CCTV Illegal (90%) Ineffective (80%)

Whether CCTV is an existing element of your security/management strategy or you are considering investing in CCTV, you need to be sure that the system will provide unequivocal evidence.

Imagine your frustration at having your CCTV evidence rejected in a health & safety claim or employment law dispute due to poor quality images or procedural mistakes. The financial impact of such cases could amount to tens if not hundreds of thousands of currency; by comparison most instances of theft can appear almost inconsequential in terms of loss.

The quality of images as seen on TV News and crime reporting programmers is a damning indictment of CCTV standards. Consider the numbers quoted in the headline, 90% Illegal stated by CameraWatch is based on ‘initial research’ and refers to total or partial shortfall in Data Protection Act compliance. 80% Ineffective refers to the efficacy of CCTV evidence examined by the Police and is stated in the Home Office National CCTV Strategy.

These statistics are largely based on anecdotal evidence, nevertheless practical experience of those professionally involved in the assessment of CCTV systems would broadly agree with these estimates.

Another interesting number is the 3.2 to 4.2 million CCTV surveillance cameras employed in the India. Which figure is closest to reality no one knows, but there is probably 1 camera for every 15 members of the population, capturing our images as we go about our lives.

According to current folklore our image is captured 300 times a day and stored for a month or more. Should we be worried?

Provided that CCTV images are managed in accordance with Data Protection Act principles and you are a law abiding citizen, there should be no concern and in countless high profile cases CCTV has proven to be an invaluable aid to investigation. Evidence of the immediately preceding terrorist bombings was of fundamental importance to the Police investigation.

Data Protection Act legislation is at the very core of protecting our Human Rights when it comes to the use of CCTV, so are we safe to assume we are protected from its misuse? The law is certainly adequate and has been since the 1998 Data Protection Act encompassed CCTV images. The Information Commissioner is responsible for enforcement and serious cases of non compliance can result in a substantial fine or even a custodial sentence.

You must let people know that they are in an area where CCTV surveillance is being carried out. The most effective way of doing this is by prominently placed signs at the entrance to the CCTV zone and reinforcing this with further signs inside the area. The signs should contain details of the organization responsible for operating the system, the purposes for using CCTV and contact details.

The Data Protection Act does not prescribe any specific minimum or maximum periods which images should be retained for, the archive period should reflect the organization’s own purposes although 30 days is the accepted norm.

A little known aspect of DPA law is Right of Subject Access, you have a legal right to request a copy of your images captured on CCTV and subject to certain reasonable conditions the organization responsible for the CCTV system (the Data Controller) must provide a copy.

You will need to make the application in writing: stating where you were, the time & date and provide photographic identity so that the relevant images can be searched for. The Data Controller is entitled to charge something for the search including the cost of providing a CD or DVD. The images must be provided to the applicant within 40 days of the date of application or a valid reason for not being able to comply must be given within 21 days.

Legislation is weighted in favor of the applicant and the Data Controller can incur substantial costs in producing the copy recording, particularly if it is found to include images of third parties as well as the applicant. These third party images must be masked in order to protect the identities of others.

A frequent dilemma faced by Security / Facilities Managers of multi tenanted buildings is when a tenant demands access to recordings that may assist them in criminal or civil law matters. In the case of criminal investigation the response is clear cut, the tenant must report the matter to the Police who will request a copy of any video evidence they may require.

Non criminal cases are more complex and disclosure of images directly to the tenant may result in a breach of Data Protection Act law, on the other hand refusal may result in bad feeling if tenant holds the reasonable view that; ‘security is included in the service charge that I am paying and I should be allowed access to CCTV recordings that relate to my business’.

A reasonable response would be to establish the parameters of the recording; date, time and cameras. Then download images in the same manner as for a criminal investigation, but without allowing the applicant to view the images. You have at this point protected the required images from being overwritten by the recording equipment. The next move is to suggest that the tenant instruct their lawyer to request a copy, subject to an undertaking that the law firm becomes Data Controller for the issued copy.

In this article we refer to digital recording only, on the basis that video tape is redundant technology that is no longer serviceable and unlikely to be effective.

Digital images are primarily recorded to hard drive and are only downloaded on demand, the recording equipment should be held in a secure enclosure fixed to the building fabric or located in a security control room. Access to the system to download images should be password protected and only available to nominated Data Processors.

Images should be downloaded to non rewritable media such as CD or DVD and be playable on any video enabled PC or laptop without the need for additional software. It is good practice to download two copies of an incident, one being the Working Copy for issue and the other being an Archive copy held securely on site for backup or verification purposes. It is vital that a robust audit trail is created by means of Unique Reference Numbers printed on the disc during the printing process. The audit trail should be supported by suitable documentation. Download to memory stick, re-recordable media or the internet without secure encryption will compromise the veracity of the evidence.

If CCTV is an existing element within your security & management strategy, make sure that you have a CCTV policy in place describing how it should be managed in compliance with Data Protection Act law. Don’t then file and forget, but ensure that your security staff are issued with a copy and carry out an annual assessment of management and equipment performance, thereby ensuring that your CCTV continues to meet current needs and best practice.

If you are considering the installation of CCTV get a professional to assess your risks and system requirements in the form of an Operational Requirement based on the Home Office model. This is in effect a performance specification that can be issued to those responsible for the technical design and bid process, you can thus be sure of obtaining comparable quotations on which to base your buying decision. Furthermore you will have created a benchmark against which performance can be objectively assessed as a part of an effective professional handover process that will include; System Operating Manual, CCTV Policy, Management Documentation, Statutory CCTV Warning Signs and training of those responsible for managing the system.

Products Designed to Provide Home Security

When it comes to protecting your home and your loved ones, you really can't be too cautious. To help homeowners protect the things they cherish, manufacturers of home security products have made a variety of different systems available for use.

Home Alarm SystemsProbably the most used systems for home security are those which come with alarms. The most basic alarm system is a simple device which attaches to an entrance. This economical alarm is usually placed on the front entrance to the home along with a warning sticker informing any would be intruders of the home's protection. On a larger scale, alarm systems can include multiple alarms wired to several entrances as well as first floor windows.

Home security systems with alarms can also include other devices for monitoring the area. Motion sensor cameras and outdoor security lights can be connected to an alarm systems so when they detect motion in the area, the alarms will sound. Some indoor systems use infrared lights to detect motion in the area, which in turn will sound the interior alarm. Alarms are available with different decibel levels making them audible for different ranges. An inexpensive front door alarm will usually be audible to everyone inside the house and possibly to the next door neighbors.

Fake Security DevicesSome people want the security of having deluxe systems installed, but do not have the funds available to invest in these systems. One way to scare off possible intruders is to purchase fake security equipment. Most of the fake items are designed to look like real security cameras. The outer casing is identical to all of the most common types of security cameras, but the inside is empty. These fake cameras come with mounting hardware so they can be attached to any outside wall.

