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MITSUBISHI MELGUARD II SURVEILLANCE SYSTEM

 

Generally speaking multi-camera surveillance systems fall into one of two categories, they're either very basic, or very expensive. Mitsubishi's Melguard II is a concerted attempt to bridge the price and technology gap, bringing advanced multi-camera operation to a much wider market.

 

Melgaurd II has two particular advantages, compared with many other multi-cameras systems. The first and most obvious one for the installer engineer is that the system is modular and the cameras are line fed, which greatly simplifies installation and set-up. Equally important, but this time for the end-user, is that the camera outputs are fully synchronised, so it can optimally sequence up to six pictures per second (25 a second maximum), increasing effective coverage and reducing the chance of vital information being lost.

 

The only significant operational drawbacks with Melguard II is the lack of compatibility with other makes or types of camera, and the current limit of just four cameras, though Mitsubishi acknowledge that they are working on ways of increasing the number of cameras that can be used with the system by developing add-on units. As far as cost is concerned Melguard II compares quite favourably with the competition and a competent 3-camera system could be put together for around 2000..

 

There are four basic elements in the Melguard II system: camera switcher, video monitor, video cameras and time-lapse VCR. The CSM-401 switcher controls up to four compatible line-fed cameras, it has both internal and external sequencing, alarm interfaces, two monitor outputs, camera ident and audible malfunction/tamper warning, this sells for 340. The system monitor is the EM-1408B, it has a 14-inch screen with a 300-line resolution. It has composite and Y/C inputs, loop-through and a remote blanking facility; it costs 336. 

 

Melguard II has three camera options, the MCM331 is a high-resolution (380-lines) monochrome camera with 0.3 lux minimum sensitivity (with f1.4 lens), auto iris, auto exposure and  C/CS lens mount. The CCM411 is the colour version of the 331, it uses a 0.5-inch Hyper HAD CCD with a resolution of 330-lines, a minimum sensitivity of 3-lux, electronic shutter (switchable between 1/50th to 1/10,000 sec),  and auto or manual white balance. The third camera is the CCM412, it has a similar specification to the 411 but with a higher resolution CCD image sensor, giving 460 lines. The three cameras cost 380, 530 and 600 respectively.

 

Mitsubishi offer a choice of  three time-lapse VCRs. The HS-5300E which sells for 1350 has up to 480 hours recording time on a standard E-180 VHS cassette, on-screen menus, automatic head cleaning, fault diagnostic system, audio recording (3 and 12 hour modes only), programmable alarm functions, time/date/camera displays and master clock control for camera switching. The HS-5600 is the Super VHS version of the 5300, it gives improved resolution with the standard cameras but as yet there are no Y/C cameras for use with Melguard II,  it costs 1800. The third  VCR is the HS-5424. This has most of the features of the 5300 but only one time-lapse mode, giving up to 24 hours continuous recording time. The retail price is 680.

 

VIDEO SWITCHER

The CSM-401 is the heart of  the Melguard II system. It does all the hard work, powering up to four cameras, sequentially switching between on-line cameras and synchronising their inputs so there's no disturbance on the video output as it changes from camera to camera. The 401 is uses analogue video processing circuitry, this helps keeps the cost down, and simplifies both the design and construction of the switcher.  Clearly it's not as versatile as some of the latest digital sequencer and multiplexer units and the limited switching options and tape search restrictions could be an irritant in some circumstances -- more about that in a moment -- but this is more than offset by ease of installation and use and cost.

 

The 401 has two video outputs, one carrying the sequenced/triggered output to the VCR and monitor, the other one, called the spot monitor, can be used for an in-store display as it sequences independently of the main video output. Used on its own the 401 has a variable dwell time of between 1 and 60 second per camera but it really comes into its own when connected to one of the three compatible time-lapse VCRs. The 401 takes its clocking signals from the VCR, so, depending on the VCR type and the mode selected, will sequence at a rate that varies between 25 pictures per second (real-time, 3-hour mode), to one every 3.22 seconds (480 hour mode). The 401 is connected to the VCR by a group of five cables carrying the video signal, a camera identity number, VCR clock signal,  alarm hold and alarm input. In addition the 401 has  four external alarm inputs (one for each camera location), two open-collector alarm outputs and a  facility to blank the monitor screen when not in use.

 

 

CAMERAS

The three British-made cameras are based on the same all-metal chassis and casing and follow the usual mounting conventions with two 1/4-inch threaded collars set into the top and bottom of the casing. The 311 mono camera has only two external adjustments, an on/off switch for the AGC, and a mechanical back-focus screw for C or C/S type lenses. The camera has an auto-exposure system and can be used with fixed or auto-iris lenses, which plug into a socket on the back panel. There is one internal adjustment, and that's a switch for setting gamma correction to 0.8 or 0.45 . There are two other sockets on the back  panel, the BNC socket carries video, power and synchronisation signals to and from the switcher, the other one (phono/RCA) is used for checking the video output on site,  when aligning and focusing the camera during installation.

