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MV216 Multiplexer






Vision multiplexers have become a key element in multi-camera surveillance systems by making the most efficient use of time-lapse VCRs. Unlike most of the other components in CCTV systems, video recording devices have not experienced anything like the same cost reductions, and so by default have become an expensive resource that requires careful management.


Robot Research have been at the forefront of multiplexer technology and their latest Optima II range embodies many of the most recent developments in digital video signal processing. The MV216 we’re looking at here has 16 camera inputs, (a 9-camera version with a similar spec is also available) and it’s worth reiterating that the cameras can be any suitable PAL/CCIR spec devices, synchronisation is carried out inside the multiplexer and there no need for external genlocking.


The MV216 has five main monitor display modes of 1, 2, 4, 8 and 16 live colour pictures, and a multiplexed VCR output. Additionally there is a moveable 2x zoom mode and picture-in-picture facility. The MV216 features full duplex operation, with multiplex recording continuing in the background whilst the unit is being used to display multiplexed recordings from a second VCR. There are two monitor outputs, one showing a live or recorded multi-camera display, the call monitor output shows a single selected camera input.


The headline features, though, are dynamic time division multiplexing (DTD), and video motion detection (VMD) that work in conjunction with one another to vary camera recording times according to the amount of movement in each picture. In other words, images with no significant movement are recorded less frequently, resulting in a more efficient use of the recording VCR and less wasted tape. The VMD system employs a matrix of 192 switchable ‘targets’ covering the image, these can be switched on or off to define areas of interest, it then compares successive fields from each camera; if a change is detected -- i.e. there is activity in the target area -- the sample rates for that camera, (or cameras) are increased.  The VMD facility can also be used as an alarm function, alerting the operator to movement, displaying the relevant camera and closing an alarm contact.  


Other important features include a menu-driven on-screen graphics with time, date, alarm status, video loss displays plus 10-character camera idents. It has single ‘priority’ camera recording, composite and S-Video VCR input/outputs, and an internally-generated colour bar test card for monitor adjustment. The MV216 has a non-volatile memory, which protects programmed data during a power loss, and an RS232 interface, that can be used for an optional remote front panel, (mounted up to 1000 feet from the unit), alternatively key functions can be controlled by a PC using suitable communications protocols.  



The slim steel case that houses the MV216 measures 432 x 311 x 44mm. The front panel is occupied by a row of buttons, 16 for camera selection and VMD set-up, plus four other groups of display mode, menu select and function keys. The back panel is equally straightforward, with 36 BNC sockets assigned to camera, monitor and VCR inputs and outputs. There are also two S-Video sockets, for S-VHS or Hi8 VCRs, plus two 25-Pin D sockets carrying remote control and alarm interconnections. DC power is supplied by an external AC mains adaptor.


All of the set-up routines are accessed from the on-screen display’s menu selection. Pages one and two are concerned with time and date adjustment and night/day operation, page three covers alarm settings, and page 4 deals with VCR parameters. The next three pages concern VCR timings, camera dwell, title composition and motion detector set-up. The last page contains the security lock options, alarm event and status displays.


At switch-on the MV216 defaults to a 4 x 4 (16) camera display and multiplexed VCR output. The five display select buttons switch between the single and multiple (2, 4, 9 or 16) picture modes; the single image key also toggles the 2x zoom display. The magnified area is shown on an inset sub-screen and defined by a moving cursor, superimposed onto the main picture. The PIP display mode button flips between two selected camera inputs.


The MV16 has four alarm operating systems: it can be triggered by up to 16 mechanical alarms, associated with each camera input; it has a motion alarm that is activated by movement in the camera image; the recorded alarms respond to VIS codes recorded on tape and sensed during playback, and a video loss alarm that is engaged if any camera input is lost. The response varies according to the type of alarm input, but it can involve flashing the relevant camera indicator light, energising the unit’s alarm relay, sounding a buzzer, displaying a relevant alarm message on the monitor screen, and where necessary switching to the alarm encoding rate or camera priority mode on the VCR output.


Routine operations are unambiguous and simple to understand, though the instructions are fairly dense in places, and some operations could be more clearly explained with the use of diagrams, nevertheless all the necessary information is included.



The quality of image output from the MV216 is most impressive, despite the indications of the extensive digital processing involved. This results in a small reduction in detail and dynamic range, compared with a raw analogue camera output. Noise levels are low and colour fidelity is very good. In the multiple image display modes there is a further reduction in resolution, though this does not affect the multiplexed VCR output. Playback picture quality is entirely dependant on the performance of the recording VCR.  S-VHS equipment will resolve slightly more detail, and noise levels are generally lower.



The quality of construction, design and performance are all remarkably good, moreover installation and operation are difficult to fault. The DTD and VMD facilities give this device a significant functional advantage over similarly-specified multiplexers, and must qualify as critical features that should be taken into consideration when specifying a multi-camera system. Robot are the acknowledged leaders in the field of video multiplexing and it clearly shows on the MV216 which exhibits a high level of refinement and sophistication.





Design and design features             *****

Circuitry and components            *****

Ease of installation                     *****

Range of functions                       ****

Accompanying instructions            ***

Technical backup              ****

Value for money            



Ó R. Maybury 1995 2610



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