Video over IP
From Here to Eternity
Youv'e Been Framed
Design Considerations for Public Area Surveillance
NOTE: The information contained in the articles was correct at the time of publication, but may in some cases now be out of date
This article is based on a presentation to the Securex 2001 conference, organised by CMP, 630 Chiswick High Road, London W4 5BG. Tel 020 8987 7877.
Published by the Builder Group in Security Installer magazine (December 2001).
WHAT IS DIGITAL RECORDING? It is the video equivalent of going from vinyl records to CD audio. But why use digital recording anyway? For three reasons: labour, labour and labour. It is all about handling and storage and how much time is involved – if it takes 45 seconds to change a tape, that could add up to a couple of hundred hours per year in some CCTV schemes.
What medium does digital recording use for storage? There are a variety of media: hard disk, removable hard disk, RAID (redundant array of inexpensive disks), DVHS, DV (digital video), DAT (digital audio tape), Exabyte, AIT (advanced intelligent tape), CD-ROM or WORM (write once read many), DVD (digital versatile disk) or PD (photo-optic disk).
How much can they store?
* HD up to 60GB
* Removable HD are usually a little smaller
* RAID up to 16TB
* DAT up to 12GB and stackable usually to 5 (No 6 is a cleaner)
* EXABYTE up to 14GB, stackable to 12TB.
(EXABYTE in capital letters is the name of a manufacturer of a tape-based storage device. In lower case, exabyte means 2 to the power of 60.)
* AIT 2 up to 50GB and stackable to 32TB, includes embedded memory (16k)
* DV up to 60GB
* CD ROM up to 700MB
* DVD up to 4.7GB.
They are not compatible, except you can play CDs on a DVD machine, but not the other way round.
Dilemma: When evidence is seized by the police, how much other material do they take? Do they have a right to that other material – does it take a court order? Will the police replace the media they took? Not very likely.
How long will a recording last?
It depends on the data compression used. A quick calculation for the equivalent of an E180 tape: 50 fields per second for three hours equals 540,000 images. Compress to, say, 20kB per image would mean the disk needed is 10.8GB.
Common compression types include JPEG, JPEG 2000 (a superseding version, not compatible with JPEG), MPEG 1 and MPEG 2, wavelet and H261 and H263. Too much compression can ruin the image, but some compression types give fixed quality. Smaller pictures mean smaller files – but a smaller picture also means less detail. CIF (Common Intermediate Format) is only 352 pixels by 288 high.
Can I play my recording in court?
It is unlikely – though possible, if you take your own equipment – because there is no compatibility … yet. But there is hope for the future in the form of a group called the Digital Forum.
It is a myth that predictive compression (MPEG) is not accepted in court. All compression techniques are permissible – unless the judge rules them out.
* What does the customer/installer need?
* A real time video output
* The ability to make prints
* The ability to export to something like CD.
How does the customer know which to buy?
There are a couple of questions to ask first:
* What do you need from the recordings?
* How long will you keep them? The recommendation is 31 days.
* What will you do with your old multiplexer
and VCR? – Don’t throw them out.
* How will you make evidential copies?
A final warning: the technology may be out of date in six to nine months – but think of the benefits!
The article following was published in CCTVision the official publication of the CCTV User Group
and is now reproduced with their kind permission.
5 Earsham Street
Suffolk NR35 1AE
Tel 01986 896937
FROM HERE TO ETERNITY
An interesting title perhaps, but it is often what we expect of our poor coaxial cable.
In modern town centres we have now far exceeded the maximum cable run for realistic cables and as a result we have graduated to the "black art" of optical fibres for our transmission in town for links of 200m to over 15km. The telecommunications providers charge what appear to be high rates, but justify it by saying, "we are losing telephony revenue by giving fibres to CCTV". This causes some Authorities to explore alternative means of transmission of the signals to the control room.
Microwave, radio, GSM, PSTN, ISDN, LASER, Ethernet, ATM Internet and HDSL are all media that can be used for the transmission of CCTV pictures. Not all of these will give us full frame rate of video (50 fields per second) and therefore need to be chosen for the appropriate application. There are also pro's and con's to each, which I will try to briefly cover.
Probably the most commonly used alternative medium is microwave. The equipment is well proven and generally reliable. In some circumstances, such as Watford, town centre TV systems are all transmitted on microwave to the control room. In this case on important factor is frequency management. With many signals coming into the same receiving point there is the potential for cross talk between signals. It is therefore important for the individual links to be chosen for the frequency and the directions of transmission to minimise the possibility of interference. This is best achieved by the Tenderers for any particular system, involving the microwave manufacturer at the survey stage and getting a transmission plan drawn up. This must include the possible future expansion of the cameras "we cant afford this year but will add next year (or whenever)." If the potential expansion is not included in the original plan, then it is likely that when the expansion is carried out that it may not be possible to integrate the new links without complications of interference with existing signals.
A problem often overlooked when microwave is used over tidal water is reflected signal paths. Water reflects microwave, therefore a link will often have both a direct signal and a reflected signal. In a static situation this is not a problem, but where the tide rises and falls the reflected path changes and causes interference with the received signal.
Problems with microwave also include things such as; it is a "line of sight" transmission, it is a narrow angle of beam and therefore needs firm fixings. It is important to also remember that physical obstructions can interrupt the beam, these include birds. Where do birds roost? On top of buildings. Where do we locate microwave dishes? On top of buildings!! What will you do when they construct a high rise building in the path of your link? All you can do is get permission to put a receiver and transmitter on their roof to relay the signal over the new obstruction
Another medium becoming popular is radio, because of the proliferation of mobile systems. This is at the high UHF or low microwave bands of 1394MHz or 2.4 and 2.8GHz, of which a number of manufacturers are Radio Communications Agency (RCA) licence exempt, within certain criteria of range or power limiting. Many of the issues highlighted above for microwave also apply to radio transmissions. This can include items such as reflected signal path, which will not be tidal but vehicle movement, and also line of sight transmission, but we have the added complication that the link may only operate over 20 metres in a town centre because the antenna is at low level. "High gain antenna available", but if it is installed on the transmitter, does this now exceed the Effective Radiated Power (ERP) and contravene the exemption of the licence?
The fanfare that accompanied the start of use of GSM as a transmission medium has come to little at this stage. The maximum data rates at the moment over GSM are limited to 19.2k bits per second, ie slower than a dial up telephone link on PSTN. Hold your breath until the next generation of GSM, which will, supposedly, have data transmission rates of up to 2Mbits per second. This will give picture update rates of 100 times that of the current links (15 times as fast as ISDN 2e). When this does happen, watch what happens to the possibly more costly fibre link prices, we may have systems that dial up each camera to access the pictures rather than having 32 continuous images all the time in the control room. There are rumours of further developments in telecommunications that will possibly supercede GSM and give even better results.
Or in American speak POTS (Plain Old Telephone System). The telephone system we all know and love, that with the right equipment and a couple of modems, we can send signals to the other end of the country, or even the world, for the cost of a phone call. The disadvantage is that the data pipe this gives us is not very big, just 38.4kbps effectively (56kbps modems only work at 56kbps in one direction). This means that with the data compression we can expect picture updates every seven to 20 seconds depending upon the resolution. In simple terms this means the higher the resolution, the slower the update rate.
