VOSCOM Fiber Optics Blog

In any integrated security and surveillance solution, transmission is often taken for granted. It is simply assumed that it provides relevant capacity to transmit video and audio data, and that it can handle expansions and integrate new technologies in the future. However, if the transmission is not designed correctly from the onset, making it right later on can be costly.

Making sure that transmission is able to cope with system requirements now and in the future is not only key to a future-proof security and surveillance system, it also allows for easy and cost-effective expansions.

There are, however, many transmission technologies and media available; hence, deciding and designing the appropriate solution is not necessarily straightforward.

This article highlights the advantages and disadvantages of different technologies and designs and will, hopefully, provide some guidance in terms of how one can avoid some of the usual integration and configuration bottlenecks.

With a completely new project with no legacy technology involved, the first thing you have to consider is which signal format you plan to use — that is, compressed or uncompressed video signals.

If you start a network from scratch, this decision has major implications for the transmission network and medium(a) you design your network around.

Depending on the distances involved, choices for compressed video signals include coaxial cables (Cat-5/6), fiber optic transmission (multi-mode optical fiber  or single-mode optical fiber, CWDM or DWDM), Ethernet, wireless transmission (unlicensed or licensed frequencies) or a mobile network.

If you need to transmit uncompressed video signals, media include coaxial, twisted pair, wireless and optical, depending on your requirements and distances.

The physical layout of the network — the topology — is often a function of the geographic distances and transmission medium(a). The topologies usually employed are star (also known as point-to-point), ring, bus (also know as spur) and mesh (a combination of star and ring. See <Figure 1>.

In many projects, however, there is either some legacy equipment involved in the transmission. Or, there may be other specific requirements which necessitate the consideration of one more element, namely the mixture of signals on the network:
* Uncompressed, all analog: analog cameras and analog transmission
* Compressed, all IP: network cameras and IP transmission
* Hybrid: analog cameras, analog and IP transmission
* Mixed: analog and network cameras, analog and IP transmission

Uncompressed
In an ideal world, an uncompressed network would be preferable, as it affords the highest video quality for PAL/NTSC cameras and is well-understood for easy installation and maintenance.

You have a number of vendors you can choose from, although some solutions are considered proprietary. <Table 1> shows the advantages/disadvantages of the various media for uncompressed transmission.

Uncompressed Transmission

Compressed
The main advantage in a compressed transmission network is that it allows video to fit into the global IP standard.

As HD cameras are beginning to gain traction, the technology will gradually offer resolution benefits over uncompressed PAL/NTSC video. It is important to note, however, that a compressed solution can be limited in frame rate, can have issues with the temperature range it is operating in, and may have low-light performance issues.

On the other hand, a compressed solution can use existing network infrastructure, such as Ethernet. Another thing to take into consideration is that historically compressed solutions have been troubled by algorithm obsolescence and vendor-dependent algorithm implementation. Further, there are trade-off issues with quality, latency and bandwidth.

Now, we are seeing more multivendor protocols emerging, requiring IT skills to install, commission and maintain networks. <Table 2> shows the advantages/ disadvantages of the various media for compressed transmission.

Compressed Transmission

Hybrid Networks
A hybrid solution employs analog cameras with analog transmission to a control point/room where you then apply video compression. An IP network is used to link the control points together. One could argue that a hybrid solution offers the best of both worlds. It gives you the largest choice of high-resolution cameras while retaining a high degree of security integrity because it keeps IP away from the edge of the network.

It allows for easy upgrades of compression equipment while retaining the benefits associated with analytic software, which you do not have to install at the edge of the network, providing you with the highest quality signals available for content analysis. You have the flexibility to install analytics on any camera in a controlled environment, even deploying different software on different cameras for easy upgrades. Best of all, you can work with a multivendor system.

Mixed Networks
Mixed networks tend to be legacy-based, and they allow you to mix HD compressed cameras with PAL/NTSC uncompressed cameras. This caters for the application of centralized analytics on PAL/NTSC cameras and allows you to choose the best-of-breed technology for each location need. It further allows you to build a multivendor system.

How to Decide?
Start by considering all the technologies and topologies available to make sure you design a network based on the requirements of your given project. Many users are not aware that the requirement specification is actually not a technology specification. You need to make informed decisions with respect to picture quality, maintainability, resilience, cost, security and future requirements.

