A comparison of CCTV technologies

Our world faces greater security threats than ever before and governments and commercial organisations are investing heavily in the security and safety of assets and personnel.

OFFERING a range of practical safety solutions that have proved indispensable to first responders and investigators, the video surveillance industry is in the midst of a period of enormous expansion. New products and new surveillance solutions with improved performances and reliabilities are continuously appearing on the market. But having so many options leads installers and integrators to another problem.

To begin with, there are 6 video surveillance (CCTV) technologies on the market: Analogue CCTV, IP (Network), HD-SDI (High Definition Serial Digital Interface), AHD (Analogue High Definition), HD-CVI (High Definition Composite Video Interface) and HD-TVI (High Definition Transport Video Interface).

Analogue CCTV Technology

Let’s start with analogue CCTV technology, considering its strengths and weaknesses.

Strengths:

• Analogue CCTV is a stable and well-established robust technology which is supported by all major CCTV manufacturers. It is easy to install, setup, operate and maintain and cost effective. There are no compatibility issues among the cameras and DVRs and there is no loss of frames and no delays in live viewing of cameras.
• Analogue CCD cameras demonstrate better performance in low light conditions, than megapixel CMOS cameras

Weaknesses:

• By far the biggest weakness is the limited image resolution with a maximum recording resolution of D1 which is (704 pixels x 576 pixels, or about 0.4 MP).
• The quality, reliability and security of its wireless transmission is inferior and less secure than other IP technologies.

IP (Network) Technology

Now let’s take a look at IP video technology, which covers cameras, storage solutions and software solutions supporting them.

Strengths:

• This technology can achieve megapixel resolution of images which results in excellent clarity and crystal clear picture. Zooming in x2 or even x16 of a playback or live image will still provide useful and clear image.
• The same CAT5/6 network cable is shared for the video transmission, control data and power supply to the cameras. No other cables are required for the installation.
• It is relatively easy to remove, replace or add new cameras into the system and maintain and upgrade the firmware of the IP cameras and IP Technology allows a variety of data storage options including redundant storage and remote storage.
• Many network recording software apps are powered with intelligent search based on operator’s requirements as well as digital zoom with good quality

Weaknesses

• IP camera performance under low light conditions is significantly inferior to its analogue counterparts and IP CCTV systems are more fragile than analogue ones, because they rely heavily on the network infrastructure. If the network goes down there will be no live video monitoring neither recording by the NVRs.
• Because of the packetised nature of the IP network data transmission there will be always a delay in the video signal. This delay can be in magnitudes of 10 or 20 seconds and is especially noticeable while viewing all cameras simultaneously in real time at higher resolutions.
• Installation of a large IP CCTV system requires lots of initial planning and extensive knowledge in computer networking as well as IP video. If not designed and specified properly, the system will suffer from latency, delays and missing frames. If that is the case, even simple operations like a simultaneous play back of 2 or more cameras will be very slow and frustrating for the security operator. Bear in mind that missing frames from a video stream mean missing frames from streams recorded on the NVR, so there is a probability that some important events may not be recorded at all.
• There is a limitation of 100m maximum cable run between the network nodes and IP cameras require much more storage space.
• The cost to build, setup and maintain the IP system is much more than any other CCTV system.

HD-SDI (High Definition - Serial Digital Interface) Technology

Now we come to high definition serial digital interface technology, or HD-SDI, which is digital solution that uses the same cabling as analogue solutions, making it ideal for retrofits.

Strengths

• High definition video that can go up to 2MP of resolution (1920 x 1080) pixels and is relatively easy to install, setup, operate and maintain.
• The video signal is transmitted directly from the camera to the DVR with no latency and there is 100 % guarantee of no loss of frames or any video recordings in general.
• SDI technology should use the same kind of cables as the analogue CCTV system but the catch is that they have to be in a good condition.

Weaknesses

• Despite being a cheaper alternative to the IP CCTV systems, SDI equipment cost is still too high and there is a limitation of max 100m cable runs between the camera and the DVR
• Video signal transmission is susceptible to electrical noise and electromagnetic Interference
• Requires much more storage capacity than analogue CCTV

HD Analogue CCTV Technologies (AHD, HD-CVI and HD-TVI)

All 3 HD Analogue technologies, which include Analogue High Definition (AHD), High Definition Composite Video Interface (HD-CVI) and High Definition Transport Video Interface (HD-TVI), have similar characteristics.

Strengths

• The technology is very similar to analogue CCTV. All cameras are directly connected to the associated DVR
• It utilises the same 75 Ohm coaxial cable as the analogue CCTV technology is using, but instead of transmitting only video it transmits simultaneously 3 signals together - video, audio and serial data
• Transmitted signals are immune to external electromagnetic interferences
• Maximum distance between camera and DVR is 500m
• It achieves instant signal transmission with no compression, no latency and no delay
• Delivers HD quality video image. Supports 720p (1280 x 720 pixels) and 1080p (1920 x 1080) pixels, that’s full HD
• Complies with open standard which guarantees compatibility among the devices from different manufacturers with the same technology
• Low ownership and maintenance cost. Almost the same cost as for the good old-fashioned.

Weaknesses

• Relatively new technology and still not widely accepted by the major CCTV manufacturers
• The technology is not supported enough with as many software applications as analogue CCTV and IP technologies are
• Integration with complex integrated access control/intrusion systems is very limited because of the lack of support from the major developers and manufacturers
• Maximum video resolution can only go to Full HD (1920 x 1080 pixels)