The newer digital telephone system that enables much faster data transmission rates of 128kbps dial-up (192kbps leased line), that is 3 times the speed. Thus the update rate is faster......not always... because when signals are sent as PSTN we sometimes only send the changes, but with many of the ISDN systems the whole picture is sent every time, which means more data and more data takes longer. The ISDN system is not in place all over the world, but it is "e" European harmonised, so it can be used through Europe (where installed) without compatibility problems. The USA is starting to install ISDN, but most of their digital telephony is on Switch 56, which is not compatible with ISDN.
Not the Star Wars weapon, but a low power, often Infra-Red, light source onto which the video signal is modulated. No licence is required and , according to the spec sheets, will work up to 1km. Sounds good doesn't it. However beware there are some considerations to bear in mind. We have a beam diameter of about 2 milli-radians (or 0.1 degrees) which, in practical terms, is a beam diameter of 2m at a range of 1km. Because we are using light, any physical obstruction may cause the beam to be broken and the signal to be lost, so birds, fog, heavy rain and vehicles can all cause our signal to disappear. The bracketry that is used to mount the equipment is critical as well. Using aluminium brackets is not recommended, the preference is steel. This is due to the relative coefficients of expansion, aluminium expands faster than steel and therefore the direct sunlight falling on one side of the bracket causes the expansion of one side of the bracket, with respect to the other. This results in the bracket twisting and the beam is twisted off target and the signal is lost. Whilst steel brackets will have a similar effect, the effect is much smaller and therefore more likely to stay on target.
Ethernet, LAN & WAN
Digital data networks are becoming the norm in many companies for routine data transfer and computer file sharing. If we convert the video signal to a digital data stream, it is possible to use the data network to convey the signal around a building. The problem with this form of transmission is the amount of data required to be transmitted. The majority of existing data networks are such as the 10baseT or 100baseT (10Mbps or 100Mbps). They are used for the transmission of day to day data used in a company and thus there is often some resistance to putting "bl.....y security pictures on my network" from IT managers. The IT manager has to make sure that the software for viewing and control is only put on the relevant PCs in the company, which again can differ from the priorities of the security manager.
Having identified the right people to have access to the images and the sorted out the politics, there is then the practical problem of how many cameras you can have on your network . Images at or near full frame rate will require data streams of around 1.5Mbps for compressed data using ITU H.261 video conferencing techniques and with CIF (small) image sizes. Therefore you could have up to 6 cameras on a 10baseT system before there would be too much data flying around. Alternatively other manufacturers will give you full screen video at 15fields per sec at a data rate of 6Mbps using Wavelet compression, which is only 1 camera on the 10baseT network. But don't forget this is just the CCTV on the network. "What about my precious data" The Network just clogged and nobody could work.
Beware when you look at these systems. Remember that you have to keep both systems working therefore check the networks from all aspects.
Not the hole in the wall where we get our the banks money, but Asynchronous Transfer Mode. A data network that really "cooks with gas", a maximum rate of 2.4Gbps and at that rate it usually has to be provided on an optical fibre backbone. There are a number of manufacturers providing ATM equipment for CCTV such as Baxall & Plettac etc who provide cameras that will either connect directly to the digital network or with their own interface equipment. These are now what can be truly called digital cameras. The signal coming out of the RJ45 connector (or whichever they use) is a stream of binary 1s and 0s that cannot be connected to a standard monitor.
Because of the cost of installing the structured cabling and backbones required for such high speed data networks, it is not yet, in my opinion an economic solution to install fresh for CCTV. However, if you have an existing ATM network, then the option of CCTV over this transmission medium is viable.
This is a new alternative from BT to the well known and loved? RS1000 fibre system they have been providing for a number of years. For long distance transmission the RS1000 has been very expensive. BT have developed RS3000 (HDSL) in parallel with the ADSL system, for use in home and business for "always on" connections to the Internet. The system is provided as a service, at the moment, and you provide a composite video signal at one end and get the composite video at the other end. Unlike ADSL the HDSL is capable of transmission at the same rate both to and from the exchange. It is a point to point link that is cabled on copper to the exchange, so you cannot be further than 3km, along the cable route, from the exchange. The system uses BTs own CODEC and can take one, two or five cameras that share the transmission "pipe". The "pipe" for this service is a 2Mbps shared between the number of cameras the link provides. Because of the nature of the CODECs used it can give a very good update rate for control of pan and tilt cameras.
I am only going to mention that IP addressable cameras are available, because things are moving so quickly that they will be out of date before I finish writing this statement. However, there is much specmanship regarding the performance of the cameras. Very high compression rates and very small images (QCIF) are just two of the ways of overcoming some of the problems with the World Wide Wait. More ominously, if a camera has an IP address and is connected to the Internet then there is a possibility that the camera and receiving computer could be found and the security compromised by your security pictures being watched by those who are not authorised. However watch this space.
Glossary of Terms
ADSL - Asymmetric Digital Subscriber Line, asymmetric because it gives downstream (from service provider to you) rates of 512kbps and upstream rates of 256kbps. An always one connection to the Internet, also used for Video on Demand (Home Choice) and Astreaming video. Provided by telecommunications companies such as NTL and BT.
ATM - Asynchronous Transfer Mode A data network that breaks the data into packets 48 Byte packets and sends them with routing information (5 Bytes).
CIF - Common Intermediate Format. A video format often used in video conferencing systems that easily supports both NTSC and PAL signals. CIF is part of the ITU H.261videoconferencing standard. It specifies a data rate of up to 30 frames per second (fps), with each frame being a size of 352 pixels wide by 288 pixels high.
CODEC - Coder Decoder. A piece of video transmission equipment that converts the signals from analogue to digital and uses advanced data compression techniques including Conditional Refresh.
Conditional The technique of reducing the amount of data to be transmitted or stored, by only
Refresh - sending the data that relates to the changes. In other words only the movement is transmitted (after the original whole picture is first sent).
Data Rates - Data rates in serial transmission, are always expressed as bits per second not Bytes per second so 2Mbps is 2 mega bits per second, not 2 mega Bytes per second.
Ethernet - A data network that was originally provided on coaxial cable
GSM - Global System for Mobile Communication, the current mobile telephone network system.
HDSL - High-bitrate Digital Subscriber Line. The big brother of ADSL. Gives a point to point transmission rate of 2Mbps but is provided as video in to video out.
ITU H.261 - A video conferencing transmission standard that defines the rates and conditional refresh
ISDN - Integrated Services Digital Network. A "dial up" digital telephone system that enables transmission at rates of up to 128kbps
IP address - Internet Protocol address. A series of numbers that uniquely identifies your location such as 188.8.131.52, which is the web page of the Advanced Photon Source, but could equally be a piece of equipment.
LASER - Light Amplification by the Stimulated Emission of Radiation. A Laser produces light that is one wavelength (monochromatic), in phase (coherent) and an almost parallel beam.
