FAQ Overview
All FAQ from the category CCTV Systems
What is CCTV?5Rating:
Closed-circuit television (CCTV) is the use of video cameras to transmit a signal to a specific place, on a limited set of monitors or viewers.
It differs from broadcast television in that the signal is not openly transmitted (athough it may employ point to point wireless links). CCTV is often used for surveillance purposes in areas that may need monitoring such as banks, casinos, airports, military installations, homes, offices and retail stores.
In industrial plants, CCTV equipment may be used to observe parts of a process from a central control room; when, for example, the environment is not suitable for humans (toxic gases, high heights etc).
CCTV systems may operate continuously or only as required to monitor a particular event. A more advanced form of CCTV, utilizing Digital Video Recorders (DVRs), provides recording for possibly many years, with a variety of quality and performance options and extra features (such as motion-detection and email alerts).- Video Camera Technology (Analogue vs Digital)5Rating:
Basically video cameras are classified into the following 2 main types: (1) ANALOGUE and (2) DIGITAL.
(1) Analogue Cameras
In older days, most analogue cameras were cabled to record straight to a video tape recorder which was able to record analogue signals as pictures. If the analogue signals are recorded to tape, then the tape must run at a very slow speed in order to operate continuously. This is because in order to allow a 3 hour tape to run for 24 hours, it must be set to run on a time lapse basis which is usually about 4 frames a second. In one second, the camera scene can change dramatically. A person for example can have walked a distance of 1 meter, and therefore if the distance is divided into 4 parts i.e. 4 frames or 'snapshots' in time, then each frame invariably looks like a blur, unless the subject keeps relatively still.Technology improves and nowadays, analogue signals are converted into a digital signal to enable the recordings to be stored on a PC as digital recordings. In that case the analogue video camera must be plugged directly into a video capture card in the computer and the card then converts the analogue signal to digital. These cards are relatively cheap, but inevitably the resulting digital signals are compressed 5:1 (MPEG compression) in order for the video recordings to be saved on a continuous basis.
The most common way to store recordings on a non-analogue media is through the use of a digital video recorder (DVR). Such a device is similar in functionality to a PC with a capture card and appropriate video recording software. Unlike PCs, most DVRs designed for CCTV purposes are embedded devices that require less maintenance and simpler setup than a PC-based solution, for a medium to large number of analogue cameras.
Some DVRs also allow digital broadcasting of the video signal, thus acting like a network camera. If a device does allow broadcasting of the video, but does not record it, then it's called a Video Server. These devices effectively turn any analogue camera (or any analogue video signal) into a network camera.
(2) Digital Cameras
Digital cameras do not require a video capture card because they work using a digital signal which can be saved directly to a computer. The signal is compressed 5:1, but DVD quality can be achieved with more compression (MPEG-2 is standard for DVD-video, and has a higher compression ratio than 5:1, with a slightly lower video quality than 5:1 at best, and is adjustable for the amount of space to be taken up versus the quality of picture needed or desired). The highest picture quality of DVD is only slightly lower than the quality of basic 5:1-compression DV.
Saving uncompressed digital recordings takes up an enormous amount of hard drive space, and a few hours of uncompressed video could quickly fill up a large hard drive. Holiday uncompressed recordings may look fine but one could not run uncompressed quality recordings on a continuous basis. Motion detection is therefore sometimes used as a work around solution to record in uncompressed quality.However, in any situation where standard-definition video cameras are used, the quality is going to be poor because the maximum pixel resolution of the image chips in most of these devices is 320,000 pixels (analogue quality is measured in TV lines but the results are the same); they generally capture horizontal and vertical fields of lines and blend them together to make a single frame; the maximum frame rate is normally 30 frames per second.
That said, multi-megapixel IP-CCTV cameras are coming on the market. Still quite expensive, but they can capture video images at resolutions of 1, 2, 3, 5 and even up to 11 Megapixels. Unlike with analogue cameras, details such as number plates are easily readable. At 11 Megapixels, forensic quality images are made where each hand on a person can be distinguised. Because of the much higher resolutions available with these types of cameras, they can be set up to cover a wide area where normally several analogue cameras would have been needed.
