Security Installer

HomeSoftwareArchiveTop TipsGlossaryOther Stuff






The proliferation of dome cameras, particularly in retail and commercial installations, speaks volumes for the effectiveness of this type of surveillance device but for the end-user and specifier it represents a tricky balancing act. The decision to use a dome instead of fixed cameras involves trading the significant extra cost and potential for additional maintenance against the increased flexibility and coverage. In short they’re expensive and there’s more to go wrong but that’s something JVC is keen to address with the TK-C676 dome, which has been designed for demanding applications that require continuous 24-hour operation, in manned or programmable operating mode.


The feature list is a long one and headed by the camera specs, which include very low light operation, down to 0.5 lux (colour, with gain up enabled) and 0.0125 lux (black and white, gain up). The 1/4-inch Interline Transfer CCD has a 752 x 582 pixel array giving a claimed resolution of 480-lines. Up front the integral lens has a 27x optical and 2x electronic zoom (F1.4 – F3.0, 3.8 – 103mm), focus is automatic or manual and there’s an IR switching function so it can operate in infrared lighting.


Extensive use is made of digital signal processing, the advanced auto exposure system has an additional facility that JVC calls ‘Extended Dynamic Range’ and together they are able to operate in a very wide range of conditions, including scenes containing bright lights and strong backlighting. 


The camera can pan continuously through 360 degrees at a speed of 1 to 300 degrees/sec; the tilt range is 0 to 180 degrees at a speed of 1 to 180 deg/sec, with automatic flip as the camera passes through the horizontal.


When used in conjunction with its companion controller (JVC RM-2580, which can control up to 32 cameras), facilities include auto patrol mode, auto trace and pan with automatic area titles (16 areas each designated by a 16-character ident). The controller can store up to 100 pre-set positions and there are privacy mask and motion detection facilities, the latter with optional alarm activation. The unit also has four alarm inputs, when triggered the camera automatically moves to the Home position or any of the 100 presets. Three alarm outputs are provided, one of them operating a mechanical relay built into the dome.


The controller also gives access to the camera and dome’s many configuration settings which are adjusted from a set of menu-driven on-screen displays. Telemetry and communications between the dome and the controller can be via either RS-232 or RS-485 twisted pairs and it requires a 24-volt AC power supply.


It certainly looks as though it’s built to last but there’s not a lot to see from the outside, the design is simple and unobtrusive, it’s well protected too with no visible external fittings or attachments that might be of interest to vandals. All of the components inside the clear dome are coloured black so as not to draw attention to camera movement or position. The housing is water resistant (to IP52 standard), which makes it suitable for use indoor installations or locations where it won’t be subjected to direct water splashes.


To get at the ‘works’ the outer cover, dome and black camera shroud have to be removed. It is clearly a very well built piece of precision engineering. The motorised platform is housed inside a tough alloy cylinder. At its heart is a metal chassis that provides support for the power supply and drive electronics circuit boards and the pan-motion stepper motor. This drives the rotating platform on which the camera is mounted using a toothed belt and pulley reduction drive. The actual camera module is encased inside a black almost donut-shaped module, mounted on a pair of bearings and moved by a second stepper motor via double belt-driven drive chain. The turntable is also home to a densely populated PCB that includes the video processing and telemetry circuitry.


Connections to the outside world are made using a quick-release (bayonet fit) mounting plate on the top of the dome, our sample proved to be a little stiff but nothing a dab of grease wouldn’t cure. The plate has a single multi-way connector, fitted to a sliding plate, that mates with a female connector in the top of the dome. It’s a simple and secure arrangement that makes it possible to remove or exchange camera units in just a few seconds. A range of mounting options is available including ceiling hanger or wall mounting hardware and direct or embedded ceiling brackets.



The dome is more or less ready to go straight out of the box. In a multi-camera setup the only adjustment is to set the camera ID using a pair of rotary switches located on the top of the dome. The rest of the setup is carried out remotely from the controller. To call up the on-screen display the menu button has to be pressed for 3 seconds, this brings up three options: Position Setup, Camera and Control Unit. Selecting the Camera menu displays a sub-menu with a further eight options: Camera Function, Title/Alarms, Video Adjust, ALC/ExDR, Motion Detection, Pan/Patrol/Trace, Position Function Set and Factory Settings.


Camera Functions cover vertical phase, title position, flip (auto or digital – the picture is inverted or the camera pans through 180 degrees), PT speed – variable or fixed, auto focus, digital zoom and privacy mask. The Title/Alarms menus are used to compose on-screen idents and titles and configure the alarm inputs and outputs. The Video Adjustment menu deals with colour level, picture enhance, pedestal and auto backlight control. ALC/ExDr is for exposure settings including Average:Peak values, shutter speed (manual 1/50th to 1/10,00th sec in 8 steps) AGC mode (off, 10dB, 20dB ‘Super), Sense up (essentially a ‘slow’ shutter), Priority (between picture quality or capturing motion), ExDR (Extended Dynamic Range mode which helps to capture scenes or objects with large differences in brightness level) and BW/Colour mode.


Motion Detection is activated when the camera is in the Home position, the menu has settings for sensitivity level, area edit (the screen area is divided into a 8x 6 grid of individually selectable ‘targets’). This sub menu also has settings for the alarm display, when motion detection is triggered. The Pan/Patrol/Trace menu deals with the setup for the autopan mode (right, left, return) and auto pan speed (low, normal. High), plus the start and return positions. There’s also configuration settings for Auto Patrol and Auto Trace, the latter stores 30 seconds worth of manual camera actions. The Position Function Set menu sets the preset titles (up to 99 positions are stored); in addition there are settings for iris mode (auto, semi auto, manual), backlight compensation, white balance (auto or auto tracking), and R-B Gain and M-G Gain adjustments.


Despite the long list of options setup is relatively straightforward and unless conditions dictate otherwise the camera can be quickly up and running on the defaults, leaving the installer to fine-tune the settings when the rest of the adjustments and programming has been completed. For the record the instructions are clear and concise with plenty of illustrations.



We’ll deal with the PTZ mechanism first. It is excellent, fast, smooth and very responsive though it pays to have a steady hand as the joystick can be very sensitive. Movement can be controlled very precisely, there’s no backlash or overrun and it’s a genuine delight to use. On the bench the motors are quite noisy but only when moving at top speed, however, it’s unlikely to be a problem in normal operation, once the unit is installed a lot of the noise will be dampened


The camera also performs exceptionally well delivering a crisp and sharp image in a wide range of lighting conditions. Colours are faithfully rendered in natural light and it’s safe to leave colour balance in the hands of the camera’s auto systems in daylight and most mixed-lighting situations. Resolution on our sample was more or less as advertised, certainly in excess of 450-lines under test conditions. Low light sensitivity is most impressive. As light levels fall there is a gradual increase in picture noise levels and colours tend to go a bit muddy, eventually disappearing altogether but provided there’s not too much movement the combination of slow shutter and gain-up produces a viewable image down to very low light levels.



Aside from some very minor niggles concerning control sensitivity and the legibility of some of the on-screen displays the TK-C676 scores very highly in terms of performance, ease of installation, setup and use. It’s a sophisticated design, very well built and on the evidence so far there’s every reason to suppose it will have a long and useful life. There are plenty of compact dome camera on the market at the moment, some of them very good indeed but try and see this one in action first as it will give you a benchmark to judge the others by.



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                         ??                          



ă R. Maybury 2002 0404



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

Copyright (c) 2005 Rick Maybury Ltd.