CCTV Surveillance Cameras

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CCTV (Video Surveillance Cameras)

Increasing concerns around security have forced business and government bodies of all sizes to make significant investment in digital video surveillance systems. Originally created in the 1940’s for security in the banking industry, video surveillance has evolved quickly in the last decade to become the most popular form of security available.

As the IT industry has developed with rapid advancement in technology, video surveillance camera systems have experienced exponential growth since their introduction. Estimates show the CCTV surveillance cameras market to be worth $13B globally in 2009 with further growth between now and 2012 projected at more than 27%, indicating the immense growth potential of this market in the next few years.

In recent years, CCTV surveillance cameras have undergone a shift from analog to digital & IP systems with older tape based systems now being replaced with disk based and network attached systems that offer higher capacity, performance, high resolution images and redundancy within the systems. This transition has also allowed advanced options such as wireless networking, high resolution output, and colour systems, biometrics, smart sensors and intelligent analysis software. Whilst these new features have enhanced system performance and have proved highly valuable when incidents have occurred, they have also created a need for high capacity low cost storage for the images recorded. This is primarily in a RAID environment and based on SATA HDD technology which offers high capacity and redundancy at an acceptable price point.

Camera Technology

There are several types of camera used in today’s CCTV market.

Analog – Until recently most camera’s installed were analog, producing good quality images at an affordable price point.
Digital – The introduction of Digital Signal Processing (DSP) has increased both the flexibility of using security cameras whilst enhancing the quality of the colour images produced. The cameras offered today are feature rich compared to the older analog cameras making them the ideal choice for complex surveillance conditions such as those encountered in town centres.
IP Camera – The IP surveillance camera, typically have far greater resolution than analogue cameras, also know as a network camera; can be simply described as a camera and computer combined in one system.  Like a computer, the network camera has its own IP address, is connected directly to a network and can be placed wherever there is a network connection.

Video Recorders

Video recorders come as standalone and networked options with both offering their own distinct advantages. For example, since network video recorders (NVR’s) have no distance limitations, they are ideal for remote locations or for environments where cameras are widely distributed throughout a site. Digital video recorders (DVR’s), on the other hand are the best choice on a single site where analog & digital surveillance cameras are located only a few hundred feet from the station that the stores the images.

DVR – A DVR gives you the functionality of a traditional multiplexer together with an HDD device in place of tape, all housed in the same box together with some additional ports for connectivity.

The DVR provides a convenient, if limited, replacement for the multiplexer + VCR combination and provides non-linear access to recorded material usually selected by camera ID, time and date. The consistency of quality of recorded material will in general be higher than that obtained with analog tape although the actual quality achieved may or may not be better, depending on the compression algorithm and individual configuration.

In general more programmable options for individual video stream recording parameters, (picture resolution, number of frames per second, trigger options, start/stop times etc), are available, but a DVR is only useful where the analog cameras are all cabled back to the DVR’s location. Competent DVR’s now feature UDP (CAT 5) network ports so that the device can be provided with an IP address and thereby become accessible over an Ethernet network.
DVR’s can have some limitations around redundancy and a failure of the unit can lead to a loss of data and unlike an NVR which can be mirrored it is important that some form of backup is deployed with systems.

Storage DVR

Network Video Recorders

NVR – The network video recorder is the next natural step in the development of IP recording technology.

It is important to differentiate between DVR’s and NVR’s, as both are often termed ‘digital’. A DVR digitally compresses analog video feeds and stores them on a hard-drive, the term ‘digital’ referring to the compression and storage technology, not the transmitted video images. The DVR therefore has to be located near the analog feeds. In contrast an NVR stores digital images directly from the IP network.

Therefore the most obvious difference between the DVR and NVR is that whereas the DVR records from analog streams provided from analog cameras the NVR records video streams that have already been encoded at the cameras. Thus you find no video connectors anywhere on a NVR; it’s input and output is IP data comprising compressed and encoded video. This will typically be in MPEG-4 format which has enjoyed widespread adoption in the CCTV industry as the current compression technology of choice, due largely to its efficiency.

The huge advantage of architecture based on NVR’s is that they can be located anywhere on a network, at the monitoring centre, adjacent to camera clusters, on the edge of a network, collected together in a hardened environment, indeed anywhere at all. In use their location is transparent to an operator; you can simply call up the recorded video stream to be viewed from any location. Additionally NVR’s record and replay simultaneously, and recordings on any one machine can be remotely viewed by a number of authorized operators spread across the network simultaneously, all totally independently and without affecting each other.
Key features of NVR’s include features such as:

  • Hot-swappable disks
  • Simple Network Management Protocol (SNMP) support
  • Built-in diagnostics
  • Protection of files against deletion
  • In-built firewall for the protection of data against unauthorized access
  • File export function which embodies the watermarking and digital signature based on individual video frames and audit trail for security
  • Synchronized audio and video recording and playback
  • Hard-disk temperature monitoring
  • Dual, fully redundant power supplies and network connections, the latter providing uninterrupted and continued operation in the event of a single power supply or network failure
  • Mirroring capability for additional redundancy

Storage NVR

Storage Requirement

Many organisations now require video images are recorded and archived continuously from all cameras for 90 days or more. In large installations this can create a significant storage requirement and when you consider that users want this at the highest quality and maximum frame rate, it is not uncommon to have 200 terabyte and above installations. A prime example would be law enforcement applications where CCTV footage is required for evidential purposes. In these larger installations the storage element can dominate the overall cost of the system both up front and in management of storage servers, external RAID systems and network infrastructure.

Outside video resolution and frame rate the number of cameras is the main driving factor for storage growth in the CCTV market.  The average amount of digital data generated per day by a camera is 40GB at basic compression rates so a site with 100 cameras would be creating 4TB’s per day in data. When you multiply this by the average number of day’s data is required to be saved, 30 – 90 days, you are looking at a total storage capacity to be installed and managed of 120 – 360 terabytes.

When specifying and deploying storage there are several methods to consider such as distributed or centralised storage which decides whether the storage will be within the NVR’s or external in a SAN configuration. To clarify storage can be attached to the CCTV infrastructure in various ways using either direct attach methods using SCSI to SATA disk arrays, internally within the NVR by using a storage server that can process and store the images within the same system or finally in a SAN configuration using a standard 1U server as the NVR that is then connected to either a fibre channel or iSCSI SAN to give centralised storage.

All surveillance data can be seen as critical so there are various factors that will influence the storage used such as cost of hardware & management, video quality, CCTV application and existing network infrastructure.

Summary

CCTV today is being used for a variety of purposes since it came into its current digital form. From its conception with banking, where it is still used today, it has spread through many industries such as corporate offices, shopping centres and retail outlets, traffic control systems, casinos and hotels. However what haves really driven growth and adoption in CCTV installations is rising global security concerns. With a rise in terrorist strikes over the last 10 years it now seems unimaginable to see a place without CCTV, so it is no surprise that law enforcement and forensic applications have seen the quickest adoption in technology and storage capacity.