Video switchers accept multiple video inputs and control display-sequence switching from video sources such as cameras and video servers. Sequencing is often user-defined and varies in terms of dwell time, display order, and sequencing mode. Video switchers consist of a main control panel that serves as the user interface and a rack unit (RU) of printed circuit boards (PCB) that perform various functions based on user input. Standard devices are connected in parallel to existing control switches or use serial communication interfaces such as RS232 or RS422. Wireless products use infrared (IR) transceiver systems. Most video switchers support standard definition (SD) video, high definition (HD) video, or both SD and HD. Devices use 115 VAC or 230 VAC and provide programmable logic, digital signal processing (DP), four or more duplex-transceiver channels, and high-speed data transmission rates.
Performance specifications for video switchers include video inputs, video outputs, number of sequences, steps per sequence, and dwell time. Video inputs are the maximum number of video signals that can be received simultaneously from devices such as cameras. Video outputs are the maximum number of video signals that can be transmitted simultaneously to devices such as monitors. The number of sequences is the maximum number of programmable displays. Steps per sequence are the maximum number of individual display steps for a single sequence. Dwell time is the time spent on each image in the sequence. Typically, dwell time is user-programmable and measured across a range.
There are several mounting styles for video switchers. Desktop units are designed to sit atop a desk or work bench. Floor-standing or stand-alone devices often include a full casing or cabinet and an integral interface. Panel-mounted video switchers are designed to be bolted onto a wall, or into a cabinet or enclosure. Rack-mounted devices fit standard 19 in. telecommunications racks. Video switchers that mount on DIN rails are also available. DIN is an acronym for Deutsches Institut für Normung (DIN), a German national organization for standardization.
Video switchers offer variety of features. Alarm inputs allow devices to receive alarm or relay signals from other video equipment. Alarm outputs can produce digital, visual, or audible alarm signals. Some video switchers include a computer interface, audio capability, or multi-lingual programming. Other devices provide time/date stamping, and printer/logger outputs. Camera control capabilities allow users to perform functions such as pan, zoom, and tilt; and to use video switchers to turn cameras on and off.