Close-Circuit Television (CCTV)

Close-Circuit Television is the use of a group of video cameras to transmit signals to specific places.The difference between broadcast television and the CCTV signal is that the signal is not open transmitted, it commonly uses point to point wireless links. These systems are often used for surveillance in areas that may need monitoring. One can find these systems in places like casinos, airports, grocery stores and so on.

Moreover, CCTV systems might be use to monitor parts of process in industrial plants, when the environment is not appropriate for humans. Some CCTV systems use DVR’s (Digital Videos Recorders), providing the opportunity to keep record for many years. We can also find system with more complex features such as motion detection and email alerts. CCTV systems are also use for public surveillance on streets. UK is the country with more cameras per person.

First CCTV system was installed in Peenemunde, Germany in 1942 by Siemens AG. These systems are still being used at modern launch sites to record the flight of the rockets, in order to find the possible causes of malfunctions.

In 1968, New York City was the first city in the United States to install video cameras to monitor the streets and fight crime. Later the use of theses system became really common in banks, stores and other business to record evidence of criminal activity.

In the last years public space surveillance has became more popular because of the increase in crime fears.

 Storage and Data preservation

Data storage is an important part of CCTV systems.  Videos are kept for several reasons; in case we need to recover evidence of any important activity, data would be kept and arranged historically providing easy access to it. Some re-usable media such as tape might be used in the recording process; the problem using this type of media is that the time of retention of the data is limited.

Mostly, recordings are kept or stored using hard disk drives instead of video tapes. The quality of digital recordings is subject to compression ratios, these ratios may vary depending on the compression standard, images stored per second, image size and retention.

Internet Protocol Cameras (IP Cameras)

These type cameras allow users to view their cameras from anywhere as long as they have internet access.  They are called IP cameras because they use IP protocol to establish internet communication and provide worldwide access to the users.  IP is the principal protocol in the Internet Layer; this protocol delivers data packets from the source to the destination based on addresses.

Some advantages IP cameras offers are:

• LED lighting: this feature is also known as night vision; it provides a better view in low light areas.
• Better image quality: some IP cameras have a 640x480 resolution and are capable to record at 30 frames per second.
• Wireless connection:  they are able to operate on wireless networks connecting them through a router.

There are also some disadvantages in these cameras:

• Higher initial cost
• Less choice of manufacturers
• High bandwidth requirements
• Vulnerable to hacking via internet