Patch Panel
Also known as a jackfield or patch bay, a patch panel is a panel containing a series of connection points for electronic equipment. This allows equipment to be inter-connected in various configurations.
Common applications for patch panels include:
- Audio and video production studios
- Communications networks
- Computer networks
The patch panel illustrated here is from a television OB truck. It includes audio connections (the black racks at the top) and video connections (the BNC sockets). Patches can be made with cables or U-link connectors.
The audio patches connect sources such as microphones to the mixing desk, VT machines, etc. The video patches connect cameras and VT machines to the vision mixer and other destinations.
The ability to change patches means that sources can be routed to different destinations, including processing equipment, testing stations, etc. If a piece of equipment fails, patches can be re-routed to by-pass it. This gives the operation a great deal of flexibility to adapt to new situations or problems.
Many patch panels use a system called normalling. In this system, rows of jacks are arranged in pairs with a upper and lower row as per the example above. In each pair of jacks, the upper jack is connected to the lower jack. This is called a normalled connection, meaning the signal will normally flow from the upper jack to the lower one if no cable is plugged in. When a cable is plugged into the upper jack, the connection is broken and the signal flows into the cable instead.