Homeowners can also purchase signs and stickers indicating there are security devices installed on the premises when in fact, there is not. Many people purchase these signs and stickers and place them in their yards and on their doors and windows to deter any potential intruders.

Home Improvements for SecurityIn addition to the alarm and home automation system homeowners can purchase for security, there are also home improvements which can help make a home harder to break into. Replacing screen or service doors on entrances with wrought iron doors will make it much harder for intruders to enter. These doors are made with wrought iron bars designed in attractive styles so they add appeal to the outside of the home.

Installing windows that have interior latch locks can also make them harder to open from the outside. Front doors and garage door sensor can have electronic keypads installed to replace traditional key locks. Keypads require the person to enter their special code number in order to unlock the door. Installing outdoor lights around entrances and on garages will also add protection to a home when the lights are connected to an automatic timer designed to turn them on in the evenings whether you are home or away.

Edge Recording in CCTV System

What is Edge Recording?

Edge recording, also called local storage or on-board recording, is when a camera records video directly onto a SD or memory card in the camera instead of a separate NVR or storage device. Edge recording gives you more flexibility in recording video.

How Edge Recording Works

Saving video files on an on-board memory card is called edge recording because the file location is on the “edge” of the surveillance system network where the camera is located, instead of a “central” location like a NVR where all cameras and other devices are connected.

The SD cards surveillance cameras use can have limited space compared to large computer hard drives or NVRs, making them a great solution when you only want to record small numbers of files. Motion detection-activated recording, where your camera only records if it detects motion and can go long stretches of time between recorded events, work well with edge recording.

Edge recording is also an alternative to larger storage systems if you’re on a budget. While you will need to purchase the SD card separately from the camera, NVR systems can be more expensive and intensive than you need if you don’t save many files.

How Edge Recording Can Help You

Edge recording provides a cost-effective storage system for small systems. But it can also add flexibility to your system, and provide a backup storage method. While specific features will vary by manufacturer, edge storage can:

·         Record files to the memory card in the event that the connection to the central NVR is lost

·         Store video for cameras that cannot easily connect to a central NVR, including remote locations and mobile camera systems

·         Minimize bandwidth by not sending large video files over your network

When used as the main storage location for small video files or as part of a larger system for saving and retrieving files, edge recording is used by many industries and system installers:

·         For businesses who only save motion-activated video at night when the office is closed

·         For home owners, who only record when they are out of the house

·         For public transportation, included busses and trains, who cannot stay connected to a central NVR while traveling

Edge recording is available on cameras from all major surveillance camera brands includingAxis, Optica, and Mobotix.

Capturing Crystal Clear Images With Megapixel Technology

Megapixel surveillance is not a new concept — its applications and benefits are starkly clear. What has changed are smarter cameras, taking advantage of the added pixels and a better understanding of illumination in real life. In the first of a two-part report, A&S examines how smarter megapixel cameras are getting; the second part looks at best practices for optimal performance.

The big picture for megapixel surveillance cameras looks bright, in the wake of the recession. HD and megapixel cameras are expected to make up nearly 30 percent of network camera shipments in 2011, according to IMS Research. By 2015, it is forecast that more than 60 percent of network cameras shipped will be of megapixel resolution.

The resolution increase has a noted effect on the whole surveillance system. While a 2.1-megapixel or 1,080p HD image is six times larger than a D1 image, the additional pixels require a bigger pipe to transmit more data. The infrastructure and storage costs for megapixel are well-documented, with ROI and TCO being used as arguments in favor of bigger pictures. The fate of megapixel is linked to the future of IP networks, with HD forecast to make up most high-resolution cameras compared to megapixel, according to IMS.

Megapixel surveillance requires careful planning, but the benefits of added resolution boost the accuracy of analytics. Edge devices take advantage of faster processors, resulting in smarter use of pixels. Analytics can help reduce bandwidth, as an event will trigger video streaming, rather than constantly sending the same still images over the network. A more distributed architecture puts less strain on networks and makes life easier.

Clarity is the main driver for megapixel. “At the end of the day, you're putting in a security system to protect life and provide evidence in a court of law,” said Stephen Moody, Security Development Manager for ViS Security Solutions, an integrator in Ireland.

Cracking the Code
H.264 is the de facto standard compression for megapixel cameras, due to its efficiency in crunching large data files into smaller ones for transmission and storage. As compression evolved from M-JPEG's stills to MPEG-4 and now to H.264, a variety of profiles yield differences in performance. With 17 profiles in all, three are the most common: baseline, main and high, said Sachin Khanna, PM for CCTV, Bosch Security Systems.

By profile, the baseline is appropriate for video conferencing; the main profile is good for broadcast video; and high profile is most applicable for HD broadcast video. “H.264 requires a fair amount of processing power for encoding and decoding; this may limit the camera's frame rate and dictate the NVR platform to achieve the desired performance,” said Rich Pineau, CTO of Oncam Global.

Most H.264 profiles stem from 2-D applications, with not all profiles being capable of integration. “Even if both cameras are H.264 and the manufacturers are partners, the system could still not work,” said Patrick Lim, Director of Sales and Marketing for Ademco Far East. “The I/O and output are hard to integrate. Some engineers say it's easy to plug and play — there's no such thing.”

Security Camera Selection Guide

ON Sunday, November 8, 2009 we discuss a Guide for choosing the CCTV system, now we know how to select a Security camera.( http://arindamcctvaccesscontrol.blogspot.com/2009/11/guide-for-choosing-cctv-system.html )

Security cameras are literally the eyes of a video surveillance system. Cameras should be deployed in critical areas to capture relevant video.
The two basic principles of camera deployment are (1) use chokepoints and (2) cover assets.
Chokepoints are areas where people or vehicles must pass to enter a certain area. Examples include doorways, hallways and driveways. Placing cameras at chokepoints is a very cost-effective way to document who entered a facility.
Assets are the specific objects or areas that need security. Examples of assets include physical objects such as safes and merchandise areas as well as areas where important activity occurs such as cash registers, parking spots or lobbies. What is defined as an asset is relative to the needs and priorities of your organization.

1. Security Camera Selection

Once you determine what areas you want to cover, there are four camera characteristics to decide on:
1. Fixed vs. PTZ: A camera can be fixed to only look at one specific view or it can be movable through the use of panning, tilting and zooming (i.e., moving left and right, up and down, closer and farer away). Most cameras used in surveillance are fixed. PTZ cameras are generally used to cover wider fields of views and should generally be used only if you expect a monitor to actively use the cameras on a daily basis. A key reason fixed cameras are generally used is that they cost 5 to 8 times less than PTZs (fixed cameras average Rs.12000 to Rs. 22000 whereas PTZ cameras can be over Rs. 75,000 INR).

