Avoiding Ground Loops in Radar Signal Connections

When connecting an interface card (for example one of Cambridge Pixel’s HPx series of cards) to a radar or simulator, the possibility arises of ground loops. These can introduce noise into the signals, but more seriously they can permit large currents to flow into sensitive devices causing card failure (on either the sender or receiver side). This article explains the issues and describes the best practice for connections. There are typically several signals associated with a radar interface and these signals may be of different types. The specific situation that needs careful consideration is when a grounded signal source is used with a grounded signal receiver. The situation is shown below. The ground connection on the source and receiver is shown in red. In this configuration, the signal from the source has its negative side connected to the chassis ground. On the receiver, the negative input is also connected to chassis ground. The two separate ground points provides a path for spurious currents through induced voltages in the cable connecting the negative signals, and also in the ground path of each side. The signal being shown here could be video, trigger, ACP or ARP...