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Its two steps forward and one step back with this colour multiplexer from Sanyo that manages to combine advanced digital processing technology with simplicity, flexibility and ease of use



It is fair to say that in the space of less than five years digital video multiplexing has transformed large areas of the surveillance industry, turning what used to be prohibitively costly and complex technology into an affordable option for many small and medium sized businesses. In addition to some quite dramatic price reductions the specification and performance of multiplexers has steadily improved, to the point where some 'basic' models are now comparable with top-end units of just a couple of years ago. Features like full duplex operation have become almost commonplace and it has reached the point where there's relatively little difference in the cost of 8 and 16 channel units, bringing multi-camera coverage within reach of a much wider market.   


The Sanyo MPX-CD16P 16-channel colour multiplexer and its stablemate, the MPX-MD16P (black and white version) clearly illustrates the point. In addition to duplex operation, which allows simultaneous recording and playback it also has a multi-screen display, electronic zoom, live display during playback, 16-channel alarm function, camera titles, still image and an alarm log, to name just a few.  


Sanyo has stuck to a tried and tested format as far as the general design and layout are concerned. The unit is housed in a slim, free-standing or rack mountable case measuring 420 x 44 x 320mm. On the rear panel are 32 BNC connectors for the video inputs and associated loop-throughs, additionally there are a pair of BNC sockets the monitor outputs and two more for the VCR input and outputs. A set of S-Video (Y/C) mini-DIN sockets is also provided for connection to an S-VHS time-lapse VCR, for even higher recording quality. Alarm sensor inputs and connections for an external hard-wired remote control are routed through a 25-pin female D-Sub. VCR switching/comms is handled by a 2-way spring-terminal. The multiplexer is powered directly from the mains; the supply cable plugs into a standard two-pin Telefunken socket on the far right of the back panel.


The case is made from extruded alloy sections with steel top and bottom panels; it looks and feels very robust. Inside the box there is one large PCB containing all of the video processing circuitry, three smaller boards on the back are for all of the input and output sockets, there's also a power supply board and a low-profile mains transformer. The mainboard is mostly populated by surface mount components. Approximately one third of the board is shrouded by an earthed metal screen, which we suspect is a consequence of the internal power supply. The standard of construction is very high and our usual repertoire of intermittancy tests (a few healthy taps...) showed the board and connections to be very stable indeed. Accessibility is good, not that there are any installer or operator adjustments inside, but it bodes well for long-term reliability and servicing


The front panel is a model of simplicity. From left to right there is the on/standby button, followed by 16 camera select buttons and their associated LED indicators. A small hole, slightly off-centre, contains a recessed clock reset button. On the right side there's a row of 8 buttons, 7 with LED indicators. Between them they handle display switching, still frame mode, zoom function, sequence on/off, multi-screen display, live display, VCR playback and the on-screen menu. Set-up options are selected and set using the four keys to the right of the menu button.


Pressing the Menu button mutes the image and brings up the first page, which contains seven numbered selections. From top to bottom they are: Clock Set, Title Set, Alarm Set, Display Set, VCR Set, Alarm Data and Enter. The clock and calendar are Year 2000 compliant, it passed our standard Y2K rollover check without a hitch and correctly indicated that 2000 is a leap year. The camera ident can contain up to 8 alphanumeric characters and may be set to one of seven vertical positions. On the Alarm Set menu there are options to enable or disable an internal buzzer and set the duration plus switch re-trigger on or off (to accept or ignore a second alarm input during an alarm event). It also has switches for an alarm-triggered zoom and freeze on monitor 1, switch alarm display to monitor 2 and enable or disable a video loss alarm.


The Display Set menu contains switches for the clock and title display on live and VCR playback, monitor 1 and 2 sequence times (0.5 to 30 seconds in 0.5 second increments) and switch monitor 1 output to monitor 2. On the VCR Set-up menu there are adjustments for VCR mode (SP & LP), VCR recording speed or time-lapse mode and alarm event recording speed (on VCRs with remote switching facilities). The Alarm Data display logs the camera number, date and time of the previous 100 alarm events.


Alarm responses are fairly basic; when triggered a warning bleeper sounds for a pre-set period, a flashing letter 'A' appears on the screen, and the display changes to multi-screen mode, additionally it can be set up to zoom or freeze the image on the associated camera. The alarm inputs remain active, even when the unit is in standby mode and it will automatically switch on and display a multi-screen image if an alarm occurs whilst it is switched off. Alarm events are flagged on a recording and the flashing 'A' appears during playback. The event is logged but after the initial audible alarm no other on-screen or front panel indications remain to show that an alarm has been triggered.