2. Color vs. Infrared vs. Thermal: In TV, a video can be color or black and white. In video surveillance today, the only time producing a black and white image makes sense is when lighting is very low (e.g., night time). In those conditions, infrared or thermal cameras produce black and white images. Infrared cameras require special lamps (infrared illuminators) that produce clear image in the dark (but are significantly more expensive than color cameras - often 2x to 3x more). Thermal cameras require no lighting but product only silhouettes of objects and are very expensive (Rs. 300,000 to Rs. 1000,000 on average) In day time or lighted areas, color cameras are the obvious choice as the premium for color over black and white is trivial.

3. Standard Definition vs. Megapixel: This choice is similar to that of TVs. Just like in the consumer world, historically everyone used standard definition cameras but now users are shifting into high definition cameras. While high definition TV maxes out at 3 MP, surveillance cameras can provide up to 16 MP resolutions. In 2008, megapixel cameras only represent about 4% of total cameras sold but they are expanding very rapidly.
4. IP vs. Analog: The largest trend in video surveillance today is the move from analog cameras to IP cameras. While all surveillance cameras are digitized to view and record on computers, only IP cameras digitize the video inside the camera. While most infrared and thermal cameras are still only available as analog cameras, you can only use megapixel resolution in IP cameras. Currently, 20% of cameras sold are IP and this percentage is increasingly rapidly.

Most organizations will mix and match a number of different camera types. For instance, an organization may use infrared fixed analog cameras around a perimeter with an analog PTZ overlooking the parking lot. On the inside, they may have a fixed megapixel camera covering the warehouse and a number of fixed IP cameras covering the entrance and hallways.

2. Connectivity

In professional video surveillance, cameras are almost always connected to video management systems for the purpose of recording and managing access to video. There are two main characteristics to decide on for connectivity.
• IP vs. Analog: Video can be transmitted over your computer network (IP) or it can be sent as native analog video. Today, most video feeds are sent using analog but migration to IP transmission is rapidly occurring. Both IP cameras and analog cameras can be transmitted over IP. IP cameras can connect directly to an IP network (just like your PC). Analog cameras cannot directly connect to an IP network. However, you can install an encoder to transmit analog feeds over IP. The encoder has an input for an analog camera video feed and outputs a digital stream for transmission over an IP network.
• Wired vs. Wireless: Video can be sent over cables or though the air, whether you are using IP or analog video. Over 90% of video is sent over cables as this is generally the cheapest and most reliable way of sending video. However, wireless is an important option for transmitting video as deploying wires can be cost-prohibitive for certain applications such as parking lots, fence lines and remote buildings.

3. Video Management System
Video management systems are the hub of video surveillance solutions, accepting video from cameras, storing the video and managing distribution of video to viewers.
There are four fundamental options in video management systems. Most organizations choose one of the four. However, it's possible that companies may have multiple types when they transition between one to another.
• DVRs are purpose built computers that combine software, hardware and video storage all in one. By definition, they only accept analog camera feeds. Almost all DVRs today support remote viewing over the Internet. DVRs are very simple to install but they significantly limit your flexibility in expansion and hardware changes. DVRs are still today the most common option amongst professional buyers. However, DVRs have definitely fallen out of favor and the trend is to move to one of the three categories below.

• HDVRs or hybrid DVRs are DVRs that support IP cameras. They have all the functionality of a DVR listed above plus they add support for IP and megapixel cameras. Most DVRs can be software upgraded to become HDVRs. Such upgrades are certainly a significant trend and is attractive because of the low migration cost (supports analog and IP cameras directly).
• NVRs are like DVRs in all ways except for camera support. Whereas a DVR only supports analog cameras, an NVR only supports IP cameras. To support analog cameras with an NVR, an encoder must be used.

• IP Video Surveillance Software is a software application, like Word or Excel. Unlike DVRs or NVRs, IP video surveillance software does not come with any hardware or storage. The user must load and set up the PC/Server for the software. This provides much greater freedom and potentially lower cost than using DVR/NVR appliances. However, it comes with significant more complexity and time to set up and optimize the system. IP video surveillance software is the hottest trend in video management systems currently and is the most frequent choice for very large camera counts (hundreds or more).

4. Storage

Surveillance video is almost always stored for later retrieval and review. The average storage duration is between 30 and 90 days. However, a small percentage of organization store video for much shorter (7 days) or for much longer (some for a few years).
The two most important drivers for determining storage duration is the cost of storage and the security threats an organization faces.
While storage is always getting cheaper, video surveillance demands huge amount of storage. For comparison, Google's email service offer about 7 GB/s of free email storage. This is considered to be an enormous amount for email. However, a single camera could consume that much storage in a day. It is fairly common for video surveillance systems to require multiple TBs of storage even with only a few dozen cameras. Because storage is such a significant cost, numerous techniques exist to optimize the use of storage.
The type of security threats also impact determining storage duration. For instance, a major threat at banks is the report of fraudulent investigations. These incidents are often not reported by affected customers until 60 or 90 days after the incident. As such, banks have great need for longer term storage. By contrast, casinos usually know about issues right away and if a problem is to arise they learn about it in the same week. Casinos then, very frequently, use much shorter storage duration (a few weeks is common).
Three fundamental types of storage may be selected:
• Internal storage uses hard drives built inside of a DVR, NVR or server. Today this is still the most common form of storage. With hard drives of up to 1 TB common today, internal storage can provide total storage of 2TB to 4TB. Internal storage is the cheapest option but tends to be less reliable and scalable than the other options. Nonetheless, it is used the most frequently in video surveillance.

• Directly Attached storage is when hard drives are located outside of the DVR, NVR or server. Storage appliances such as NAS or SANs are used to manage hard drives. This usually provides greater scalability, flexibility and redundancy. However, the cost per TB is usually more than internal storage. Attached storage is most often used in large camera count applications.