- Types of Cameras5Rating:There are various forms of camera that are presently available in the market. The common one are listed below:
fTYPE PICTURE DESCRIPTION Indoor Dome Color Camera 
This kind of cameras are suitable for indoor usage and requires a minimum amount of light ambience in order to obtain visibility in signal. The low light condition is measured in Lux which is the SI (International System of Units) unit of illuminance and luminous emittance and depending on the quality of the camera, some dome cameras are known to be able to capture images as low as 0.002Lux condition (0Lux is total darkness condition). Indoor IR Dome Color Camera 
This kind of cameras are equipped with IR (Infra-Red) LEDs that enable the camera to capture images even in 0Lux (total darkness) condition. The distance of viewing coverage of normal range of IR dome cameras during total darkness ranges from 5 metres to 10 metres, depending on the quantity of IR LEDs mounted in the camera. When the light ambience is sufficient, the output image will be in color and when the light goes off, IR functionality kicks in and the out image will be in black and white. Outdoor Bullet-type (tube) Color Camera 
This kind of cameras are suitable for outdoor usage and requires an additional external case enclosure to keep the camera intact from the weathers. The main advantage of this type of camera is that the lens are changable from fixed lens to varifocal (zoom) lens. Depending on the lens and functionalities built-in, these kind of cameras can work as a Day Only Camera or Day & Night Camera. Outdoor IR Bullet-type (tube) Color Camera 
This kind of cameras are suitable for outdoor usage and comes equiped with IR LEDs for 0Lux (total darkness) monitoring and it is relatively economical in cost as compared to the abovementioned counterpart. However, the lens of this type of outdoor camera cannot be changed and the whole unit is usually sealed tight to conform to IP66 outdoor weather-proof standards. PTZ (Pan-Tilt-Zoom) Camera 
PTZ is an acronym for Pan, Tilt and Zoom and refer to the features of this kind of camera. The camera is able to be controlled remotely to pan 360°, tilting up or down and zooming in the target view. Most of the PTZ cameras allow user to zoom 23x or more depending on the brand of the camera. Additional cable (other than the power & signal cables) is needed to control the PTZ functionality which can be either connected to a PTZ keyboard or DVR directly. - Types of CCTV Lenses5Rating:
There are mainly 3 types of lenses, which are Fixed Focal Length lenses, Variable Focal Length (Vari-focal) lenses and Zoom lenses. The focal length of a lens defines its effective viewing angles both horizontally and vertically.
Vari-focal lenses - Often it is not possible to determine the focal length of a lens required to meet a particular application or perhaps the angle of view is not provided by one of the standard lenses available. Hence, narrow range, manually zoomed lenses have been developed to meet these application needs. These are known as 'Vari-Focal' lenses and are available in a number of different configurations. The exact angle of view will have to be set on installation.
Zoom lenses - For CCTV applications, these are motorised type of lenses to enable zooming and focusing of the lens from remote control positions. Zoom ratios are the ratios of maximum to minimum focal length. Nearly all zoom lenses used in CCTV applications are auto-iris type.
Most CCTV lenses are equipped with an iris that consists of four or six opaque metal vanes which are arranged to give a roughly circular hole or aperture through which light can pass and then fall on the camera sensor surface. The vanes can be driven together to alter the size of the lens aperture to control the amount of light falling on the sensor and hence alter the picture brightness.
And the control methods of the iris are mainly classified into the following 3 kinds:
1. Manual Iris Lenses
The simplest type of iris control is termed 'Manual Iris'. The lens is equipped with a ring on the body that can be turned to alter the aperture directly. In CCTV systems this can only be used generally in fixed lighting conditions and it is not convenient to continually adjust the lens for correct picture brightness.
2. Auto-Iris Lenses
A far more common arrangement is the use auto-iris lenses where the iris vanes are controlled by a servo motor which is controlled by an 'iris-amplifier' circuit within the lens. Hence an auto-iris lens is used where the lighting level is liable to continous changes.
e.g. Outdoors where lighting can change from full sunlight down to near total darkness.
