Knowledge Base

A » Back Light Compensation (BLC) digitally compensates for high-lights to enable silhouetted scenes to give more detail.

When a camera is positioned looking at the entrance of a large glass fronted shop for example, the person walking in will often be silhouetted especially when the external light is high, as on a normal sunny day.

The bright light will force the automatic iris to close.  The camera can compensate to some degree for the difference between the ambient lighting and the light falling upon the target to be observed. However wherever possible use the ambient lighting to assist the camera technology.
 

A » Lux is a measurement of light. To gauge the sensitivity of a camera we try to quote what level of light is needed to produce a video signal which is more than just a faint shadow and a screen full of snow.

Therefore the lower the lux rating, the higher the sensitivity and the better the image will be in low light levels.

Here are some typical estimates of lux levels:-

• Bright sunny day: 10,000-100,000 Lux
• Overcast day: 1,000-10,000 Lux
• Twilight: 1-100 Lux
• Street Lighting: 5 Lux
• Full moon: 0.1 Lux
• Bright clear starlight: 0.01-0.0001 Lux

However, these indications are generally measured at the scene; i.e. someone stood under a street light with a lux meter and measured 5 lux. Unfortunately our CCTV camera is not under the street light – it is some way away looking at what is under the street light and therefore looking at reflected light.

Imagine how much light is bounced back from the person under the street light in a dark jumper and jeans, probably only 5-10% which now means our 5 lux is reduced to a paltry 0.25 lux which may well produce an image on a camera with a sensitivity of 0.1 lux but we are very close to its working limit and this will show in the quality, clarity and detail of that picture.

A »
LILIN manufacture an extensive range of CCTV Cameras. The range incorporates many different features, specifications and designs, we have a product for every application. The different types of cameras available include:-

CCD
The majority of our cameras utilise Charge Coupled Devices, silicon chips that are sensitive to light, that measure about 1/3” diagonally. The growth in the camcorder market has led to a dramatic improvement in the sensitivity and resolution of these chips and has also reduced the overall cost of modern cameras.

DSP
Digital Signal Processing improves many aspects of the picture quality including; edge enhancement and Back Light Compensation. The DSP chip-set replaces a number of analogue IC’s and utilises built in intelligence to maintain optimum picture performance without the need for external adjustment.

Resolution
One of the ways a camera is judged is on its ability to resolve detail. This is measured in TVL, or Television Lines by using a special test chart which has a series of patterns, that relate to certain resolutions. The camera should be able to define all the patterns up to its specification, the patterns with a higher number of TVL than the camera can resolve will appear blurred. Many components in a CCTV system use TVL to define their performance, the lowest resolution component will be the limiting factor in the performance of the entire system.

Sensitivity
This rate a cameras ability to see in the dark, it is measured in lux, which is a measurement of light. So when we say a camera has a sensitivity of 0.1 lux it should provide a useable video signal in those lighting conditions. As the low-light performance is also affected by the lens used we should quote an F-stop to show how the figures were achieved.

Electronic Shutter
This is a function that allows a camera fitted with a manual iris lens to automatically adjust the video level under varying light conditions. Without this function the camera would white-out or need to be used with an auto iris lens. It effectively reduces the cost of installing cameras in many applications where an auto iris lens would have been used, however we still recommend auto iris lenses for most external installations.

A » Reliable video signal continuity through a CCTV system is paramount to picture performance and durability. Making good connections is just as critical as choosing the right products and has a significant effect on the long term operation of a CCTV system.

On it's travels from the camera to the monitor the analogue video signal has to pass through a number of seperate pieces of equipment such as switchers, VCR's multiplexers and so on.

Each Piece of equipment requires a video input, and usually a video output or loop through, to pass the signal onto the next piece of equipment. At each of these points it is usually necessary to terminate the coax cable with a male BNC in order to make the connection.

Often there may be as many as 6 or 8 BNC connectors between the camera and the monitor, if the BNC connectors are made poorly the chances of a clean video signal drop proportionately.

These are some of the faults commonly found with BNC connections;

Shield Short, where strand of copper braiding is touching the certer core. Usually as a result of incorrect stripping.

Short Core, where the core fails to make solid connection with the pin, or the pin is not proud enough within the connector.

