Security Installer

HomeSoftwareArchiveTop TipsGlossaryOther Stuff



The Hitachi VK-C220 colour video camera is a convincing demonstration of the growing importance of digital electronics, and the impact that it now having in all areas of video processing. This camera depends almost entirely on digital technology, from the CCD imaging chip and signal processing circuitry, through to a specially designed RS232C PC interface, which can be used by service engineers to access and adjust some of the cameras critical functions, without taking the lid off.


This feature has migrated from domestic video equipment, in particular camcorders, where, because of space limitations and the need for a high level of reliability, methods have been devised to reduce both the number of components and internal adjustments. To this end many machines now have software set-up routines, with a growing number of key camera adjustments stored as digital data on EPROMs (erasable programmable read-only memories). Faulty or mis-aligned camcorders with this facility can be connected to a computer running suitable diagnostic software, either locally at a service agent, or remotely --  via a modem -- to a computer at the manufactureís main service centre. It is then a simple matter to use the computer to identify errors and if necessary download corrected data.


The VK-C220 doesnít go quite that far, but itís clearly a taste of things to come. Weíll look at the PC interface in more detail in a moment, but first a run through the general specification. 


Itís a sub-compact design, the metal case is only 50 x 50 x 125mm, and it weighs in at just 370 grams (both measurements exclude the lens). It is fitted with a C/CS lens mount, a simple screw-clamp adjustment changes the mount from one type to the other. Behind the lens thereís a 1/3-inch CCD image sensor with around 437,000 active pixels, thatís sufficient to give a horizontal resolution of 460-lines; low light sensitivity is rated at 3 lux (f1.4 lens). 


The other headline features include a simple to use menu-driven on-screen display (OSD) that givers the installer and end-user ready access to a variety of additional functions, without having to fumble with internal switches or buttons. They are: automatic or manual white balance, variable shutter speed, from 1/50th to 1/10,000 th second, an 8-character camera ident, backlight compensation, switchable AGC and ALC, neg/positive switching and an electronic zoom with a magnification factor of 2x.


Within some of the selections there are additional options. The camera ident is chosen from a full alphanumeric character set and the finished title or ident can be superimposed on any one of six locations along the top or bottom edges of the picture. The electronic shutter has seven pre-set speeds (1/50, 1/100, 1/250, 1/500, 1/1000, 1/2000 and 1/10,000th sec), plus auto-exposure, where shutter speed is set automatically, according to the incident light level. The automatic white balance function can cope with most situations, though if the scene is lit by a mixture of differing light sources manual intervention may be required. The OSD adjustment includes an option to set white balance using a white reference card, or each colour can be individually emphasised or demphasised as needed.  The backlight control divides the image into six areas,  which can be individually adjusted to correct for strong backlighting. The areas to be masked are clearly shown by the on-screen display.


All of the OSD functions are controlled form a set of just three buttons, in fact they are the only exterior controls, apart from the focus and manual iris adjustment (where applicable). On the back panel there are four sockets, two BNC connectors (one for composite video out, the other for external sync input),  and two mini DINs, for DC power and an auto-iris lens. Data for the RS232 camera-to-PC interface and external switching (wide or tele) for the zoom facility are routed via the power socket. There are standard threaded mounting bosses on the top and bottom panels.


Internally there are five main PCB, all built using surface-mounting component (SMC) technology, for improved reliability and ruggedness, the boards are held in place by an all-metal chassis, it looks and feels as though itís built to last.


The PC interface or DAP (digital adjustment program) is essentially a servicing procedure, rather than a user or installer facility but itís worth outlining how it works. The interconnection requires a small box that fits between the camera and the computer; incidentally this has to be an IBM or compatible machine, capable of running  DOS software. The box has three connectors, one for the DC power supply, the second one carries power and data to the camera, the other is a standard RS232 serial interface that hooks up to one of the PCís COM ports.  Once all of the connections have been made, and everything switched on the program can be run by typing in a few simple commands. This brings up a menu with two selections, for setting white balance and chroma gain. The WB option gives access to red and blue colour gain, which can be accurately set using  an oscilloscope or vectorscope. The adjustments are made from the computer keyboard using a set of four defined keys. Once set the data is written to the cameraís EPROM. The Chroma gain adjustment follows a similar routine.



The C220 meets all of Hitachiís outline specs with ease. Using a supplied Computar lens (12.5mm, f1.4) it produced a clean, well defined image. In good natural light the autoexposure and white balance systems can cope with a broad range of operating conditions but thereís sufficient flexibility within the manual exposure options to ensure it can deal with tricky situations. Noise levels are very low and although the low-light performance isnít going to break any records it still provides a useable image, even in poorly lit scenes. The electronic zoom facility is a mixed blessing, on the one hand it provides a quick and simple means of magnifying the image; unfortunately at full power there is a drastic reduction in resolution with the picture taking on a blocky appearance, with slight instability on fine, bright detail.



In general performance terms the C220 is a competent though unremarkable colour camera, however the range of advanced exposure options, coupled with the small size and rugged construction combine to make this an unusually versatile design, suitable for a wide variety  of demanding applications. The efficient and easy to use on-screen display, and the PC interface are key features that will make the lives of installers and service engineers that little bit easier right now, and hopefully, increasingly so in the future.




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 3003











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

Copyright (c) 2005 Rick Maybury Ltd.