Signal grounding method should be used one point ground.
Signal grounding: in order to ensure that the signal has a stable reference potential and set the ground.
Signal circuit grounding purpose: in order to make electronic equipment work with a uniform reference potential, to avoid harmful electromagnetic interference, so that electronic equipment, stable and reliable work, electronic equipment in the signal circuit should be grounded, referred to as the signal ground. Here the "ground" can be the earth, but also can be the electronic equipment floor, metal casing or an equipotential surface.
Power ground: the system power supply zero potential public **** reference ground. As the power supply is often simultaneously supplied to the various units of the system, and the various units require the nature of the power supply and parameters may be very different, so it is necessary to ensure that the power supply stable and reliable work, but also to ensure that the other units work stably and reliably.
Power supply (electrical device) grounding, the main purpose: 1, to protect personal and equipment safety, to prevent damage to the insulation of electrical devices may be charged shell, people will be touched by the risk of electric shock; 2, the system operation needs, such as AC power system neutral grounding, DC system of the power supply positive or mid-point grounding.
Signal grounding and power grounding difference: 1. Signal grounding to protect the stable and reliable operation of the equipment; 2. Power grounding is not only to protect the safety, more importantly, to protect personal safety.