Weak Crimp, often as a result of the wrong tool (such as pliers) or a worn crimping tool being used on the pin or ferule. The connection may seem OK to look at but cold weaken through strain.

The different types of BNC connectors on the market have their own advantages and disadvantages but the same fundamentals always apply;

• Always use the correct tools for stripping and crimping
• Always use the correct 75 ohm BNC on the correct grade of 75 ohm coax cable
• Follow the connector manufacturer's instructions and strip the coax to the specified lengths
• Use strain relief boots to for added strength and security

A » Historically infrared lighting was used in high security CCTV installations, where surveillance tended to be more covert. It offered the advantage of effectively allowing the operators to "see in the dark", illuminating the area for the camera but not the naked human eye.

Today these applications account for a small percentage of CCTV installations but the use of IR lighting still has a number of advantages. The most common application for IR lighting is to provide good illumination for the camera system without causing the environmental light pollution that would normally be created by visible lamps such as Tungsten or High Pressure Sodium. Additionally there are sometimes benefits in keeping protected premises in the dark, so that the opportunist is not given assistance in assessing and gaining entry to toe premises.

IR works because the human eye is only sensitive to light in the range of 400-700nm, whereas a monochrome CCD camera is sensitive beyond 700nm and well into the infrared spectrum. So the infrared lamp generates a light source that we can't see but the camera can, providing invisible or "Black Light".

Actually many sources of light also produce infrared, including the sun and filament light bulbs. With color cameras we actually need to filter out these wavelengths so we can reproduce colors on the monitor in the same way we see them naturally, this means most color cameras won't work with IR.

To produce IR we actually jsut filter off the visible light from a halogen type filament bulb, so that only the IR content is passed. Effectively this means we are only using part of the potential output of the bulb, if we were to remove the filter from the lamp, the camera would actually perform better as it can now utilise the full spectrum of light produced.

IR lighting is not the only type of lighting that can be used with CCTV systems, Tungsten, High Pressure Sodium and Mercury lamps all provide suitable outputs for CCD cameras, however the advantages of the discreet light source will still make IR a popular choice for many applications.

A » Looking at the use of infrared illumination in CCTV over the years you could be forgiven for predicting it’s obsolescence sometime around now; short bulb life meant expensive running costs, as CCD camera technology continued to improve sensitivity levels increased, integration techniques and day night switching all add up to reducing the requirement for IR lighting.

But then the humble Light Emitting Diode (LED) proved it could also provide infra red light, being continuously improved to the extent that is has now become a very cost effective source of IR. The modern LED has a life expectancy of 20,000 hours and is designed to emit a range of beam angles in the near infra red (750 – 1000nm), making them perfect for IR sensitive cameras, including modern day/night switching cameras.

The secret to achieving high reliability and good power outputs is in the quality of the diodes, the way they are driven and the ability of the lamp assembly to dissipate any generated heat. Running the LED at less than 100% of its maximum power input will increase longevity with only a small drop in output.

Using Aluminium PCB’s allows superb heat dissipation and a well planned circuit layout will help prevent hot spots and even beam spread.

The rapid growth in number plate recognition systems has also driven a resurgence in requirements for LED illumination, using IR light to highlight car number plates at night without dazzling drivers. LEDs operate year-after-year making them ideal for applications that require a reliable light source and they use only 10% - 20% of the energy consumed by an equivalent conventionally-constructed IR lamp, when combined with their maintenance free operation substantial cost savings can be realised.

Some of the new products adapting this technology provide single unit solutions, with camera, LED illuminator, lens and weatherproof housing in a compact and easily installed device. With colour cameras the IR filter can be automatically removed, once light levels drop – often known as Day/Night cameras, or special low pass optical filters can be used that pass IR without disrupting the normal colour balance. In either case the device can be designed to optimally combine CCD, filter, lens and DSP circuitry to make best use of the infra red source and still provide excellent colour images during normal daylight.

More powerful LEDs are also being incorporated into full size external housings, capable of taking a wide range of camera/lens combinations and providing up to 80m ranges. This allows even more flexibility but still offers a single unit solution, neater installation and lower running costs.

When looking at the new products reaching the UK market, remember that the performance of these devices varies substantially based on design and quality, just with any CCTV component, evaluate the performance in various situations and try to compare devices side by side where possible.

