the MGS12i are powered on at the same time. The power divider internally selects the port for powering the active GPS antenna by comparing the voltages.
When the voltage values of the two output ports are different, the higher voltage port will be used to supply power to the active GPS antenna. The other port will have a 200 Ohm DC load to simulate any receiver antenna connected to this port DC loss.
When the two output ports have the same voltage value, the J1 port is used by default for power supply. The J2 port will have a 200 Ohm DC load.