 

The 411 and 412 colour cameras look almost identical to the 311 and have a similar set of sockets for video output and auto-iris but they have additional internal adjustments for setting shutter speed and AGC. A small switch on the back panel selects automatic or manual white balance adjustment. The 411 has a 290,000 pixel CCD,  whilst the 412 is fitted with a 437k pixel chip, which gives a noticeably sharper picture, and less noise, especially at lower lighting levels.

 

MONITOR

The EM-1408 colour monitor is a general purpose type with inputs for composite and Y/C video. It's an uncontroversial design with fairly modest capabilities that are easily exceeded by the cameras, though it is adequately specified  for video playback  within the limits of this  system.

 

VCRS

Finally we come to the time-lapse VCRs. These we have covered in some detail in previous issues of Security Installer but it's worth recapping on the HS-5300 which is likely to be the most popular option for installers and end-users. It's a proven front-loading design with eight time-lapse modes,  from 24 to 480 hours, plus real-time recording speeds which give 3 and 12 hours from a standard E180 VHS cassette. The VCR has a menu-driven on-screen display system for selecting secondary functions, controlling alarm modes and pre-setting the on-board timer which can be programmed to switch the machine on and off up to seven days in advance. Other useful facilities include a self-diagnostic system which displays a fault code should a problem arise, jitter-free replay in still-frame and slomo replay modes,  automatic head cleaning, index marking of alarmed recordings and automatic recording of time, date and camera number.

 

INSTALLATION AND OPERATION

Installation couldn't be much simpler, with only one cable to each camera, and just a handful of leads connecting the switcher, monitor and VCR. Alarm connections, if used are made to a set of screw terminals on the back of the switcher. Setting the system up, once the cameras have been aligned takes just a few moments. With the VCR in circuit the sequence rate is set by the VCR's recording interval, and no further adjustment is required. Without a VCR dwell time is set by a pre-set adjustment on the back of the switcher unit.

 

There are very few operator controls on the switcher unit; a bank of four camera buttons and LED indicators selects individual camera inputs, the 401 automatically skips unused inputs. The remaining three buttons control the monitor-standby function, manual/auto sequencing and the spot monitor facility, a second row of  LEDs, show the spot camera output.  An alarm buzzer sounds if any of the inputs are interrupted. If any of the external alarm inputs are triggered the unit switches automatically to the relevant camera and suspends sequencing for a period that's presettable between 1 and 20 seconds, unless the alarm condition is reset.

 

NIGGLES

The main disadvantage of such relatively simple sequential camera switching system becomes apparent during analytical replay of a recording.  Unlike a digital quad or multiplex system the VCR records each camera output sequentially. Finding a specific time segment or alarm event is simple enough, using the VCR's indexing and time-display facilities, but studying individual images from a single camera, can become tiresome as it's necessary to step through unwanted frames each time. Trying to review a multi-camera time-lapse recording in real-time is nigh on impossible as images flash on the screen at the rate of 25 per second.

 

One other minor quibble concerns the inability to manually interrupt the sequence manually, or isolate one input when it is connected to a time-lapse VCR, without pressing and holding  the appropriate camera button, or installing a second monitor, connected to the spot monitor socket. Mitsubishi say this is a deliberate design feature, intended to prevent accidental interruption of the sequencer but it should be possible to have a time-out facility, so the sequence is halted for a few seconds before automatically resumes scanning. This would be especially useful for, say attended operation where the user wishes to observe or record in real time from a particular camera for more than just a moment of two.

 

PERFORMANCE

For optimum picture quality the 311 and 412 cameras produce the sharpest image, though for low-light situations the 311 has a definite edge and will produce a clear image under normal street lighting. The 411 and 412 cameras are better suited to indoor applications, where light levels are more predictable and remain fairly high. The auto-exposure and white balance systems work well, provided the scene is not subject to rapid or unpredictable changes in light level, produce a sharp, well-defined image.

 

The 5300 VCR is a very able design, picture quality is excellent, as is picture stability in the time-lapse replay modes. It is comparatively easy to set-up and use, though the controls are in an awkward place and some of them can be difficult to get at.

 

OVERALL ASSESSMENT

Although the system is built around a limited number of compatible components they're sufficiently varied to suit most applications. There would appear to be some scope for alternative camera housings and mounting hardware, Mitsubishi do not themselves market weatherproof housings, preferring to leave this up to individual dealers and installers. Mitsubishi have clearly put a lot of thought into Melguard II, and it has paid off because this package fulfils a long felt need by commercial, retail  and industrial users with moderately-sized premises, for an advanced multi-camera and time-lapse system that's realistically priced, simple to install, and capable of good results.

 

PRODUCT ASSESSMENT

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                               ****

 

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(c) R.Maybury 1993 1003

 


 

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