PSTN - Public Switched Telephone Network. The standard dial up analogue telephone network that most people have at home.
QCIF - Quarter Common Intermediate Format. A video conferencing format that specifies data rates of up to 30 frames per second (fps), with each frame being only 176 pixels wide by 144 pixels high. This is one fourth the resolution of full CIF. QCIF support is required by the ITU H.261 video conferencing standard. Because the image size is one quarter the size of CIF it transfers one fourth the amount of data and is suitable for video conferencing systems that use telephone lines.
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Reproduced with the kind permission of
What to Buy for Business magazine
Quadrant House, The Quadrant, Sutton, Surrey, SM2 5AS
Tel: 020 8652 8700 Fax: 020 8770 1284
The article was first published in What to Buy for Business magazine in August 2000
You've been framed
Closed Circuit television can cut crime by up to 30%. However, planning and running a system is far from straight forward.
CCTV expert Jon Laws takes a candid look at the issues.
A good investment?
Closed Circuit Television (CCTV) can be a powerful deterrent against crime, and a useful tool for catching offenders. Whether they are used inside or outside, CCTV cameras have a good record in helping to protect property and staff.
Internal and external deterrents
Whether your business is situated in a business park or a town centre, external security can be a problem. However, criminal damage, graffiti and theft from parked vehicles have all been successfully prosecuted and deterred by CCTV systems. In fact, in some areas of the country, Local Authorities are reporting a staggering 85% reduction in vehicle crime - which may in part be due to the spread of external CCTV.
Those who invite the public onto their premises can also use CCTV to improve their internal security. CCTV can help guard against theft of goods by the public and staff. It can also help protect your staff. This is particularly important as the Health and Safety at Work Act requires all employers to provide a safe place of work. CCTV can help with this requirement by deterring violence in the workplace.
Installing internal CCTV can also deter burglary out of hours. If a system is properly monitored it will help in any prosecution.
Despite an urban myth that "digitally recorded evidence is not acceptable in court", digital evidence has always been allowed under Section 69(1) of the Police and Criminal Evidence Act 1984 (PACE).
There are some provisos regarding the correct operation of equipment and handling of data. This position has recently been upheld by a House of Lords committee.
Am I at risk?
If you are trying to assess whether or not you are at risk from particular types of crime and could benefit from a CCTV system, you may wish to talk to your local constabulary. Police Crime Prevention/Reduction officers are normally a good source of advice on the security situation in your area.
Will it pay?
Sadly, in most businesses it is almost impossible to measure the financial benefits of installing a CCTV system. After all, how do you measure the cost of a crime which was not committed? Unless there is a history of regular crime against the property, it is very difficult to quantify the reduction. However, it is possible to ascertain the level of shrinkage both before and after the installation of CCTV, which can help give a measure of improvement. It is even possible that the crime rate could apparently rise after you fit CCTV. (This is a particularly common phenomenon in town centres.) It is normally because the crime is now actually being detected and registered.
What will it cost?
CCTV systems vary in price from £500 for one camera and one monitor (without recording) which may be suitable for a corner shop to town centre systems which can cost around £18,000 per camera. It is even possible to pay as much as £80,000 per camera for a high-end motorway system.
Fortunately, economies of scale can bring the price per camera down. For example, a system of four medium resolution colour PTZ (pan, tilt and zoom) cameras on the same industrial or retail building (which involve no civil works such as trenching to install) would cost about £3,000 per camera position (or £12,000 in total).
This would include such things as video switching and control, recording, display and installation. However, it would not include a console. There are also other costs which you may have to incur. For example, you will have to make the area in which the video recorder is kept secure - or you could risk theft of the taped evidence as well as your goods.
Unfortunately, senior management tend to view CCTV as a loss-making area, rather than one that helps prevent loss. But CCTV can actually be a profit-maker. It may be possible for a larger business with a secure area to create a monitoring centre. This could remotely monitor systems for other local CCTV users out of hours. Remote cameras can be connected to a monitoring centre by normal dial up telephone lines (PSTN), or digital lines (ISDN).
Monitoring initiatives of this type can be co-ordinated by local bodies such as the Chamber of Commerce. In addition, independent security consultants can also offer advice to help identify requirements before investment is made in such an initiative.
The number of cameras you will need will depend not only on the size and layout of the area to be monitored, but also on the type of camera being used. The area a camera can cover is affected by its rotating and zoom capabilities.
Some cameras allow a number of pre-set positions to be programmed in, which are followed either in sequence or randomly. This makes monitoring easier and may make it appear that the camera is actually being manned.
However it is worth noting that, as the direction in which the lens is pointing in a PTZ (pan, tilt and zoom) camera can be obvious, particular care needs to be taken with the housing unit. In such a case it is a good idea to opt for a housing unit which does not show the viewing area, or gives the appearance that it contains several units.
Some companies opt for a dummy camera rather than a fully functioning one. However, this cheap option is simply not worth considering. Most criminals are fully aware of all the different types of dummy camera on the market. The usual clue is the little red light at the front to show it is on. Almost all real cameras have any power indicators at the rear of the camera so they do not interfere with the picture.
Dummy cameras can also pose additional problems. If you fit dummy cameras and a sign announcing "you are being monitored by CCTV", you may leave yourself open to prosecution. For example, if a customer is mugged on your premises, they may ask for the tapes covering the incident. It is then possible that your sign could become misleading advertising.
You could even be taken to Court if the customer claimed they only came into your shop because there was CCTV and thought they would be safe.
Many CCTV systems in small to medium businesses are monitored during the day by local staff. However, at night there is often no monitoring due to lack of resources. This could create problems as potential offenders would be just recorded, without a possible response until after the event.
If you wish to install a CCTV system you will need planning permission, under the Town and Country Planning Act 1990 or Town Country Planning (Scotland) Act 1990 regulations.
There are a few exemptions which apply where the installation is jointly-owned and carried out with the Local Authority.
Applications are tested by the Local Authority using the subjective test - "does it materially affect the appearance of the building?". If it does not, the application will probably be granted. However, there may be regional differences in the way the test is applied.
The less obtrusive the camera, the more likely it is that permission will be granted. This may be why many businesses have installed dome cameras, which blend into the surroundings much more easily than conventional pan, tilt & zoom cameras.
However, if you are considering a dome camera it is also important to note that they are difficult to maintain. For example, it is difficult keep the outside clean - after all, it is nearly impossible to fit a 'windscreen wiper' onto a glass dome.
If you want to install CCTV onto a building in a conservation area, you will have to look far more closely at the effect on the building's appearance.
There is also likely to be more red tape. If a building has a Grade 1, Grade 2 or 2* listing you will have to obtain Listed Building Consent before you may install CCTV internally or externally. In such a case, it is a good idea to carry out a visual survey of the surrounding areas to familiarise yourself with the way bracketry and cameras in other CCTV installations have been designed to blend in to the surroundings.
This can also help to highlight precedent if necessary.
