What a CCTV system really is?
CCTV - Closed -Circuit Television - it is usually a system of image transmission from camera to a designated set of monitors or DVRs, in a limited area, to ensure security of the site. It can be a single building , such as a bank , market , school, as well as group of buildings such as airports, large factories or entire cities.
CCTV systems aplication
The original and still the main purpose of CCTV systems is to improve the safety . CCTV systems installed in banks , shops, post offices, and other smaller buildings with public access, can help with face recognition and thus to identify the person who tries to rob these institutions, or any persons present in monitored area. In such situations CCTV systems can be used to accurately reconstruct what has happened.
Monitoring of major institutions such as airports , railway stations , bus stations , etc. in addition to the aforementioned applications can be used for the analysis of the terrorist attack , the identification of persons involved therein and to ,in the future, more quickly respond to similar situations . CCTV installations in such places are useful to track the escape of wanted person and to stop them.
More and more cities choose to monitor streets, parks , housing estates in order to capture any violations of law, accidents or unforeseen incidents like fainting or loss of consciousness. In such cases, they can immediately react and inform relevant authorities . Due to high camera dispersion and long distances wireless video transmission systems are being used as well as telemetry systems for PTZ camera or DVR control.
Some certain explication of CCTV is widely understood streets monitoring. The composition of this may include DVRs located in marked and unmarked police cars , cameras at intersections , traffic lights and cameras in a high-traffic road . Despite various opinions on traffic monitoring , appropriate cameras and recorders locating gradually, but effectively reduces the amount of unwanted traffic incidents.
Positive effects of cctv encourage many people to install such systems in their own private homes or apartments. In addition to the obvious control of empty apartment when owners are at work or on vacation, monitoring is also helpful when householders are asleep or were stunned . However, in such situations, CCTV has to be well hidden , or wireless CCTV receiver should be placed in another location, away from the apartment , such as security company .
Another new possibility to access the image from external location are web services where you can send video from IP cameras located at home. Easy access for large number of people increases possibility of quick noticing any violation acts taking place at your home. You should keep in mind that this option gives opportunity to view your life to all people with access to internet, so home view should be password secured. People wishing to invest in such IP should give the password only to selected group of people.
Is it worth?
Several studies were carried out regarding the effectiveness of CCTV in crime preventing , concrete results were divergent, but had similar tendencies. In areas where the density of cameras was greater and the amount of people smaller, like small car parks , crime has fallen by more than a half, comparing to period before the site was monitored. In areas where cameras concentration was smaller and amount of people greater, like railway stations, crime has fallen by a few percent.
Another role of CCTV security is also monitoring of production lines located in large factories. That enables fast detection of any malfunctions which jeopardize the safety. The use of digital wireless video transmission kits allows to install the CCTV system in locations, where wired installation is not possible , such as cranes , elevators, or ferries. Another reason for such type of monitoring are the conditions under which the manufacturing process is performed , i.e. high temperature, dust or toxic gases or liquids.
What to look for?
People and institutions wishing to build a CCTV system usually concentrate on the price. However, low initial price may, within a few first years, may turn up a lot higher due to frequent replacement of damaged elements of the installation, much higher than if we had originally invested in more expensive, but better quality equipment. When taking into consideration possible losses, such as theft or production downtime due to system failure, price might be even several times higher.
Additional priority for some people from CCTV field is image quality, so HD transmission becomes a must. It happens that such requirements cannot be met by existing installations prepared for simple analogue systems . In such situations wireless HD transmission may help i.e. using wireless HD video kit such as CDS - 5HD - SDI, what turns to be much cheaper , faster and easier than replacing the entire wired system or renting facilities from third parties.
A consequence of the increasing popularity of CCTV systems is fact it can be installed in areas where they were not originally planned . In such places we have lack of necessary infrastructure, like cables, and sloshing walls or digging up the parking is not a solution. It would require major investment and exactly in such places wireless transmission solutions are being sought.
Wireless CCTV systems can be divided into several groups. The simplest FM modulation systems transmit analogue video signal i.e. TCO5807h. Such kits require clear line of sight between transmitter and receiver. Advanced kits convert signal from analog to digital and using OFDM modulation send it to receiver where the signal is being converted back to analogue i.e. CDS5021h. The most advanced and resistant to interference systems are completely digital , where HD signal using OFDM modulation is transmitted to receiver and then continuously to monitors and DVRs, i.e. CDS-5IP.
To wireless CCTV systems we also classify wireless telemetry systems which enable remote control of PTZ cameras or DVRs, i.e. CD04.
Operating frequency wireless systems
Each of wireless transmission kits operate on license free radio frequency 5GHz - allocated to us by the European Union - which supplanted earlier available , but currently very heavily used 2.4GHz band. Less frequently used telemetry systems use much lower frequencies – 869MHz.
CCTV surveillance systems become more and more popular in cities , neighborhoods, companies and even in our homes. Thanks to continuous development of this sector we are able to meet even most demanding customers requirements. This also happens because of the growing awareness of benefits in terms of security, not only of property, but also health and human life. Possibilities given to us by wireless video transmission systems allow to install CCTV surveillance in areas where previously it was very difficult or impossible.
Piotr Grenda, CAMSAT