• Storage Clusters are IP based 'pools' of storage specialized in storing video from large numbers of cameras. Multiple DVRs, NVRs or servers can stream video to these storage clusters. They provide efficient, flexible and scalable storage for very large camera counts. Storage clusters are the most important emerging trend in video surveillance storage.
http://arindamcctvaccesscontrol.blogspot.in/2013/10/analog-cctv-storage.html

5. Video Analytics
Video analytics scan incoming video feeds to (1) optimize storage or (2) to identify threatening/interesting events.
Storage optimization is the most commonly used application of video analytics. In its simplest form, video analytics examines video feeds to identify changes in motion. Based on the presence or absence of motion, the video management system can decide not to store video or store video at a lower frame rate or resolution. Because surveillance video captures long periods of inactivity (like hallways and staircases, buildings when they are closed, etc.), using motion analytics can reduce storage consumption by 60% - 80% relative to continuously recording.
Using video analytics to identify threatening/interesting events is the more 'exciting' form of video analytics. Indeed, generally when industry people talk of video analytics, this is their intended reference. Common examples of this are perimeter violation, abandoned object, people counting and license plate recognition. The goal of these types of video analytics is to pro-actively identify security incidents and to stop them in progress (e.g., perimeter violation spots a thief jumping your fence so that you can stop them in real time, license plate recognition identifies a vehicle belonging to a wanted criminal so you can apprehend him).
These video analytics have been generally viewed as a disappointment. While many observers believe that video analytics will improve, the video analytics market is currently contracting (in response to its issues and the recession).

6. Viewing Video
Surveillance video is ultimately viewed by human beings. Most surveillance video is never viewed. Of the video that is viewed, the most common use is for historical investigations. Some surveillance video is viewed live continuously, generally in retail (to spot shoplifters) and in public surveillance (to identify criminal threats. Most live video surveillance is done periodically in response to a 'called-in' threat or to check up on the status of a remote facility.
Four fundamental options exist for viewing video:
• Local Viewing directly from the DVR, NVR or servers is ideal for monitoring small facilities on site. This lets the video management system double as a viewing station, saving you the cost of setting up or using a PC. This approach is most common in retailers, banks and small businesses.

• Remote PC Viewing is the most common way of viewing surveillance video. In this approach, standard PCs are used to view live and recorded video. Either a proprietary application is installed on the PC or a web browser is used. Most remote PC viewing is done with an installed application as it provides the greatest functionality. However, as web applications mature, more providers are offering powerful web viewing. The advantage of watching surveillance video using a web browser is that you do not have to install nor worry about upgrading a client.

• Mobile Viewing allows security operators in the field to immediately check surveillance video. As responders and roving guards are common in security, mobile viewing has great potential. Though mobile clients have been available for at least 5 years, they have never become mainstream due to implementation challenges with PDAs/phones. Renewed interest and optimism has emerged with the introduction of the Apple iPhone.

• Video Wall Viewing is ideal for large security operation centers that have hundreds or thousands of cameras under their jurisdiction. Video walls provide very large screens so that a group of people can simultaneously watch. This is especially critical when dealing with emergencies. Video walls generally have abilities to switch between feeds and to automatically display feeds from locations where alarms have been triggered.

7. Integrating Video with Other Systems
Many organizations use surveillance video by itself, simply pulling up the video management systems' client application to watch applications. However, for larger organizations and those with more significant security concerns, this is an inefficient and poor manner to perform security operations. Instead, these organizations prefer an approach similar to the military's common operational picture (COP) where numerous security systems all display on a singular interface.
Three ways exist to deliver such integration with video surveillance:

• Access Control as Hub: Most organizations have electronic/IP access control systems. These systems have been designed for many years to integrate with other security systems such as intrusion detection and video surveillance. This is the most way to integrate video surveillance and relatively inexpensive ($10,000 - $50,000 USD). However, access control systems are often limited in the number and depth of integration they support.

• PSIM as Hub: In the last few years, manufacturers now provide specialized applications whose sole purpose are to aggregate information from security systems (like video surveillance) and provide the most relevant information and optimal response policies. These applications tend to be far more expensive (($100,000 - $1,000,000 USD) yet support a far wider range of security manufacturers and offer more sophisticated features.

• Video Management System as Hub: Increasingly, video management systems are adding in support for other security systems and security management features. If you only need limited integration, your existing video management system may provide an inexpensive (yet limited) solution.

8.Video Resolutions

1.Analog Video Resolutions
Video surveillance solutions use a set of standard resolutions. National Television System Committee (NTSC) and Phase Alternating Line (PAL) are the two prevalent analog video standards. PAL is used mostly in Europe, China, and Australia and specifies 625 lines per-frame with a 50-Hz refresh rate. NTSC is used mostly in the United States, Canada, and portions of South America and specifies 525 lines per-frame with a 59.94-Hz refresh rate.
These video standards are displayed in interlaced mode, which means that only half of the lines are refreshed in each cycle. Therefore, the refresh rate of PAL translates into 25 complete frames per second and NTSC translates into 30 (29.97) frames per second..

Table of Analog Video Resolutions (in pixels)
Format	NTSC-Based (in pixels)	PAL-Based (in pixels)
QCIF	176 × 120	176 × 144
CIF	352 × 240	352 × 288
2CIF	704 x 240	704 x 288
4CIF	704 × 480	704 × 576
D1	720 × 480	720 × 576

Note that the linear dimensions of 4CIF are twice as big as CIF. As a result, the screen area for 4CIF is four times that of CIF with higher bandwidth and storage requirements. The 4CIF and D1 resolutions are almost identical and sometimes the terms are used interchangeably.

2.Digital Video Resolutions

User expectations for resolution of video surveillance feeds are increasing partially due to the introduction and adoption of high-definition television (HDTV) for broadcast television. A 4CIF resolution, which is commonly deployed in video surveillance, is a 4/10th megapixel resolution. The HDTV formats are megapixel or higher. Table lists the typical resolutions available in the industry.

Size/ Format	Pixels
QQVGA	160x120
QVGA	320x240
VGA	640x480
HDTV	1280x720
1M	1280x960
1M	1280x1024
2M	1600x1200
HDTV	1920x1080
3M	2048x1536

While image quality is influenced by the resolution configured on the camera, the quality of the lens, sharpness of focus, and lighting conditions also come into play. For example, harshly lighted areas may not offer a well-defined image, even if the resolution is very high. Bright areas may be washed out and shadows may offer little detail. Cameras that offer wide dynamic range processing, an algorithm that samples the image several times with differing exposure settings and provides more detail to the very bright and dark areas, can offer a more detailed image.

As a best practice, do not assume the camera resolution is everything in regards to image quality. For a camera to operate in a day-night environment, (the absence of light is zero lux), the night mode must be sensitive to the infrared spectrum. It is highly recommended to conduct tests or pilot installations before buying large quantities of any model of camera.

Importance of CCTV

The full form of CCTV is Closed Circuit Television Cameras. These cameras can be fitted just about anywhere with the help of a simple process. Once set up, they help to record all the activities that are taking place in a specific area unless switched off or disabled. They are quite compact in size and are not really instantly visible to everyone. CCTV’s vary greatly in terms of the picture and sound quality that they can provide to their users. They may be colored or black and white. Some of them may show very clear pictures while others may showcase slightly hazy or disturbed videos. Thus, it is vital to choose carefully while buying CCTV cameras. CCTV cameras come with the following benefits and their importance cannot be undermined.