Menu navigation is reasonably straightforward, though the labelling for the secondary functions (light blue on brushed aluminium) can be awkward to see in subdued light. Most routine functions are simple to follow but one or two are quite convoluted. The zoom option is a good example; pressing the zoom button enlarges a portion of the screen, to change the selection -- effectively an electronic pan and tilt -- it is necessary to hold the relevant camera selector button for 3 seconds, after which the word 'set' appears on the screen. The zoomed area can then be adjusted by using the 'Live' and 'VCR' buttons to shift the display downwards and sideways. The image only moves in one direction, so if you overshoot it is necessary to keep stabbing the button (or hold it down) until the image scrolls around again. To get back to a normal image it is necessary to press the camera and zoom buttons again.


Pressing the 'Multi' button cycles through the display combinations, which includes eight permutations of 1/16th and 1/4-sized sub-screens (4 x 4, 2 x 2, 8 + 2 & 4 + 3). Unfortunately the display assignments cannot be changed; the only way to configure a particular layout -- so that images appear in the order and position you require on the screen -- is to physically swap the camera inputs. Zoom and freeze-frame displays can be selected from any input and there's a facility to insert a 'live' 1/16th or 1/4 screen display from a nominated camera whilst in the multi screen mode.


During VCR replay the same multi-screen options are available, including of course a normal full screen display form any recorded camera input. Whilst full duplex operation is possible, it's worth pointing out that this entails the use of two VCRs (one to continue recording, the other for playback). However, since the unit only has only one set of VCR connections (S-Video connections can't be used at the same time as the composite inputs), it will be necessary to disconnect the video output from the recording VCR and replace it with the video output from the second replay machine. This could be inconvenient if, for example, the multiplexer was installed a rack, with limited or restricted access to the back panel.


One final operational quibble. Putting the clock reset in such a prominent position in the middle of the front panel is asking for trouble. True, the button is recessed but it is unmarked and begging to be prodded with the tip of a ball-point button. It would have been better to put it on the side or assign the function to a button combination -- like master reset (hold Menu and press On)  -- that is unlikely to be invoked accidentally.


One final oddity, the unit appears to have an unadvertised facility in the shape of a test pattern generator, useful for testing or setting up a monitor. We discovered that if the Sequence button is held and then the live button is pressed a set of colour bars appears. We couldn't find any mention of it in the instructions or on the spec sheet, though that's not to say it isn't tucked away somewhere in the small print as the presentation can be a bit haphazard in places.  



Live full-screen images are as clean as a whistle. The bandwidth is in excess of 430 lines and on the majority of general-purpose cameras there will be little or no loss of detail or any increase in noise levels. Colour fidelity is generally good with no obvious aberrations or change in registration. Camera switching a full screen display is supposed to occur during one field period. The switchover is clean but the camera ident and date/time display disappear for about half a second, which is slightly disconcerting especially when seen out of the corner of the eye.


Apart from the inevitable reduction in frame rate and detail that occurs on a multiplexed, multi-screen image, the overall picture remains sharp in all display modes. Playback of multiplexed recordings is crisp and there's no breakthrough from other channels on full-screen replay. The instructions warn that 12 and 24-hour time-lapse recordings with audio may cause interference, that wasn't a problem on our test set up but the split screen images made at those speeds were slightly unstable with a small but noticeable vertical judder. 



Although fairly basic by current state-of-the-art multiplexer standards the MPX-CD16P stacks up well as a competent workhorse. It provides a quick and easy means of upgrading older equipment or increasing the capacity of smaller systems, or it can function as the core component in a complete multi-camera set-up. Either way it is a highly adaptable no-compromise design, and what it lacks in fancy features it more than makes up for with good on-screen performance and build quality. 




Power supply              230 VAC 50Hz

Weight                        5.7kg

Dimensions                 420 x 44 x 320mm





Product design 8

Build quality               9

Ruggedness                9



General functions            7

CCTV functions            8         

Ease of use                 8

Instructions                7

Manuf. support            ?                     



Video quality              9

Switching                    8

Audio                          n/a



R. Maybury 1998 1214



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