Only when you have considered these elements can you effectively decide the technology best suited for your particular project. In terms of topology, a point-to-point system may require the lowest initial equipment cost, but may be expensive in terms of maintainability, resilience, scalability or manageability. The more significant the requirement is in terms of security, the more up time and resilience matter in the transmission topology selected.

The principle reasons for using optical fiber as the transmission media in CCTV applications are:

·  The maintenance of picture quality and control data integrity over extended distances:
This is the major reason for using fibre optics which have superior signal amplitude loss characteristics than copper cable. Typically co-axial cable attenuation at a signal frequency of 5 MHz can be 20 dB/km. In comparison fiber attenuation is between 0.3 and 3 dB/km meaning that fiber optic transmitter distances of 60 km+ can be achieved, depending on the precise details of the application. In addition this low fibre signal attenuation is achieved over a very wide signal frequency range so that optical fiber can be used for the transmission of multiple video signals over long distances.

·  Immunity to electromagnetic interference:
Optical fibre transmits signals as light pulses rather than electrical pulses. This light transmission is unaffected by the presence of electro-magnetic fields. As a consequence fiber optic transmission can be used in applications where links are routed near electrical conductors and electrical machines. This includes applications such as railways, tramways, power generation and vehicle manufacture with welding machinery. In addition the fibre cable usually has a metal free construction so that there are no ground loop problems between terminal equipment and the cable will not transmit lightning pulses. This elimination of ground loops makes fibre cable the media of choice for inter building links of whatever distance.

·  Security of Information and Operational Safety
Unlike copper cables fiber cables do not radiate any signals as a consequence fiber optical cables are virtually immune from “tapping” and so the signal content is difficult to access for unauthorised parties. As there are no emissions from optical fibre cable there is no risk that a fibre installation will act as a ignition source. This means that fibre can be used in explosive atmospheres such as chemical and petro-chemical sites providing a truly “Intrinsically Safe” transmission path. Note however, that this Intrinsic Safety, would not extend to the electro-optic termination modems which would need to be safety certified and protected the same as any other electrical equipment.

·  Efficient use of duct space.
Optical fibre itself is very small, each glass fibre being only 0.125mm diameter. Protective sheathing is then applied in stages, depending on the application area, to make up the fibre into a usable cable. Typically resulting cable would have a diameter of 3mm for a single fibre core patchlead or 8mm for a 8 fibre cable suitable for internal or external use. In contrast 75 Ohm CT100 coaxial copper cable has a diameter of 6.5 mm. It can therefore be seen that the small size of fibre cable gives significant savings over copper where installation space is in short supply or where duct space is limited. Along with the small fibre cable size comes a weight saving both of which give savings in storage and transportation costs prior to installation.

·  Multi-channel capability and “Future Proofing”.
While most CCTV fibers today will be used to transmit one video signal and perhaps a control data signal, the user may wish to upgrade the system to support more camera and control channels. Any glass optical fiber used today is able to transmit multiple optical channels either by using different optical carrier “colours” i.e. wavelength division multiplexing or by increasing the signal frequency using electrical multiplexing techniques. The transmission media is hence “future proofed” and the link will need only additional fiber optic converter equipment to expand the link capacity.

The use of fibre optic transmission is now commonplace in telecommunications, data communications and broadcast quality television signal applications. In contrast the use of optical fibre as the transmission media in CCTV security and surveillance applications is a relatively recent development fuelled in the 1990`s by the need for the installation of
extensive CCTV systems to combat crime, vandalism and terrorism. Conventionally cameras are linked to monitors over copper cable links using the lowest cost components available. As system size has increased the distance between cameras and monitors has also increased resulting in an unacceptable degradation of received video signal quality. i.e.
received picture quality, for link distances over 100 – 150 m. This has meant that the use of optical fibre transmission has had to be considered even in this most cost conscious of applications.

In these sections we will attempt to de-mystify fibre optic transmission as applied to CCTV system use. We will start by outlining why fibre optics should be used, go on to consider the basic elements of a fibre optic converter system and installation practice and finally outline the technology to extend CCTV systems from essentially local installations to extensive, distributed multi-channel signal transmission systems.

CCTV and surveillance technology is constantly evolving and today’s digital IP cameras provide increasingly sophisticated capabilities for monitoring, recording and reviewing activity inside and outside your property. With a wide choice of products available, understanding your options can be confusing, whether you’re new to CCTV or planning to upgrade an existing system. Here are the top ten things you need to ask yourself to get the right CCTV system for your needs.