1.CCTV cameras are very useful in combating terrorism. This is because it is simply not practically possible to deploy police forces in every conceivable public area to look out for strange behavior from people or the placement of strange, unclaimed objects. CCTV cameras can look out for such things and prevent acts of terrorism before they have a chance to take place. The images captured on these cameras are transmitted to a central location where they are observed by the concerned person.

2.CCTV cameras are of unprecedented importance in the field of sporting. Some of them come equipped with high technology that helps to make crucial and difficult decisions in a game or match. Every single moment of play is recorded to be used later on too for making improvements.

3.CCTV cameras, if installed in a house or building, can help combat burglaries and thefts to a large extent. Just the knowledge about the existence of such cameras is enough to deter the possible intruders who may try to do away with your things at an available opportunity. CCTV’s can record footage and send it to another system over the internet. This can be done live or later on after the day has passed. So, it can help prevent burglaries and locate criminals whose faces may have been captured.

4.CCTV cameras are of great importance in places of work. They help establish a means of control and a system of keeping checks on the employees. If the employees are found to be wanting in a certain area, the requisite steps to correct this are taken by the management.

5.CCTV cameras in public places discourage vandalism and destruction of public property as the people involved in doing so know that they are being observed. Merely the existence of these cameras greatly improves the law and order situation of a city.

6.These cameras help keep a check on your babysitter’s method of working in case you have children and are worried about leaving them all alone with a stranger. You can be assured that your child is in safe hands and make changes if you find the nanny hired by you as incompetent in any way.

Uses of CCTV in India?

* CCTV provides a deterrent to crime and vandalism.

* CCTV system enables 24 hour monitoring of all the designated areas.

* CCTV security cameras enables in clear identification of miscreants within the range of the CCTV cameras.

* To provide continuous recording of all CCTV cameras in the system.

* To enable rapid movement of any CCTV camera to pre-set positions of pan, tilt and zoom.

* To provide independent viewing of any CCTV camera at the controlling station.

* To enable live, real time recording of selected CCTV cameras.

* CCTV systems can be used to remotely or locally monitor following areas- Finance and banking, Parking areas, Educational Institutions, Jewellery showrooms, Storage godowns and warehouses, Construction sites, Gas stations, Commercial buildings, Hospitals, Shopping complexes and malls, Manufacturing plants, Transporting companies.

CCTV system should be used at offices, factories, restaurants, shops, workshops, schools, colleges, hospitals, airports, banks, malls, industrial and comercial spaces.

Electronic Access Control Systems: A Global Strategic Business Report

Global Electronic Access Control Systems Market to Reach US$6.0 Billion by 2015, According to New Report by Global Industry Analysts, Inc.

GIA announces the release of a comprehensive global report on Electronic Access Control Systems. Although the prolonged severity of the recent economic slowdown, and depressed key end-use sectors have elicited decline in value sales for electronic access control systems (EACS), the market is nevertheless expected to recover poise in the short to medium term period to reach US$6.0 billion by 2015. Primary factors fingered to drive this growth include increasing concerns over safety and security among individuals and organizations, post recession resurgence in key end-use markets and technology developments. Robust growth in demand from developing markets, particularly Asia-Pacific also augurs well for the market.
By product, Card-Based Electronic Access control systems market continues to be the largest product segment, holding a lion’s share of the global market. Smart cards represent the largest revenue contributor to the card-based EACS market. Audio and Video-Based Electronic Access Control Systems market is the fastest growing product segment, waxing at a CAGR of about 6.8% over the analysis period Major players in the marketplace include Aiphone Co. Ltd., ASSA ABLOY AB, BIO-key, International Inc., DigitalPersona Inc, Gunnebo Ab, Hirsch Electronics Corporation, Honeywell Access Systems, Ingersoll Rand Recognition Systems Inc., Linear LLC, Imprivata® Inc., Kaba Holding AG, L-1 Identity Solutions, NAPCO Security Systems Inc., PAC International Ltd, SAFRAN Group, SecuGen Corporation, Siemens Industry USA Building Technologies, The Chamberlain Group Inc, UTC Fire & Security, Chubb Securite S.A.S, and GE Security Inc.

http://www.gobeyondsecurity.com/forum/topics/electronic-access-control

What is the difference between "biometric identification" and "biometric verification"?

What is the difference between "biometric identification" and "biometric verification"?

Biometrics are used for different purposes, but they are generally part of either a verification system or an identification system. The differences between these two types of systems can make a difference in how quickly the system operates and how accurate it is as the size of a biometric database increases.

Verification Systems
Verification systems seek to answer the question “Is this person who they say they are?” Under a verification system, an individual presents himself or herself as a specific person. The system checks his or her biometric against a biometric profile that already exists in the database linked to that person’s file in order to find a match.
Verification systems are generally described as a 1-to-1 matching system because the system tries to match the biometric presented by the individual against a specific biometric already on file.
Because verification systems only need to compare the presented biometric to a biometric reference stored in the system, they can generate results more quickly and are more accurate than identification systems, even when the size of the database increases.

Identification Systems
Identification systems are different from verification systems because an identification system seeks to identify an unknown person, or unknown biometric. The system tries to answer the questions “Who is this person?” or “Who generated this biometric?” and must check the biometric presented against all others already in the database. Identification systems are described as a 1-to-n matching system, where n is the total number of biometrics in the database. Forensic databases, where a government tries to identify a latent print or DNA discarded at a crime scene, often operate as identification systems.


one-to-one comparison, biometric verification systems are generally much faster than biometric identification systems. Most commercial applications of biometrics for time and attendance or access control use biometric verification.

How to Selecting a Video Cable

Selecting Video Cable

There are two factors that govern the selection of cable: the location of cable runs, either indoor or outdoor, and the maximum length of the individual cable runs.

Video coaxial cable is designed to transmit maximum signaling energy from a 75 ohm source to a 75 ohm load with minimum signal loss. Excessive signal loss and reflection occurs if cable rated for other than 75 ohms is used. Cable characteristics are determined by a number of factors (core material, dielectric material and shield construction, among others) and must be carefully matched to the specific application. Moreover, the transmission characteristics of the cable will be influenced by the physical environment through which the cable is run and the method of installation.

Use only high quality cable and be careful to match the cable to the environment (indoor or outdoor). Solid core, bare-copper conductor is best suited to video applications, except where flexing occurs. In locations where the cable must be continuously flexed (i.e., when used with scanners or pan & tilts), use cable intended for such movement. This cable will have a stranded wire core. Use only cable with pure copper stranding. Do not use cable with copper-plated steel stranding because it does not transmit effectively in the frequency range used in CCTV.

The preferred dielectric material is foam polyethylene. Foam polyethylene has better electrical characteristics and offers the best performance over solid polyethylene, but it is more vulnerable to moisture. Use cable with solid polyethylene dielectric in applications subject to moisture.