When CCTV is needed
There are also cases where planning permission for new developments, particularly where a liquor licence is required or there are likely to be high concentrations of people, is made conditional on the company funding the installation of a CCTV camera to link into an existing town centre scheme.
These type of requirements tend to vary with the severity of a region's alcohol abuse problems and the coverage of the premises by existing town centre CCTV.
Data protection issues
Most CCTV systems in public areas now need to be registered with the Data Protection Registrar. The Data Protection Act 1998 came into force on the 1 March 2000 and includes the collection, storage and handling of personal data about living individuals.
This includes privately-owned shopping centres and malls, because there is an open invitation to the public to enter the premises, so they are classed as public places.
CCTV system controllers must allow the 'Data Subjects' (which are the videotaped public) to check the accuracy of the information held. This basically means the subject can view the material.
The Data Subject also has a right to a copy of the information (a copy videotape) but they do not have a right to see personal data relating to any other Data Subject.
This implies that the faces of any other Data Subjects in the scene may need to be blocked out. It also means Data Subjects should not be allowed to visit the control room and see pictures being recorded. However, after receiving the application from the Data Subject, the normal processing of data does not have to stop.
Covert recording of employees by an employer is also limited by the Data Protection Act. Data can now only be collected to solve specific problems like fraud, theft or bullying.
There is a possibility that a Data Subject could start civil proceedings against the owner of a CCTV system if material collected by the system is made available to the media and is used. This is because in such cases the data may be being used for purposes other than described under the Data Protection registration.
Further information on the Data Protection Act can be found at the Data Protection Registrar's Website: www.dataprotection.gov.uk
Make your choices
So how do you choose a supplier and are there any standards or regulations they should adhere to?
Is it regulated?
The bad news is that there is no mandatory regulation of the CCTV industry.
However, many systems integration companies are voluntary members of industry inspectorates such as NACOSS (National Approval Council for Security Systems), BSIA (British Security Industries Association) and SSAIB (Security Systems and Alarm Inspection Board).
Members must comply with a code of practice (CoP) for CCTV systems installation. The codes differ from body to body but all set a minimum quality standard, which is monitored as part of an on-going audit of member companies. Violations must be corrected within a specified period. This gives end-users added confidence that a system bought from a member company will be of an acceptable standard.
Users can also take complaints to the relevant inspectorate, so they do not have to go to the expense of seeking legal advice.
Selecting a company
There are a large number of companies with good CCTV skills.
However, when looking at a company it can help to start by asking whether it has experience in your particular industry. It is also useful to ask for references from past clients. You should also check whether the CCTV company provides on-going training to their installation and maintenance staff.
You should also check whether the company is a member of one of the accepted industry associations such as NACOSS, BSIA, SSAIB or ECA Security. It is also a good idea to find out if the company has a quality management system (such BS EN ISO 9000, formerly BS 5750).
The British and European Standard for CCTV, BS EN 50132, is still being formulated. However, the first and most useful part for end-users has been issued and includes the Operational Requirement description and guidance: 'BS EN 50132-7 Alarm Systems - CCTV surveillance systems for use in security applications, Part 7 Application guidelines'. This specification includes details of the Rotakin, a 1.6m tall roughly man-shaped standard test target. The only other part issued is part 2-1 which details requirements for black and white cameras. These specifications are for manufacturers rather than end-users. However, purchasers should note that manufacturers and systems installations companies are not legally required to comply with a British Standard unless it is specified in the Contract. Installation companies are not approved to this standard. Therefore purchasers should be wary of marketing literature or salespeople implying otherwise.
Choosing a system
There are many very capable companies who will design, supply and install CCTV systems. Many companies will have a preferred solution and will keep this equipment in stock. This can be an advantage as it means they can respond more quickly to a request. However, it is possible the preferred solution will not be the most suitable one for your needs. It is important to look at all the alternatives before making your decision. One way of doing this is to employ an independent security consultant who specialises in CCTV. A consultant can carry out a full risk assessment.
In some cases, a CCTV system may not be the best solution for your company at all.
For example, it may be that a good security fence rather than a CCTV system is your best line of defence. After all a fence does not need to be monitored to be effective but a CCTV system usually does.
One of the first steps in purchasing a CCTV system is to establish the Operational Requirement (OR).
This is the system definition agreement which forms the basis for the detailed design. It should be agreed between the client and the installer and will help avoid disputes after installation. For example, issues such as whether the system can be used to read registration numbers may need to be addressed in the OR.
Users are normally asked to define issues such as the purpose for each camera, the image size and whether cameras are required for detection, recognition or identification within the Operational Requirement. Whether the material will be suitable for Court evidence is also an issue which may be need to be included.
ORs also tend to define a standard target which will enable objective testing of the final system to be carried out. This will be required to confirm all the specified criteria have been met. There are a number of documents which will provide help with drawing up a good OR. These include the Police Scientific Development Branch's CCTV Operational Requirements Manual Publication No 17/94 and BS EN 50132-7. Alternatively, a security consultant can also help create an OR.
You may find that CCTV equipment manufacturers try to sell you additional features and functions. Try to stick to the requirements you identified in the OR to avoid being sold something you do not need. For example, some companies sell frame integration for low-light use but it is unlikely you will need this feature.
In addition, while presets, which enable PTZ cameras to be automatically positioned, are useful, few users need more than eight presets per camera.
However, there are some features which you may wish to think about.
If your system will look into public areas you may wish to define privacy zones into which the camera cannot be moved. In addition, where your CCTV system is integrated to another system, such as alarms, a Graphical User Interface (GUI) can also be a very useful feature. If you have such a system and the alarm goes off, it may be possible to show a layout of the alarmed area, select the correct camera and move it to a preset location. You may also be able to display specific instructions for the security guard.
It is possible to opt for digital CCTV. However, unless you have a data system such as an Asynchronous Transfer Mode (ATM) or a Local Area Network (LAN) with a very high data transfer rate (>100Mbps), it will not be economical to install digital CCTV. If you are being offered digital equipment, it is possible all may not be as it seems. Some cameras are called digital but are generally not ATM or true digital cameras (machine vision).
These cameras normally come with Digital Signal Processing (DSP) which means they have some extra features but can be used with a normal CCTV system.
The current cost of digital recording is much higher than the cost of using analogue tapes.
In addition, quality of digital recording quality tends not to be quite as good as an analogue recording on its first day with a brand new tape. However, digital quality is constant and replay is very good with noiseless freeze frame.
Buying and running
There are four basic ways of purchasing a CCTV system:
1 by capital purchase;
2 by lease purchase;
3 lease; and
Although the on-going cost of renting or leasing is normally higher than capital or lease purchase, these methods usually include fully comprehensive maintenance within the contract terms. However, it is possible to be locked into contracts for up to seven years, which may cause problems. CCTV technology changes very rapidly, so it is possible a system could be out of date in as little as three to five years. It is generally accepted that the capital purchase is the best route, with the value written off over four years but with a life of up to 10 years if properly maintained.
On-going costs include maintenance, monitoring staff and consumables. The highest cost will probably be monitoring staff.
