Camera switchers are devices that allow CCTV system operators to switch between
cameras--either manually or automatically. Manual switchers, for example, enable operators
to periodically switch from one camera to another, as the need arises. This is the most
basic switcher available and certainly the most inexpensive type tobuy and maintain.
Sequential switchers, on the other hand, automatically switch between camera scenes,
allowing system operators to perform other tasks while they keep watch on certain areas of
a facility. This type of switcher, for example, allows operators to write reports, answer
the telephone and perform other duties at the same time that they observe camera scenes.
There are several types of sequential switchers that installers use.
Bridging Switchers - A Bridging switcher provides two
seperate monitor outputs. The first monitor typically is set to display only one of the
entire group of camera signals. The other monitor displays the other camera scenes in
ascending order.
Homing Switchers - Homing switchers are similar to Bridging switchers in that each of the two monitors can be operated seperately. However, where the Bridging switcher channels one particular camera to a second monitor--without including it in the sequentially-observed camera images, the Homing switcher allows users to pick one of the normally sequenced scenes to view on a second monitor. This arrangement is especially useful when a particular entrance or area of a building requires special treatment.
Looping Switchers - Looping switchers also provide a seperate 75-ohm output for each camera input. This allows installers to route particular cameras to another switcher, monitor, or time-lapse tape recorder.
Alarming Switchers - Automated switching using an alarm switcher makes it possible to focus on a particular area in a mechanized fashion without user intervention. This method usually begins with either a set of screw terminals or some other contact method to which any normally-open, dry-contact switch or relay output is connected. Alarming switchers, in short, enable users to automatically call up a particular camera scene when a detector in the vicinity of the camera is violated.
Combination Switchers - CCTV manufacturers have also engineered a line of switchers that have many of the characteristics of two or more of the above switcher types. This approach enables installers and their clients the luxury of mixing and matching features without getting stuck with features that no one wants.
Microprocessor-based Matrix Switchers - Microprocessors
that utilize LSI (Large-Scale Integration) and VLSI (Very-Large-Scale Integration)
technology have made it possible to automate camera functions in a way never before
possible. Where in the past the typical function of a camera switcher was to sequentially
switch one camera scene at a time on a given monitor, matrix switchers make it possible to
assign particular cameras to any one of a number of monitors.
In addition, focus, pan-and-tilt, and zoom functions can be placed under the control of a
matrix switcher so when someone violates a door or interior motion detector, not only does
the associated camera scene automatically appear on any one of several monitors in any one
of several remote locations, but the appropriate camera can be made to automatically
return to its preset position. At the same time the lens automatically is focused, and--if
included--zoomed to a given degree. Essentially, by the time the camera returns to its
preset position over looking the door or area involved, the matrix controller has in all
likelihood already positioned the lens to the proper focus and zoom.
|
|
|---|