In the average CCTV installation, with cable lengths of less than 750 feet (228 m),RG59/U cable is a good choice. Having an outside dimension of approximately 0.25 inches, it comes in 500-and 1,000-foot rolls.

For short cable runs, use RG59/U with a 22-gauge center conductor, which has a DC resistance of about 16 ohms per 1,000 feet (304 m). For longer runs, the 20-gauge variety which has a DC resistance of approximately 10 ohms per 1,000 feet will work well. In either case, cables with polyurethane or polyethylene as the dielectric material are readily available.

For installations requiring cable runs between 800 (244 m) and 1,500 feet (457 m),RG6/U is best. Having the same electrical characteristics as RG59/U, its outer dimension also is about equal to that of RG59/U.RG6/U comes in 500-,1000-and 2000-foot rolls, and it may be obtained in a variety of dielectric and outer-jacket materials. Due to its large-diameter center conductor of about 18 gauge,RG6/ U has a DC resistance of approximately 8 ohms per 1,000 feet (304 m) and can deliver a signal farther than RG59/U.

Use RG11/U to exceed the capability of RG6/U. Once again, the electrical characteristics of this cable are basically the same as the others. The center conductor can be ordered in 14-or 18-gauge sizes, producing a DC resistance of approximately 3-8 ohms per 1,000 feet (340 m). Being the largest of the three cables at 0.405 inches, it is more difficult to handle and install.RG11/U cable usually is delivered in 500-,1000-and 2000-foot rolls.

Because of special applications, variations of RG59/U, RG6/U and RG11/U frequently are introduced by manufacturers.

Due to changes in fire and safety regulations throughout the country, Teflon and other fire-retardant materials are becoming more popular as outer-jacket and dielectric materials. In case of a fire, these materials do not give off the same poisonous fumes as PVC-type cables, and therefore, are considered safer.

For underground applications, direct burial cables, made specifically for that purpose are recommended. The outer jacket of this type of cable contains moisture-resisting and other materials that protect the cable, allowing it to be placed directly into a trench.

With numerous choices available, finding the right video cable for each camera application should be easy. After the installation has been properly assessed, read the equipment specifications and complete the appropriate calculations.

Cable Runs

coax cable has built-in losses, the longer and smaller the cable is, the more severe the losses become; and the higher the signal frequency, the more pronounced the losses. Unfortunately this is one of the most common and unnecessary problems currently plaguing CCTV security systems as a whole.

If, for example, your monitor is located 1,000 feet (304 m) from the camera, approximately 37-percent(37%) of the high frequency information will be lost in transmission. The unfortunate aspect of this condition is that it is not obvious. You cannot see information that is not there and may not even realize that information has been deleted. Because many CCTV security systems have cable runs that exceed several thousand feet, unless you are aware of this characteristic of cable, your system may be providing a seriously degraded image.

So, if your cameras and monitors are separated by lengths greater than 750 feet (228 m), you should check to make certain that some provision has been made to guarantee the video signal's transmission strength.

Cable Type* RG59/U = 750 ft.

Cable Type* RG6/U = 1,000 ft.

Cable Type* RG11/U = 1,500 ft.

* = Minimum cable requirements= 75 ohms impedance, All-copper center conductor, All-copper braided shield with 95% braid coverage.

Cable Termination

In video security systems, camera signals must travel from the camera to the monitor. The method of transmission is usually "coax" cable. Proper termination of cables is essential to a system's reliable performance.

Because the characteristic impedance of coax cable ranges from 72 to 75 ohms, it is necessary that the signal travels on a uniform path along any point in the system to prevent any picture distortion and to help ensure proper transfer of the signal from the camera to the monitor. The impedance of the cable must remain constant with a value of 75 ohms. To properly transfer power between two video devices with acceptable losses, the signal output from the camera must match the input impedance of the cable, which in turn must match the input impedance of the monitor. The end point of any video cable run must be terminated in 75 ohms. Usually, the cable run will end at the monitor, which will ensure that this requirement is met.

Usually the video input impedance of the monitor is controlled by a switch located near the looping video (input/output) connectors. This switch allows for either 75 ohm termination if the monitor is the "end point",or Hi-Z for looping to a second monitor. Check equipment specifications and instructions to determine the proper termination requirements. Failure to terminate signals properly usually results in a high contrast, slightly grainy picture. Ghosting and other signal imperfections also may be evident.

It important to note that the BNC connectors , which are usually used for terminating coax cable, are manufactured in two different impedance -75 ohm for video use and 50 ohm for radio use. Most shopkeepers are not a ware of this difference so it is better to check the manufacturer's specification before you buy.

Unsaddled twisted pair (UTP)

UTP cabling is both in expensive and ideal for transmission of video signal up to 1350m. the cabling is run to multiplexer that supports the popular RJ45 connector . Legacy cameras with coax connectors can be retrofit with balun (balanced/unbalanced ) adpters allowing the signal to be converted from the coaxial cable (unbalanced ) to twisted pair (balanced) cable. A typical system consists of a transmitter connected to a coax cable or connector which is then converted to a signal suitable for transmitting over twisted pair cable. On the receiving end of the twisted-pair cable is a receiver that converts the signal back to one suitable for transmission on coax cable.

UTP. Requires only one twisted pair cable to carry power, video and control signals , as opposed to three different proprietary cables with traditional CCTV systems.

While the total cost of UTP cabling can be up to 30% less than traditional CCTV systems over the life of the system, it easily accommodates technological advances such as digital integration IP-based networks and power over Ethernet.

Optical fibre is some times used in this environment where distances would require use of repeaters for signal strength or where EMI. (Elector-Magnetic interference) is an issue.

Fibre Optic Cable

While coaxial cable is the most suitable cable for CCTV signal transmission over short distances it is best to consider other mediums for distances greater than 1 kilometer. The most suitable for these distances is fibre optic.

Fibre optic is a fine strand of glass which is highly transparent. There are two main types referred to single mode and multi-optic fibres. The single mode fibre optic has a high level of efficiency but can transmitting only one mode. Laser transmitters an receivers arousal required for single mode application . Multi -mode fibre optics is thicker and can operate in several modes and can accommodate cheaper forms of transmission media such as infrared . These cables are used main lyover shorter distances while the single mode fibre would be used where distance and performance were critical . The main types of applications for fibre optics are:-

Light Guide fiber-used in instrument panels and lamps it carries visible light only.

Coherent fibre-Normally referred to as coherent bundle because of its construction. This glass fibre will carry an undischarged image of light over a short distance. Its ideal for extending the lens with application in covert surveillance. High performance-For CCTV application we tend to use high performance fibers with a signal transmission media. For CCTV application we have to use the latter , high performance fibers. The glass stransparency quality of the glass is a key factor in its ability to transmit light effectively over distances and this is being improved constantly.