For example, a dedicated control room merely undertaking CCTV monitoring would need a staff of between five and eight people for a three-shift system. In addition, cover for absence sickness and annual leave could also be required.
This could cost up to £60,000 annually. The average operator can efficiently monitor up to 32 images comprising eight quad (four pictures per screen) monitors, if they know the area they are monitoring and concentrate on areas which are more likely to have trouble. Some companies run their CCTV monitoring on 12-hour shifts. However, this can greatly reduce the efficiency of your monitoring staff.
Other companies also give monitoring staff other secondary tasks. This can introduce variety and help improve efficiency. It is important to note that both the system manager and operating staff will need formal training, which can be provided by specialist training centres such as Tavcom Training.
Comprehensive maintenance cover could cost about 15% to 20% of the equipment's initial cost each year.
If you do not have a fully comprehensive contract, you will be subject to call-out charges or the cost of replacement equipment if things go wrong.
Most contracts do not cover vandalism and misuse. Similarly, cost of consumables such as lamps for Infra-red illuminators and video recorder heads are often excluded.
Manufacturers recommend replacement of video heads every 10,000 hours but it is a good idea to replace them once a year (or after 8,760 hours) if your recorder operates 24 hours a day, seven days a week.
It is also a good idea to note the average life of the lamps so preventative maintenance can take place to minimise downtime.
At present, there is no compatibility of recording media between manufacturers. This is even the case where the same type of recording medium, e.g. Digital Audio tape (DAT), Digital Versatile Disc (DVD) or Digital VHS tape (D-VHS tape) is used.
This can lead to the Courts, amongst others, having problems with the exchange of evidence.
An industry group, the Digital Forum, is trying to establish standards in digital recording file exchange formats to avoid these compatibility problems.
Points of contact
Information on the CCTV market is available from the following sources.
Association of Security Consultants
PO Box 22,
Middlesex TW12 3HL.
Tel: 07071 224865
British Standards Institution
389 Chiswick High Rd,
London W4 4AL.
Tel: 020 8996 9000
Data Protection Registrar
Cheshire SK9 5AF.
Tel: 01625 545700
British Security Industries Association
Worcester WR1 1RS.
Tel: 01905 21464
The Lyndhurst Consultancy,
PO Box 631A,
Surbiton KT6 6WN.
Tel: 020 8288 8246
National Approval Council for Security Systems
14 Cookham Road,
Berks SL6 8AJ.
Tel: 01628 637512
Police Scientific Development Branch
Herts AL4 9HQ.
Tel: 01727 865051
Hampshire SO32 1GN.
Tel: 01489 985099
The Electrical Contractors Association
34 Palace Court,
London W2 4HY.
Tel: 020 7313 4800
A selection of CCTV installation companies operating in the UK have been included here.
These contact details are intended for information purposes only, and inclusion on this list
does not constitute a recommendation. Names of further installation companies are available
from the various industry bodies listed above.
ADT Fire & Security Plc
Sunbury on Thames,
Middlesex TW16 5DB.
Tel: 01932 743456
Bell Security Ltd
970 Romford Road,
London E12 5LP.
Tel: 020 8553 5932
Unit 2, 225 Hook Rise South,
Surrey KT6 7LD.
Tel: 020 8974 2244
Eurotech Security Systems Plc
2 Crescent Road,
London N22 4RS.
Tel: 020 8881 4174
Orbis Security Systems Ltd
11 Abbey Mead Industrial Estate,
Essex EN9 1HU.
Tel: 01992 788885
Cambs CB1 3HE.
Tel: 01223 245191
Photo-Scan Systems Ltd
Sunbury on Thames,
Middlesex TW16 7HG.
Tel: 01932 898500
Quadrant Video Systems Ltd
3A Attenborough Lane,
Nottinghamshire NG9 5JN.
Tel: 0115 925 2521
62 Grayshill Road,
Westfield Industrial Park,
Cumbernauld G68 9HQ.
Tel: 01236 457724
West London Security
19 Stannary Street,
London SE11 4AA.
Tel: 0207 823 2077
This article was first published in Croners "Premises Management
Bulletin" Issue 73 March 1999
Croner Publications Ltd
Kingston upon Thames
Tel 020 8247 1176
CAMERA AND SENSOR TECHNOLOGY
The advent of the charge-coupled device (CCD) sensor was hailed as being the end
of maintenance of cameras. For a short while, this is actually appeared to be true, but
only with the simple CCD chips of approximately 10 years ago.
What is a CCD Chip?
The CCD chip is actually an array of thousands of photosensitive diodes arranged in
a matrix. Associated with every photodiode is a metal oxide semiconductor (MOS)
capacitor which is used to retain a charge, built up during the field period of the video
signal. An analogue shift register also forms part of the CCD chip and the shift register
forms the other part of what is often known as a bucket brigade device. The buckets are
the MOS capacitors and the brigade refers to the analogue shift register. The charge
is passed from bucket to bucket through the device.
The advertised advantages of CCDs are that they:
(a) are solid state
(b) have no electron beam
(c) are almost immune to magnetic or electric fields
(d) are not susceptible to vibration
(e) have no burn in
(f) need no adjustments
(g) need no changing of tubes
(h) have an unlimited lifetime.
However, the reality of the situation was less than perfect. The CCD chips gave a lot
lower resolution (approximately 240 lines on the first devices) and also had a lack of
ability to deal with the extremes of light level. Thus, all lenses had to have auto iris
control, whereas the Vidicon tubed cameras did not require auto iris controlled lenses,
but used manual iris lenses.
The early CCD chips were all frame transfer devices, which were also less sensitive
than the tubed cameras chosen for outdoor use. Interline transfer devices then
improved the sensitivity, but brought a crop of problems, such as transfer smear (see
below). The unlimited lifetime of the CCD chips is true to some extent, but the life is
limited by the very rapid advances in chip design — making obsolescence the limit of
lifetime of the chips.
Types of CCD Chips
At present, there are both monochrome and colour CCD chips, in both single and three
chip combinations. It is possible to achieve more than double the early resolution, ie
up to 570 lines in monochrome and up to a supposed 480 lines in colour (only
achievable at the chip, which very few manufacturers mention). The sensitivity of the
CCD chips has improved markedly since their introduction.
During the 1990s, there have been two basic types of CCD chip, ie the frame transfer
and the interline types.
The frame transfer chip has two distinct sections, ie a photosensitive area and a
storage section. The focussed image is projected onto the photosensitive area, thus
causing the charges to be defined in the chip. The storage area is masked from the
light using an opaque aluminium optical mask. Every one-fiftieth of a second, a field of
information is transferred from the photosensitive area to the storage area, where it is
then processed during the next one-fiftieth of a second.
The interline transfer chips have shift registers between the columns of pixels. This
enables better processing to be carried out, although light leaks onto the shift registers.
Although screened, light does penetrate and generates electrons deep within the chip
where there are large overloads. These deep electrons add to the charges being
transferred in the registers, an effect which is typified by a vertical red or white line
down the screen, known as transfer smear.
