First, I am sorry, I want to give you the score but I really have no value to give, so please forgive me for the heroes to help, this is the mobile communication technology course is our examination of the contents please help
The primary power supply usually refers to the input power, such as the 220V ac,The two power supply generally refers to the power supply that is converted from the input power supply.
There is now useful to the two switching power supply, that is, switching power supply, a 220V power input, and then a 48V DC power to balance and reserve power (battery) use.
Primary power is the direct power supply access 220V, input to the settings to ensure the normal operation of the settings!Two power can be understood from the literal, is second times the input to the equipment in the battery using most two power communication equipment now the way is the power 220V input transformer (or constant pressure) for DC output to the equipment used in.
