Outside Broadcast ("OB") refers to any television or radio programme which is broadcast from a location away from the normal studio setting. The location doesn't actually have to be out-of-doors — the "outside" simply means "outside the studio".
Television outside broadcasts can be any size and complexity, from a single camera to dozens of cameras and staff. Generally, the term OB implies multi-camera coverage co-ordinated and directed from a mobile control room.
An "OB Unit" is a mobile production unit (with equipment and crew) which is able to travel to a location and provide broadcast coverage. A simple OB unit could include any of the following:
- A number of cameras (usually at least four)
- A mobile control room, staffed by a director, vision controller, sound operator and VT (videotape) operator
- Equipment and housing for a presentation area
- Transmission equipment
Events commonly covered by OB units include sports, concerts, ceremonies, etc. OB units may specialise in a particular area; for example, a motorsports OB unit would carry specialised camera equipment for in-car coverage and have staff which know this particular sport well.