For many years the manufacture of CCD chips was dominated by one manufacturer,
but there is now competition. The types that are now practical devices are hyper hole
accumulated diode (hyper HAD), super dynamic, frame interline transfer and the
Hyper hole accumulated diode
The hyper HAD was released in 1990 and introduced a number of improvements in the
design of interline transfer devices. These improvements serve to reduce the dark
noise which could be purely from:
optical shot noise
fixed pattern noise
residual point noise.
Due to the improved sensitivity,which is largely a result of the on chip lens, it has
rendered the use of electronically-controlled shutter speeds, to be a far more reliable
method of controlling the exposure. There is also an improvement in dealing with
transfer smear, because of careful profiling in the design of the chip.
This is a recent refinement in the design and manufacture of interline devices where
the number of vertical shift registers has been doubled, thus enabling charge generated
by the photodiodes to be dealt with in two different ways.
The overall scene is processed and the exposure of the photodiode is determined by
the light falling on the photodiode. For dark parts of the picture, the photodiodes are
exposed for almost one-fiftieth of a second. The parts of the picture with highlights
(where light levels are high) will be exposed for a far shorter period of time, perhaps as
short as 1/2000th of a second. The short charge and the long charge are processed
together which results in the output picture. This technique gives dynamic light
handling, better than 20-40 times that of the conventional hyper HAD.
Frame interline transfer
This type of device combines the benefits of both the frame transfer and the interline
The chip design features a masked storage area exactly along the lines of the frame
transfer chip. Every one-fiftieth of a second, a field of the generated charges is
transferred straight into this storage area. From here, the information is then the
processed line by line, in the manner of the interline transfer device.
In dealing with the charges in this manner, almost all the problems of generation of
deep electrons within the semiconductor are avoided and this results in an
improvement of the transfer smear by reducing the levels by a factor of approximately
60. This technique was designed a few years ago and was used exclusively in
broadcast cameras. It was considered too expensive to use in CCTV, but it is now
possible to obtain the appropriate chips.
Exwave, in this case, means extended wavelength, because the chip has an improved
spectral response. It gives approximately double the sensitivity at 800nm and
approximately four times the sensitivity at 900nm (both being in the infra-red
wavelengths). This diode has greater sensitivity in part because of the on chip lens
design and the improved masking of the vertical shift registers, giving less transfer
What comes out of the back of a camera? Answer — a mains cable! This is a genuine
answer given by a delegate on a training course, but it does raise the question of what
is the right answer? The real answer could have been any one of the following:
(a) composite video
(b) horizontal synchronisation pulses
(c) vertical synchronisation pulses
(f) RS 485 data
(g) data, as defined by the Data Protection Registrar.
Is it all necessary? With tube cameras, the controls that were available were all
necessary to enable the maintenance of picture quality over the two year period or so
between tube replacements. Such controls were electrical focus, target voltage, the
current and pedestal. For a while CCD cameras were very simple, ie they were MOS
cameras that had no controls that were user configurable. However, many cameras
now contain such features as line phase, genlock, chrominance, peak white blanking,
auto white balance, auto white tracing, text and clocks, auto iris settings, direct drive
iris outputs, peak/average adjustment, electronic iris, manual shutter selection, high
light suppression, Y & C video outputs, picture memory, movement detection, backlight
compensation, kangaroo lens drive, output level adjustment, user memory settings,
motorised back focus, field integration, DSP, security code, remote controllable
functions, on-screen menus, and restore factory default. A brief overview of these
functions is given below.
1. Line phase enables a.c. powered cameras to have the line phase adjusted to enable
multiple cameras to be switched through a simple analogue video switch without the
resultant picture bounce of unsynchronised cameras.
2. Genlock is an input to enable all cameras to be synchronised to a single
3. Chrominance usually enables the increase and decrease of both red and blue,
manually (there is not usually adjustment of green, because adjustment of red and blue
will give the impression of increasing and the decreasing the level of green, ie red and
blue and green = white).
4. Peak white blanking describes the situation where highlights of approximately 150%
or more will be changed from a peak white to either black or a shade of grey to enable
darker parts of the picture to be seen.
5. Auto white balance means that the camera decides on what is white within a picture
and compensates by adjusting the colours to achieve this white level.
6. Manual white balance is the facility whereby at the commissioning stage, the camera
is provided with a “white target” filling the screen this is set as white, normally by
pressing a set button.
7. Auto white tracing is useful where the colour temperature of the lighting may change
with time or as external lighting changes.
8. Text and clocks can be programmed either at the camera only or from the control
room; it should be noted that the remote programming of text can be considered a
potential problem when evidential material is being collected.
9. Auto (video) iris settings involve an output known as a digital auto iris; this output
used to be a video signal, but is now an integrated signal which can cause problems
when used in combination with some lenses — making the setting of iris level a very
twitchy thing to do.
10. Direct drive iris removes the control electronics from within the lens and relocates
them to within the camera, thus allowing the purchase of cheaper, lighter lenses.
11. Peak/average is an adjustment which gives the commissioning engineer the
opportunity to change detection between peak within any part of the picture or an
average over the whole picture.
12. Electronic iris enables the use of a manual iris lens, so the camera now controls the
exposure of the CCD chip by changing the shutter speed continuously to suit the
ambient lighting conditions.
13. Shutter is the equivalent of the shutter adjustment on a photographic camera, which
helps to stop blur due to motion of the object. The higher the shutter speed the greater
the amount of light that is required. It can also be used to overcome the problems with
having a 60Hz mains frequency, but using systems at 50Hz, such as in Saudi Arabia,
produces the effect of a visible pulsing of the lighting.
14. Y-C video outputs enable the highest resolution colour signal to be transmitted and
recorded (recording as SVHS). However, it requires two transmission paths and two
matrix inputs per camera.
15. Picture memory can enable one field of video to be stored in the camera in response
to a stimulus.
16. Movement detection uses relatively simple movement detection criteria, such as
video level detection, to determine if there is movement within the field of view; it will
then signal (via telemetry) that there is movement within the picture, but should never
be considered as an alarm device.
17. Backlight compensation is used to deal with the problem of backlighting that causes
people and objects to be silhouetted.
18. A kangaroo lens drive is an output to drive the latest two position iris lenses being
used with electronic iris and field integration.
19. Output level adjustment is used to boost the video signal prior to transmission on
longer lengths of coaxial cable.
20. Memory settings — in some cases, up to four different memories can be available
to memorise the multitude of settings required for the operation of the camera.
21. Motorised back focus can simplify the pre-assembly or the installation of cameras
and can aid where infra-red lighting is used, causing a change in focus.
22. Field integration is very useful when lighting levels are very low, but should be used
with caution and (realistically) only with fixed cameras, because of the amount of blur of
even slow motions that can be seen when using long integration periods.
23. Digital signal processing (DSP) can improve the resultant image by defining outlines
by introducing a one pixel wide black line around any objects within the scene to improve
visibility where the levels of contrast are low.
24.Security mode ensures that if a camera has been stolen, it cannot be used unless a
code number is entered to prove ownership.
25. On-screen menus have become more essential with the increase in the number of
features of modern cameras.
