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 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.