Fiber optic system may consist of a standard camera with the video signal being fed into a fibre optic trasmitter. The transmitter consists of circuits to convert the video signal into a series of modulated pulses . These pulses are then fed to the light source that may either be a laser or light emitting diode (LED) which emits a series of light pulses .these light pulses are focused on to the centre core of the cable which acts as a guide to the light passing along the fibre's lenght. The main light passes straight along the centre of the fibre while a little of the light hits the side of the glass tube. This is reflected back into the centre by the cladding.

This results in very low transmission losses over long distances. Fibre optic cable also has the advantage of not being affected by electromagnetic interference or EMI.

Splitting / Amplifying the Video Signal

Video signal used in CCTV equipment is nominally a one volt peak-to-peak signal and is impedance sensitive to 75 ohms for ideal video reproduction at the monitor. If these parameters are not kept, then the video will degrade.

Distribution Amplification

If the installation of a system requires viewing the video at multiple locations from a single camera, there are a few different ways of accomplishing this. One way is through using a distribution amplifier. This device basically takes the single video signal and reproduces the exact signal into multiple outputs; and in the case of the Pelco DA104DT you would get four identical outputs.

So, if the input signal is a one volt peak-to-peak signal you will get four output signals of the same amplitude. Providing the run distance for the type of coax used is kept within the specified length, no other equipment will be needed to reproduce a nice clear video display on each monitor. Another timesaving feature of the Pelco DA104DT is that there are not adjustments required. Just connect the unit, turn it on, and the installation is complete. If the need arises where more than four signals are required, multiple units can be linked together by simply using one of the output signals as an input signal to the next unit, and so on.

Equalizing Amplification

Due to the many factors that can effect the video signal, it is sometimes necessary to enhance the video signal (as in transmitting a nominal video signal level) directly out of the camera, through RG59 coax to a monitor, while still producing a clear video display across the entire length of the coax. In this case the coax should not exceed 750 feet (228 m).

However, let's say you need to use RG59 because it's more flexible and much easier to work with but the cable length must be 1,500 feet (457 m). The signal at this point is going to be weak and will display a very degraded picture on the monitor. As mentioned, there are many things that can effect signal strength before the signal reaches the monitor. If you find a weak signal, simply pass the weak signal through an equalizing amplifier, make the required adjustments, and once again there will be a good, strong signal that will produce a nice picture.

The Pelco model EA2010 is a post-equalizing amplifier which simply means that this device will be located close to the monitor. There's an advantage to this design in that AC power is usually more readily available at the monitoring location than it is somewhere back up the coax line, and with this type of design it only requires one person to view the monitor display while at the same time making the required adjustments to obtain the nominal signal level.

As mentioned in the example on RG59,the signal strength is good up to nominally 750 feet (228 m). With the Pelco EA2010 amplifying the signal, the same grade of coax can be used in runs of up to 3,000 feet (914 m).

In regard to any equalizing amplification system, there is another type of post-equalizing amplifier that Pelco offers. It is the half-duplex post-equalizing amplifier. This device (as far as the amplification of the video signal is concerned) is exactly like the EA2010.The difference is that the EA2000 was designed specifically for use with any of the Pelco Coaxitron® (up-the-coax) control/transmitter systems. This device enables the video signal requiring amplification to be transmitted over the same coaxial cable over which the control signal is transmitted, whereas if you used the EA2010 it would block the Coaxitron® control signal from being transmitted.

Cabling for IP Cameras

IP convergence means attaching different building and communication systems -- such as data, voice, security cameras and building automation systems -- onto a common network through a common Internet protocol. In the surveillance world, IP convergence means moving from analog to IP cameras.

IP camera technology offers new and expanded features in CCTV surveillance that were previously unavailable on analog cameras. However, performance and scalability can be affected because of poor system infrastructure, as well as product performance.

For organizations to realize the full benefits of IP video surveillance, they must design and build a system that is capable of meeting current and future requirements, which includes allocating sufficient bandwidth to video-carrying traffic that will not congest the network. To do this, they must implement a standards-based structured cabling system that will allow future devices to be added, which will save time and money by providing the biggest return on investment.

Cable selection and bandwidth go hand-in-hand. Considerations when selecting the cable media include number of cameras, type of camera, location of the cameras (environment), distance to the telecom rooms, type of termination equipment and whether PoE will be running through the cable or local power will be provided at the device end. Another factor when selecting cable is the length of time planned to occupy the building.

Today’s TIA standards define cabling types, distances, connectors, cable system architectures, cable performance characteristics, pathways, cable installation requirements and methods of testing installed cable to help system designers and installers select the most efficient cabling for each environment. TIA-recognized structured cabling standards recommend twisted pair copper and fiber-optic cable as the preferred media selection for efficient IP network systems. However, security integrators need to be aware of the range of options available and the pros and cons of each.

Coax Cable

Distances using coax cable can be up to 3,000 feet. This cable is most often found when end users would like to use their installed cable plant, which was installed for analog cameras. However, because an IP camera is equipped with an RJ-45 connection, media converters are needed on each end of the coax cable runs.

Using existing coax cable for running Ethernet to IP cameras is a “band-aid” approach and does not comply with TIA. This is a fast solution, but eventually the cabling system will need to change to a structured cabling system -- through twisted pair or fiber -- especially when higher bandwidth megapixel cameras are required. Running Ethernet over coax is limited to less than 1 GB transmissions. Therefore, as the bandwidth increases on both the camera and the traffic running through the network, coax cable capabilities will be limited.

Twisted Pair

Unshielded or shielded twisted pair cable provides many benefits over coax. Twisted pair, with its RJ connection, allows immediate attachment to the camera. One of the biggest benefits is that twisted pair can provide power over the same cable, eliminating local power at the device end.

There are basically two grades of UTP cable: Cat-5e (100 MHz) and Cat-6 (250 MHz). A Cat-5e cable may be sufficient with its allowable 1 GB/s data rate (depending on the protocol), but Cat-6 operates at a higher data rate (up to 10 GB/s). Because of its improved transmission performance and superior immunity from external noise, systems operating over Cat-6 cabling will have fewer errors than Cat-5e. And, when inducing noise or heat -- such as in PoE and PoE Plus -- Cat-6 has been proven to operate with no latency or fear of dropped packets.

Standards-based twisted pair cabling is limited to 100 meters between the device and the termination point, such as a consolidation point or telecommunications room. The chart on the following page provides cable options for selecting cable based on distance and power. Twisted pair can actually provide a signal farther than 100 meters through active equipment, but this would not meet the TIA standards and therefore would not work if the analog camera is to be replaced with an IP camera.