26. Restore factory defaults can be an essential item where an engineer has finger
trouble (they all do) and has forgotten where he was when he started; this feature should
only be used as last resort and it is essential for all the settings to have been
documented carefully for each camera within the system.
The above list includes 26 different features, but users should be careful that their
manufacturers give independent views. Who have the marketing strategists targeted?
Have they persuaded the consultants that there are particular sets of features which are
essential for every job they may be specifying? Alternatively, has the control room
manager been given demonstrations of the camera in the controlled environment of a
dark room or perhaps even a demonstration vehicle in his or her own locality, but with
the highly trained manufacturer’s operator driving the demonstration camera? At this
stage of the proceedings, it is very unlikely that the control room operators have been
interviewed, let alone had some training and commented which features may or may not
It is inevitable that as camera features become more varied, so the operation of the
system will become more complex. There will be more adjustments to make to the
system on a time-profile basis. This is one particular aspect that can be simplified by the
availability of user configurable memories within the camera to enable different settings
to be chosen, depending upon the ambient conditions. It must be remembered that this
will also involve the operator having a good memory or clear concise documentation
within a busy control room environment.
Controlling the Features
Another word of caution is that it must be clearly remembered that to have all these
advanced features available for your system, that you must have the camera
manufacturer’s telemetry control system. This choice of the control system may lead to
restrictions of hardware that may not (at first) be evident. In other words if we fitted one
camera with remote control of back focus into another manufacturer’s control system,
you cannot, without modification to the system, control the back focus. This design and
modification can be carried out, but puts a premium on to the price of the control system.
There is much talk of digital cameras, and some of the commonly available cameras
actually have the word mentioned on the body of the camera. However, there are only
a very limited numbers of true digital cameras available and they are attached to a
computer, used in videoconferencing applications. The current restriction is the data
transfer rate; for high-quality video in a serial data stream, transfer rates of greater than
250 Mega bits per second are needed. Clearly, the current transfer rates over ISDN are
totally inadequate, but if there is a parallel data bus system of, say, 32 bits’ width, then
the data rate reduces to approximately eight Mega bits per second.
There is currently much work being done with asynchronous transfer mode (ATM)
networks, ethernet and the like, for both serial and parallel data transmission. However,
for the immediate future, it is unlikely that digital cameraswill be appearing in town
centres until the fibre optic equipment manufacturers can provide an economic bearer
Similarly, there is no established standard yet for the compression of video for both
transmission and storage. Will it be MPEG, JPEG, wavelet or even fractal compression?
Any digital cameras that purport to use IEE1394 bus are cameras for machine vision and
will feed into a PC and not a video matrix. The transmission distance on copper cable
is rather limited as well — only 4.5m!
Some people have been slightly misled to believe that digital signal processing (DSP)
cameras are digital cameras, but all DSP cameras still have an analogue video output.
The DSP aspect relates to signal processing within the camera, that is used to enhance
various aspects of the video output. DSP can be used to give sophisticated backlight
compensation and the aspects of motion detection that some manufacturers include.
When an area being observed is low contrast between the objects and the background,
DSP cameras can enhance the outlines by drawing a one pixel wide black line around
all of the objects, both foreground and background, thus giving well-defined edges. It
should be noted that some cameras can introduce so much processing that post-
production video enhancement, such as used by courts for evidential purposes, cannot
actually improve the pictures further.
There has been a great tendency to reduce the size of the CCD chip and the cameras,
driven largely by the camcorder market, which has led to the development of the covert
spy-type cameras. With large-scale integration, the CCD chip and lens can be separated
from the rest of the electronics to produce cameras that are fitted into pens and
spectacles, which then combine with miniature video transmitters to enable the remote
recording of those pictures. It should also be remembered that under the Data Protection
Act 1998, all personal data must be fairly obtained.
Another area of development relates to thermal imaging cameras which, only a few
years ago, required the detector devices to be cooled by the liquid nitrogen. It is possible
now to purchase a hand-held thermal imaging camera, with a fixed lens, and no external
cooler, for under £14,000. Similarly, there are now image intensifiers that can be fitted
between the lens and the CCD chip to give performance in lighting conditions down to
starlight (0.0001 lux) and they cost less than £10,000.
There are also cameras that can give up to 700 lines of resolution, but these are limited
to broadcast applications with cameras being priced from £20,000 upwards (prices and
sizes are dropping fast). Caution is needed when looking for these high resolutions,
because they are obtained using three separate CCD chips and lenses with prisms fitted
to split the light. These cameras give four output signals, as red, green and blue and
synchronisation (sometimes three, ie RGB with synch on green) and, therefore, require
four separate cables and four channels per camera in the matrix switch. A standard
industrial timelapse VCR will not be able to record this form of signal.
Users should consider carefully the ramifications of installing increasingly complex
cameras and control systems. The man machine interface or graphical user interface
or keyboard needs to be as simple as possible, to enable operation and management
of the system to be as effective as possible.
Top of Section
DESIGN CONSIDERATIONS FOR PUBLIC AREA SURVEILLANCE
The rate at which CCTV systems have been installed in Britain, has far out
stripped the rate at which Standards (British or European Standards) have been
written and introduced, which has created its own set of problems.
To date, we have two parts of the British and European Standard for CCTV,
BS EN 50132, Part 2 –1 Black-and-white cameras and Part 7 Application
guidelines. For the majority of systems installed in town centres, we can
disregard the specification for black-and-white cameras, because colour cameras
predominate. Whilst, since the 15th of September 1996 (the date Part 7 of the
Standard was introduced) the number of Town Centre systems requiring
compliance with Part 7 of the Standard, can probably be counted on the fingers
of both hands.
The lack of such standards has made the design of such CCTV systems
inconsistent, which will certainly make the task of the new CCTV User Group,
Accreditation by Assessment, more difficult. However, the saving grace is that
the assessment is based more on the operation of the system, than the technical
design. We have had various codes of practice for the operation and
management of CCTV systems which has given some consistency. There is
likewise a draft Code of Practice being considered by the British Standards
Probably the most obvious and powerful restraint in the design of any CCTV
system is that of available finance. Having therefore defined the maximum
number of cameras that it is possible to install, we need to look at the location of
those cameras. It is often the case that the first locations chosen to install
cameras will be on buildings. This can often appear to reduce the costs by not
requiring the installation of specialist camera columns, however, by installing on
the building we can incur major hidden costs, because of the complexity of the
process required to obtain “Way Leaves”. A perfect example of which is, a
national chain of chemist shops in a building in the West of England who are
leasing the property from the owner who is a County Council in the East of
England. The hidden costs therefore, are those involved with the lengthy
negotiations between the solicitors of the three parties involved, along with those
of extending the contract because of delays caused by the negotiations. Thus it is
often the case that the use of a specialised camera column will give a lower total
cost than installing the camera on the building. The other added benefit is that
when a camera is mounted on a column in the pavement, we will often find that
the views afforded from this vantage point are better than would be obtained
from the building mounting, because of the shape of the buildings in both
directions up the street.
