The Matrix Revealed
Long before Keanu Reeves’ blockbuster movie helped make it a pop cultural phenomenon, folks in our industry were well acquainted with “The Matrix.”
Once the mainstay of video surveillance and still one of the most sophisticated products widely in use, the cross-point matrix switching system, or matrix switch, has come a long way. On one hand, it is still the predominant method for routing video signals around a facility. On the other, there are many products that have taken large portions of its functionality.
Determining which particular applications matrixes best serve necessitates a thorough understanding of the devices’ capabilities and how they accomplish these functions. Don’t worry: It’s much easier than trying to make sense of the convoluted storyline in that other “Matrix.”
Matrixes Do Much More Than Just Direct Video Signals
At its essence, a matrix switch is a device that routes signals in response to commands. This doesn’t just pertain to video signals; there’s a lot more going on in the matrix as explained below:
Video Signals – A connection is made from an input (often called camera, but it can be any type of video signal) to an output (typically a monitor, but often a VCR or DVR). An internal distribution amplifier is provided to allow the input to be connected to any number of outputs without any signal degradation.
Titling Information – Information about the various input signals can be programmed into the system and superimposed over the output signal along with a real-time clock. This allows camera titling and alarm information to be presented to the operator along with the video image.
Telemetry and Control – When an operator selects a camera on their controller and assigns it to a monitor, a connection is also made between the controller and the camera. If the camera is one that accepts a data connection, the operator can send pan, tilt, zoom and, in many cases, fairly sophisticated programming and calibration instructions.
- External Commands – Commands are sent from other devices to the matrix switch. Depending on the sophistication of the switch, these commands can call cameras to monitors, initiate contact closures (to lower a gate arm or lock a door, for example) or perform a macro (series of commands). Other devices that send commands include alarm panels, access control systems and other computer-based systems (see sidebar in May issue of Security Sales & Integration).
To perform these tasks, a matrix switch is functionally divided into three sections: The CPU is the brains behind the operation, accepting input and sending out commands to the other components. The switcher routes the video signals from inputs to outputs and the titler superimposes time, date and title information over the monitor outputs.
Smaller systems contain all of these components in a single box, while more sophisticated systems that can be scaled to 4,000 or more inputs have separate boxes, or card cages, for different functions. In fact, some larger systems even utilize multiple CPUs to keep one function from overwhelming the system and degrading performance.
3 Data Streams Dictate Communication Parameters
A matrix is basically a closed system that communicates between its internal components through a proprietary protocol. That’s OK, since we don’t have a need to communicate directly with the subsystems that make up the matrix. We’re interested in controlling the matrix and having the matrix control devices like domes and pan/tilt motors.
To do this, we have three data streams that concern us:
Telemetry – The data stream a matrix uses to talk to domes or other pan/tilt devices is called telemetry data. At one time, all the devices that would communicate with a matrix used motors connected to the matrix through a receiver-driver unit, or RDU.
The matrix and the RDU communicated using a proprietary protocol, and the RDU interfaced to pan/tilt motors and lenses through a series of relays and transformers. While these are still used for some specialty applications, the remotely positioned camera of overwhelming choice today is the dome camera, which includes its own RDU.
Not too long ago, the proprietary nature of this telemetry data stream was a major competitive advantage to the matrix switch manufacturer. Since the matrix switch you purchased dictated the type of dome you had to buy, and vice versa, the two were intertwined.
Some industry estimates have shown that every dollar of switch revenue led to $10 or more of accessory device sales (e.g. domes), making matrix switches an enabling product that was far more important to manufacturers’ bottom lines than their sales numbers would lead you to believe.
Today, things are different. While the matrix still sends out a proprietary data stream (there are a few exceptions), most dome manufacturers have reverse engineered their competitors’ data streams and added them to their domes, either in firmware or by using plug-in modules.
System controllers – It has been said that the system controller (sometimes called the keyboard) is the true differentiator of a matrix switch. As a mature product, most matrix switches are as full-featured as the average user needs. However, except for specialized applications, the end user sees them as invisible boxes that magically route their video signals.
It’s the controller and monitor that operators spend all of their time with. That’s why the devices’ display, joystick and colorful buttons receive the bulk of a customer’s attention when selecting a system.
But there must be more to the controller than just bells and whistles. Since the matrix is the heart of the system, the controller must be functional as well as aesthetically pleasing. Consider getting sample controllers in front of the end user and letting them decide.Evaluate the display: Is it too graphical, hard to understand, intuitive, or would the customer lean toward simpler or more complex? Buttons are an area of strong preference as well. Some are rubberized keys with little tactile feedback, while others are “clicky” computer keyboard-style buttons that may be less attractive but more durable and functional. The layout is also important, and must work for lefties as well as right-handed people, and the whole controller must be substantial enough that it doesn’t slide across the desk while in use.
Some systems also offer the use of a graphical user interface (GUI). This is a computer acting as a controller that manipulates the system through a series of on-screen icons or keyboard shortcuts. These often include map-based displays that allow the user to click on icons on a graphical representation of their facility.
External control – To integrate a matrix switch with other products, such as access control systems, alarm panels, fire systems and building controls, a high-level interface is required. This usually consists of one or more data ports that accept a stream of data from another system and respond appropriately. (For more, see sidebar in May issue of Security Sales & Integration.)
Alarm inputs are another form of external control and have many uses. These can be connected to contacts on the switch itself (on smaller systems), through an external alarm-gathering panel that converts contact closures to a data stream that is fed to the switch or through contacts in the domes that feed alarm data to the switch as return data (on bidirectional systems).
Alarms are great for widely disbursed discreet activities, such as panic buttons, motion detectors, door contacts, doorbells and other sensors. In fact, alarm inputs are often used to perform less sophisticated (but often more reliable) system integration by allowing a direct connection to the alarm output of another system (such as a fire panel a
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