Security Installer

HomeSoftwareArchiveTop TipsGlossaryOther Stuff



One of the more significant contributions digital video signal processing has brought to the surveillance market is low-cost image multiplexing; it's a highly significant technology that until recently was uneconomic for small-scale commercial, industrial or domestic installations. The Dedicated Micros' 4Plex-QK is a good example of how the technology has been cut down to size.


It's a sophisticated, yet easy to use multi-channel video multiplexer that can take the inputs from up to four standard colour or black and white cameras, and process them, so they can be recorded by any VCR as sequenced full-screen images, along with camera idents, time, date and alarm tags. Recordings replayed through the unit can be viewed either full-screen or in quad/split screen displays. Numerous alarm options are available, and most operating parameters can be tailored to suit individual installations, via a comprehensive menu-driven on-screen display.


Externally there's not much to see, it's housed inside a slim, black metal box measuring just 210 x 45 x 335 mm. The front panel is occupied by seven recessed push-buttons, each with its own red LED indicator. An eighth LED, in the bottom right hand corner of the panel, acts as a power-on indicator. The back panel is almost as sparse. From left to right there's an 8-pin mini DIN socket for DC power input, 7 BNC sockets for the various composite video inputs and outputs, and one 9-pin D-connector which handles all of the alarm inputs and outputs. Four of the BNC sockets are assigned to the video inputs, one is for the monitor output, and the two remaining ones handle VCR video input and output.


Power is supplied by a universal switch-mode mains adaptor that operates from a 100-240 Volt AC 50/60Hz supply. Although compliant with several recognised safety standards it nonetheless runs quite hot and installers would be well advised to locate it in a well-ventilated position. Inside the casing there's a single, densely-populated PCB with a high proportion of surface-mounted components. It has been very well built, and apart from component failure there appears to be little that can go wrong. Battery backup for the clock, set-up and mode settings is provided, in the event of a power failure.


Most of the front panel buttons have dual functions. Starting from the left, the first four buttons are the camera input selectors, they also act as set and change keys for the on-screen display, when the unit is in the set-up or time/date adjust mode. Button number five is used to select the replay mode, next to that is the recording mode selector, the final button starts and stops automatic sequencing.


Pressing the quad and record buttons together brings up the main set-up menu. Initially the first page covers language selection (English, French, German, Spanish and Italian), after that comes the main menu with the first option highlighted. This happens to be VCR selection, with over 20 popular time-lapse and surveillance machines included. It also has a VCR patch table, for any models that are not listed. This allows the operator to key in the delay values for the machine they're using. Options are also included for non-time lapse machines


The remaining menu selections include setting the number and type of camera inputs, creating 5-character camera idents, setting the camera dwell time (1-999 seconds), setting the alarm inputs (normally open, normally closed or no input) , selecting the many and various alarm options, resetting the system back to factory defaults and setting up an operating schedule or event timer. For some reason no explanation for this facility was given in the otherwise comprehensive instruction booklet supplied with the unit. That's slightly ironic in view of item on page 1 of the documentation which proclaims ' 4Plex-QK is a product requiring minimum set up and operation skills. Only this manual -- Owners Operating and Installation Guide -- is provided'. The manual also fails to mention a zoom display facility, that electronically enlarges full-screen images recorded in the quad mode.  The instructions do contain useful information regarding a serial port, enabling the multiplexer to communicate with or be controlled by a PC, however, on our sample this socket was blanked off, though clearly there is provision for one to be fitted as an option.



Once the set-up routine has been completed, or no further menu selections are made, the unit reverts to normal operation. The multiplexed VCR output is independent of the monitor and can be safely ignored. During attended operation the user can choose to view any of the four camera inputs by pressing one of the selector buttons, or watch a sequenced display. In the replay mode the operator can choose between a quad display, showing the recorded outputs from all connected cameras simultaneously, full-screen display from one selected camera, or a full-screen sequenced display of all recorded inputs. Each image has the time and date imprinted at the bottom, of the picture, along with the camera ident, and any alarm indications.


The alarm set-up options include the facility to switch the VCR output from a sequenced display to one selected camera; at the same time it will switch a time-lapse VCR into real-time mode. If more than one alarm is triggered all or any of the cameras will be recorded in a new sequence. The monitor output can also be configured to change when an alarm is triggered, to show the output from the relevant camera, or cameras (in sequence).



The 4Plex-QK is virtually transparent to the video signals which pass through it. In full screen display mode there is no significant increase in noise, reduction in definition or noticeable degradation, apart from the inevitable reduced frame rate. This shifts the whole question of picture quality onto the recording VCR. In the most heavily processed quad display mode each of the four images are sharp, colours are accurately rendered and there's plenty of detail.



There's much to commend the 4Plex-QK, it is reasonably straightforward to set-up and very easy to use; performance is good and the price is reasonable. Operationally it leaves only one or two things to be desired. The most obvious omission is a quad display in the recording mode, as it stands the operator can only choose between a single camera or a sequenced display. It would also be useful to preset individual delay times for each camera, though this is a minor consideration, and more than offset by the flexibility of the system as a whole.



Design and design features              ****

Circuitry and components                  ****

Ease of installation and wiring    ****      

Range and variety of functions            ***       

Accompanying instructions                   ***          

Technical advice and backup              

Value for money                         ****                            




( R.Maybury 1995 0601





[Home][Software][Archive][Top Tips][Glossary][Other Stuff]

Copyright (c) 2005 Rick Maybury Ltd.