If the intended building is a “listed” building, then we have even more potential
complications. We have not only to obtain a Way Leave, but also permission to
mount the camera on the listed building, which involves at least two more
interested parties the Local Authority planning department and English Heritage.
In many towns there are conservation areas where the indiscriminate installation
of camera columns without consideration for their design would constitute a
major problem. The design, by Welding Engineering Limited, of a cabinet based
column to enable the mounting of transmission equipment, electricity board
supplies as well as telemetry receiver equipment, has meant that only one new
piece of street furniture is required, rather than the three pieces that were
previously required (column, transmission cabinet and Electricity board pillar).
There has also been the recent development of the dual function camera column.
This enables an existing street lighting column to be removed; it can then be
replaced by a column, with a camera mounting position at say 6 m and a street
light mounted on an extension above the camera at 8 m. The electricity supply
for the street lighting is then re-connected and now supplies the camera as well
as the street light. Where the camera is being located in a conservation area it is
also possible for the column to be painted to match surrounding street furniture
and the design to include gold or silver banding, scroll work and finials. A
similar philosophy of blending building mounted camera bracketry to match
existing lighting fixtures can be applied.
Such customised metal work and finishing, can be made by these specialist
manufacturers, to suit any location or match any existing design. But bear in
mind that the more unusual the design, the larger the bill will be. It is therefore
very important to ensure that if there are any areas within the scheme, that may
require input from the “Heritage” section of the Authority, that such input is
sought before the contract goes to tender. The costs will therefore be kept to a
minimum because there are no “extras” and no hidden costs due to delays.
Two brief words of warning. First, consider whether to install anti-climb spikes
because some individuals consider it a challenge to climb a 6 m camera column
to get to a camera. Second, ensure that the camera mounting nuts and studs are
below the finished ground level, because there have been incidents where
exposed nuts have been undone.
Overt or discrete
There is always the quandary as to whether the system should be overt or
whether it should be more discreet and blend into the background. A problem
with the overt (conventional pan & tilt) is that whilst it has a reasonable deterrent
effect, the nature of the assembly is such that it is obvious which way it is
pointing. As a result there have been incidents where a couple of friends appear
to start a fight to catch the attention of the operator, while others in the group can
see the camera pointing away from them while they commit a Smash & Grab
One may be led to believe that dome cameras are the answer. Such is not the
necessarily case. Dome cameras have their own peculiar set of problems such as
the optical quality of the dome , which means that they should not be used with
very long focal length lenses. Keeping the dome clean is always a problem, the
person who can design an effective windscreen wiper for a dome, could make a
fortune. Dome cameras do however, blend into the background more easily and
they have the benefit of not obviously showing the direction in which they are
When at last, the system goes live, the usual blaze of publicity is more than
enough to send a warning to the “bad guys” of the area. Having had this warning
the “bad guys” will be able to spot the cameras whether they are overt or
discreet. The casual wrong doer is probably drunk and does not care whether he
can be seen or not and probably couldn’t spot an overt camera unless pointed
out. So does this mean that the cameras should blend in discreetly, matching
surrounding colours where possible, whether they are conventional design or
dome type cameras?.
The Help Point
With the advance of technology regarding transmission equipment, we now have
the opportunity of multiple services on a single optical fibre. There are an
increasing number of CCTV systems that are having a Help Point system
integrated with their video transmission. The Help Points can be located either in
the street, usually mounted on the camera column, or in car parks monitored by
the CCTV system. The usual form is a weatherproof intercom, which when
triggered will signal the operator and will often automatically send the nearest
camera to a preset position showing the Help point in use. These can be used as
either panic points or for general information. They are yet another way of
reducing the fear of crime in public areas and increasing public use of town
The Control Room
What about the design of the Control Centre (room) itself? We have two British
Standards that define the construction and security of the control room, namely
BS 5979 and BS 7499 but these are for such things as Alarm Receiving Centres
(ARC). There is, as yet, no standard for the design of the CCTV Control Room.
However, there are an increasing number of CCTV Control Rooms that are being
called upon to fulfil many other functions in addition to monitoring CCTV
cameras, so the basic philosophy is sound. Alarm receiving, video confirmation
of alarms, key holding and social alarms are some of the other functions fulfilled
by the sometimes over stressed CCTV operator.
Does the Control Room require heating in the Winter? Possibly only a small
amount because of the heat generated by all the equipment, but it must be
considered.. The heat dissipated by all the equipment needs to be calculated for
the absolute maximum capacity of the system, to ensure that the air-conditioning
or cooling system is correctly sized for all of the equipment and people expected
in the room.
While considering the amount of power dissipation, it is wise to consider the
total amount of power required by the control room. This will enable an
Uninterruptible Power Supply (UPS), to be sized for either the maximum likely
power cut duration or to enable standby generators to be started and reach full
A consideration that has previously not being taken into account in the layout of
many control rooms, is that of tape review. Often the review suite is no more
than a desk with a VCR, multiplexer and a monitor in the corner of the control
room. Under the Data Protection Act 1998 the majority of town Centre CCTV
systems will have to be registered for the collection of personal data (video
images of people stored on tapes). This means that the data subjects (people)
have the right to check the accuracy of the personal data (video images) held
about them. The data subject (person) does not have the right to view personal
data relating to any other data subject. Thus, by having the review suite in the
control room, the data subject wishing to check his or her personal data, will
have sight of personal data being collected relating to other data subjects ie.
images on the monitor screens, to which they have no right. There is also the
added complication that any visitor to the control room, can be called as a
witness to an incident if they were to see it during their visit to the control room.
Tape storage and management is another area that can be easily overlooked. A
typical town centre CCTV system with say, 50 cameras will require seven time
lapse VCRs, each requiring three tapes per day, plus at least three real-time
VCRs for incident recording, again, each requiring three tapes per day. When
tapes are archived for a period of at least 28 days, we have a total requirement of
840 tapes. For every incident requiring video evidence from tape, we will lose
two tapes to the Police or Courts, so with one such incident a week we will need
a further 104 tapes, which will need replacing annually, making almost a total of
1000 tapes a year. As a further requirement of the Data Protection Act, the
personal data we collect must be held securely so that access must be restricted
to authorised personnel only.
These are some of the major design considerations required for any town centre
CCTV system. There are any number of others, which is why it always pays to
employ a specialist consultant to ensure all aspects are covered.
For those who may be interested in the design of control centres or who are
involved in providing equipment or services within a control centre, there are
currently two draft standards released from the BSI for public comment. They
are BS EN ISO 11064-1 & -2, Ergonomic design of control centres - Part 1
Principles for the design of control centres (comments required by the end of
May): and Part 2 Principles of control suite arrangement (comments required by
the end of June). These draft documents can be obtained from Customer
Services, Committee PH/9/6, 389 Chiswick High Road, London,W4 4AL. Tel
0181 996 9000.
Further information regarding the Data Protection Act can be obtained from the
Data Protection Registrar, Wycliffe House, Water Lane, Wilmslow, Cheshire,
SK9 5AF Tel 01625 545742.
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