Fiber-optic Cable

The answer to the distance challenge is fiber-optic cable. Fiber-optic cable can easily operate IP cameras through media conversion, allowing twisted pair patch cords or horizontal UTP cable runs to connect directly to the device and to the terminating equipment in the TR. Even coax-based analog cameras can use fiber-optic cable, but this entails deploying multiplexers in addition to media converters, which can become costly per channel.

Fiber-optic cable’s other advantages include its small diameter and biggest bandwidth carrying capacity. Fiber-optic cable is immune to electrical interference, which makes it ideal for harsh environments such as lightning, power plants and industrial manufacturing. In addition, fiber optic is a more secure signal -- because it is harder to tap into.

Since power cannot run through glass, fiber-optic cable cannot directly carry PoE. But it can be jacketed with copper conductors in the form of a composite cable. Certain cables on the market provide Ethernet to be carried through fiber strands while power runs through stranded copper conductors. Distances up to 3,850 feet can be achieved. Because the cable carries lowvoltage power -- up to 25 watts as defined by PoE Plus and IEEE 802.3at -- this cable is actually defined as a Class 3 copper cable with fiber. The total distance is limited by the media power provided through the active media converter on the termination side, as well as the gauge of the copper. The more power needed, the thicker the gauge.

Challenging Decisions and Changing Standards

Security camera locations vary depending on each installation. When the TIA standards were written, the devices in work areas consisted of telephones, modems, data terminals, fax machines and desktop computers. Although the TIA standards originally applied to data and voice Ethernet applications, mainly in office environments, they were written to be modular, providing scalability for adding IP devices. However, electronic safety and security devices, particularly surveillance equipment, create unique challenges, mainly due to environmental factors.

The BICSI organization, together with ANSI, is currently reviewing the existing standards and has created a standards group to focus solely on physical infrastructure for ESS devices. To be designated “ANSI/BICSI 005” upon completion, this standard will define cabling design and installation requirements, as well as provide recommendations specific to ESS systems, including surveillance, access control, paging, signage, and even fire detection and alarm systems.

The standard also will provide information for access control, intrusion detection and surveillance systems, as well as guidance on other topics, such as meeting the IP needs of fire detection and alarm systems. And as more and more devices find their way to the network, the selection of cabling and physical infrastructure becomes more critical.

Now we are discussed about coaxial cable's Construction

RG59/U, RG6/U and RG11/U is circular. Each has a center conductor surrounded by dielectric insulating material, which in turn is covered by a braid to shield against electromagnetic interference. The outer covering is the jacket.

The coaxial cable's two conductors are separated by a nonconductive or dielectric material. The outer conductor (braid) acts as a shield and helps isolate the center conductor from spurious electromagnetic interference. The outer covering helps physically protect the conductors.

Center Conductor:

For CCTV applications, solid copper conductors are required, which is carrying a video signal. Center conductor comes in varying diameters usually ranging from 14 gauge to 22 gauge. The structure of the center conductor generally is solid copper or copper-clad steel, designated as bare copper weld or BCW. For CCTV applications, solid copper conductors are required. Copper clad, copper weld, or BCW cables have much greater loop resistance at baseband video frequencies and should never be used for CCTV. To determine the type, look at the cut end of the center conductor. Copper clad cable will be silver in the center intead of copper all the way through. Variation in the size of the center conductor has an overall effect on the amount of DC resistance offered by cable. Cables which contain large diameter center conductors have lower resistances than cables with smaller diameters. This decreased resistance of large diameter cable enhances the ability of a cable to carry a video signal over a longer distance with better clarity, but is also more expensive and harder to work with.

For applications where the cable may move up/down or side-to-side, select cable that has a center conductor consisting of many small strands of wire. As the cable moves, these strands flex and resist wear due to fatigue better than a cable with a solid center conductor.

Dielectric Insulating Material

Center conductor is an evenly made dielectric insulating material which is available in some form of either polyurethane or polyethylene. This dielectric insulator helps determine the operating characteristics of coax cable by maintaining uniform spacing between the center conductor and its outer elements over the entire length of the cable. Dielectrics made of cellular polyurethane or foam are less likely to weaken a video signal than those made with solid polyethylene. This lower attenuation is desirable when calculating the loss/length factor of any cable. Foam also gives a cable greater flexibility, which may make an installer's job easier. Although foam dielectric material offers the best performance, it can absorb moisture, which will change its electrical behavior.

Because of its rigid properties, solid polyethylene maintains its shape better than foam and withstands the pressures of accidental pinching or crimping, but, this characteristic also makes it slightly more difficult to handle during installation. In addition, its loss/length attenuation factor is not quite as good as foam, which should be considered in long cable runs.

Braid or Shield

Cables using aluminum foil shielding or foil wrap material are not suitable for CCTV installations. Wrapped around the outside of the dielectric material is a woven copper braid (shield), which acts as a second conductor or ground connection between the camera and the monitor. It also acts as a shield against unwanted external signals commonly called electromagnetic interference or EMI, which may adversely affect a video signal.

The amount of copper or wire strands in the braid deter- mine how much EMI it keeps out. Commercial grade coax cables containing loosely woven copper braid have shielding coverages of approximately 80%. These cables are suitable for general purpose use in applications where electrical interference is known to be low. They also work well when the cable is to be installed in metal conduit or pipe, which also aids in shielding.

If you are not sure of the conditions and are not running pipe to screen out more EMI, use a cable with a "maximum shield" or heavy braid--type cable containing more copper than those of commercial grade coax. This extra copper obtains the higher shielding coverage by having more braid material made in a tighter weave. For CCTV applications, copper conductors are needed.

Cables using aluminum foil shielding or foil wrap material are not suitable for CCTV work. Instead, they usually are intended to transmit radio frequency signals such as those employed in transmitter systems or in master antenna distribution systems.

Aluminum or foil cable may distort a video signal to such a point that signal quality may be far below the level required for proper system operation, especially over long cable runs, and therefore not recommended for CCTV use.

Outer Jacket

The last component comprising a coax cable is the outer jacket. Although other materials are used, polyvinyl chloride, or PVC, is commonly used in its construction. Available in many colors such as black, white, tan, and gray, the jacket lends itself to both indoor and outdoor applications.

Newly developed some Video & Power Combination Cable is there in market.

This combination cable featuring BNC to BNC video connectors and 2.1mm DIN male & female for power supply connection. A BNC to RCA adapter is also included. Also included are two pigtails to allow breakout of power connectors to use with screw terminal power supplies and cameras. This cable is available in 50 foot and 100 foot lengths. Maximum distance for DC power should not exceed 100 feet.

Specials thanks to all of Manufacturers, Suppliers & Exporters to provide the information.