A » Degrees of Protection

First Digit
The first digit of the IP code indicates the degree that the equipment is protected against contact with solid foreign bodies intruding into an enclosure, e.g. dust

Second Digit
The second digit indicates the degree of protection of the equipment inside the enclosure against the harmful entry of various forms of moisture (e.g. dripping, spraying, submersion, etc.) 
 

A » A variety of cable types and methods are employed to hard wire the camera to the monitor and transmit the video signal. These include:

Coaxial cable: It is so called because the conductors both share the same axis. A coaxial cable comprises of a centre core of solid or stranded copper known as the inner conductor. An outer screen is used to give shielding and a signal return.

Coaxial cable is good for relatively short distances. It is simple to install and maintain so is a good low cost solution. It is unbalanced and has a 6dB loss at 5.5MHz max.

Twisted Pair: In some situations coaxial cable is not cost effective or signal loss on the run can be unacceptable. A solution may be to use twisted pair.
Twisted Pair is for balanced line differential signalling with good noise immunity. It can be used for relatively long distance transmission.

A »

Dynamic range is the range of light that can be captured in a single image, from the darkest shadows to the brightest highlight. The high end of the dynamic range is limited by the charge capacity of the CCD. The low end of the range is limited by the noise of the electronics.

The importance of dynamic range

Many photographic scenes have a very wide dynamic range. If the dynamic range of the camera is smaller than the dynamic range of the scene, highlight texture and shadow detail will be lost.

A » Colour Cameras can be wall mounted. They require a mounting bracket which is sold separately.

A » The table below shows the estimated recording speeds and drive sizes to record for 30 days.

A » This table shows estimated recording in days. All times are calulated on constant recording on a 24 hours a day, 7 days a week basis. If using motion detection or scheduled recording, the record time will be increased.

A »

This can be achieved by using Internet Explorer. You will need your IP address to do this, please refer to the instruction manual for further details.

A » You will need to have your equipment networked together using the TCP/IP protocol.

A » To download a new firmware for your product, please click here for a link to our firmware section.

A » Unfortunately not. The unit you have may record and play back sound, but these are not included on the backup of the video.

A » Yes, these can be saved as files on your PC.

A »

No. The PDR-2160 Digital Video Recorders spot monitor outputs are single channel only.

A »

As well as LILIN, it is possible to control any dome incorporating the Pelco D protocol.

A »

You can view saved images on any Windows based PC.

A »

You will not need to purchase any additional software. All required viewing softwareis automatically installed to either a CDR or USB when images are saved.

A » Please click here to view instructions on how to update the installed version of Monitor.exe.

A » Please click here to follow the instructions on how to wire your PDR-2160 to multiple keyboards.

A » This depends on the product you are using, please see the technical manual supplied with the product, or click here to download a new one from the instruction manual section.

A » To get the auto pan feature to work with the high speed domes, you must have at least 2 presets programmed in to the dome. Once this has been done, it is just a case of pressing the auto pan button on the keyboard to start the auto pan, and press it again to stop it. When the dome is set in auto pan, you will not have any control over the dome until it is stopped.

A »
There are various ways to configure presets.

Unfortunately it is dependent on the products you are using. The easiest way is to refer to the technical manual provided with the domes, or click here to download the appropriate manual.

A » The expected life of an IR bulb is approximately 20,000 hours.

A » They are both types of Auto Iris Lens, where the mechanical opening of the iris is controlled by a motor in the lens. Where they differ is the signal or control given to that motor to adjust for the varying light levels.

A video Drive lens, as the name suggests, takes a 1.0Vp-p video signal from the camera to calculate, through a built in amplifier circuit, whether to open or close the iris.

A Direct Drive lens lets the camera make that decision and has no circuitry built in – the connections from the camera power the motor directly. Nearly every CCTV camera in production today has the facility to drive these types of lenses and as they are less expensive they are now the only type of lens you need to consider for external use.

For internal use you may have previously used manual iris lenses to save costs, but now the volume of Direct Drive Lenses being produced is so high there are unlikely to be any noticeable savings. Direct Drive lenses now account for 90% of our lens sales and the huge majority of those are varifocal, compared to 10 years ago the massive range of lenses you need to consider has reduced to just a few!

A » The F stop (aperture) determines the amount of light passing through the lens.

The lower the ‘f’ stop number the more light that can be passed through the lens during dark conditions which will produce better pictures at night.