3. Direct Drive Lenses (FCS)
These are a development on auto-iris lenses where the motor moving the iris panes in the lens are driven by the camera itself, hence 'Direct Drive'. There are no active electronics in the lens and hence they are simpler, smaller and cheaper than an equivalent auto-iris lens. They must be used with a camera capable of driving 'DD' lenses and this is commonly identified by the presence of the characteristic 4-pins square 'Hi-Rose' (Panasonic) plug on the side of the camera. - Does the CCTV system allows remote viewing?5Rating:
Definitely yes. Mostly all Digital Video Recorders (DVR) are network-ready and as long as you have internet service in your premises, you will be able to connect the DVR to your internet router for remote access functionality.
However, do take note that while remotely viewing the CCTV system is possible, there are a few technical factors which we shall highlight here:
1. The speed and response of the CCTV system when viewing remotely depends mainly on the speed of the internet connectivity. We recommend a minimum of 512kbps broadband internet access speed.
2. The internet router must be configurable and supports Port Forwarding and Dynamic DNS updating.
e.g. Singtel 2wire MIO router is known to be unable to recognise the DVR device and therefore, no port can be forwarded to the DVR by the router.
3. Broadband internet services mainly comes with dynamic or static IP address. Static IP makes configuration simple as your internet IP address of your router does not change and you can access your DVR anytime as long as the internet service is up and running.
Dynamic IP internet services means that the Telco will refresh your assigned Internet IP address for your router every once a while. This makes it slightly more troublesome to know what is your currently assigned IP address for your router. A way to solve this issue is to assign a Dynamic DNS hostname service to your router. This means that we will assign an URL (e.g. cctv.dyndns.org) to you and configure your router to auto-update your router's current assigned IP address to this URL. So whenever your internet IP address changes, the URL (cctv.dyndns.org) will know of it's changes and change accordingly. You will just need to remember to access your CCTV system via the URL and let the router do the rest of the monitoring.
4. Web-based access of the CCTV system required ActiveX components to be installed in order to view the CCTV system. ActiveX is introduced by Microsoft and mainly compatible without much issues with Internet Explorer. Other browsers such as Chrome from Google are not supported. First time accessing of the CCTV system on a new computer will take slightly longer than normal as the browser need to download the ActiveX component and install it first before you can view the images.
5. Central Management Software (CMS) are available for major established brands which you can install in replacement of using the internet browser to access your CCTV system remotely. The major advantage is that the CMS software allows you to connect up to more than one remote CCTV system. This is extremely useful for retail outlet establishments where a single screen to monitor all of their outlets at one time is possible. - Can the CCTV system be monitored using mobile phones?5Rating:
Mostly NO. The reason is that to access the CCTV system, we either use the web-based access (i.e; Internet Explorer) or application-based access (i.e; CMS software, Video Viewing Software or Mobile Software if there's one).
Although mobile phones are equipped with internet browsing functionalities, however the web access method required the internet browser to install an ActiveX script which currently are not supported in mobile version of internet browsers.
As for mobile video viewing software, it is written in Java programming and requires a mobile phone that support Java Software installation, which means that only smartphones running the Symbian Operating System (eg. Nokia Communicator) allows external software downloading and installation. Coupled this with the fact that only selected few manufacturers have went through the trouble to develop a mobile software for their DVRs, the chances of getting a DVR that happens to support the mobile phone that you are currently using may be remote.
However, with the increasing popularity of iPhone by Apple and Android powered phones by Google, there are several technology vendors that have developed Apps that can control selected range of DVRs. One of the Apps is Total Control Vidcam which can control a list of tested DVRs. For non-specified brands & models, a test will be performed by the company who will attempt to view your DVR and capture footage. However, this App comes with a hefty price tag for your consideration. A low-end netbook might be more economical to invest your money in order to achieve remote viewing at maximum mobility lifestyle.