1: Defining criteria – Why do I want to install CCTV?

It’s essential to start with a clear idea of what you want your CCTV system to achieve. What suits your neighbour or another business may not suit you. Are you considering the investment as a deterrent to intruders and thieves? To record access to a building or car park? To monitor movement in particular areas of your property? To record activity round the clock or at specific times, for example when your property is unoccupied? You also need to think about what you want to do with the information once you have it. How long do you want to keep it? How often do you want to review it? With clear objectives, it’s easy to determine the criteria – such as picture resolution, camera focal length and image storage requirements – that will ensure your chosen system is fit for purpose.

2: Basic requirements – What equipment will I need?

Essentially, a CCTV system comprises one or more cameras and either a software- or hardware-based image recording facility. Until recently CCTV cameras operated by transmitting analogue video signals through copper cables or fiber optic cable to a central location where the video signal was recorded. While analogue cameras still have their place, today’s more sophisticated IP cameras produce digital output and use IP networks to relay their images. The number and type of cameras you choose will depend on the subject and the extent of the surveillance area.

3: Recording options – How can I store images?

Images can be stored on the camera itself, on a computer or on a digital video recorder (DVR). The output from an IP camera is digital and is recorded without change; the output from an analogue camera is first digitised and then stored. DVRs and computer software offer the ability to record multiple channels, ie images from several cameras at the same time, regardless of the camera type. With analogue cameras, the number of channels that can be recorded is limited by the number of physical connections on the DVR, whereas in an IP system it is usually limited by software licensing. The number of camera sources you want to record from, the image quality you require, and the length of time that you want to store those images will all influence which recording device is best for you.

4: Ongoing surveillance – How can I monitor images?

A key consideration in getting the right system is to know how you want to view the images from your cameras. Will you have a central control room with trained operators constantly monitoring screens? Do you want a third-party to monitor your property? Will you want to access your CCTV images remotely while abroad? Do you want to receive email or text alerts if suspicious activity is detected by your CCTV system? IP cameras can be connected to the internet to relay images anywhere, and both IP cameras and DVRs have the capability for motion detection.

5: Static or not – Do I need fixed or moving cameras?

Camera housings can either contain fixed cameras, trained on a single location, or PTZ (pan/tilt/zoom) cameras that can rotate 360° and provide pre-programmed ‘tours’ of an area. Motion detectors can be added to a PTZ camera system so that the camera can respond and focus in on suspicious activity. Depending on the rationale for your CCTV system, you might want a mixture of fixed and PTZ cameras to cover different zones and applications.

6: Camera features – Do I need IP or analogue cameras?

While an analogue camera is ideal if you want to monitor one location from a fixed position, an IP camera is more flexible and can enable more sophisticated surveillance, recording and review. IP cameras can deliver high definition or megapixel images, which give greater detail and can cover a greater range. They can also be powered over a network using Power over Ethernet (PoE), so do not require a separate power supply. Some IP cameras have audio recording built in which allows recorded messages to be broadcast automatically to warn people that they are being watched. However, this functionality can be integrated into any camera’s housing and is not a specific benefit of IP. Both types of camera can also feature infrared technology to capture full-colour images during the day and black-and-white images in low light or even complete darkness.

7: Intelligent security – Should I integrate my CCTV with my other security systems?

CCTV cameras can be easily integrated to enhance your security. When integrated with an intruder alarm, your CCTV system can be set to record images at a higher resolution when the alarm is set or activated. When integrated with an access control system, CCTV can provide additional visual verification that a person has authorised access. Your specific integration requirements will influence the type of camera and recording equipment you need.

8: Investing wisely – How do I make the most of my budget?

This depends on what you want your CCTV system to achieve. IP cameras are more expensive because their image quality is better and they are more flexible, but analogue cameras are often sufficient for the job. If you only need fixed-point monitoring, a low-spec, low-cost analogue system would be the right choice. On the other hand, if you need to monitor a large area, it may be more cost-effective to use one high-resolution PTZ camera in the place of several fixed analogue cameras.

9: Going digital – Should I upgrade to a digital system?

The need to upgrade will depend on what equipment you already have, your surveillance requirements and your budget. By replacing a VHS video recorder with a DVR, the feed from existing analogue cameras can be digitised and more easily stored. The system can then benefit from features, such as motion detection, which are supported by DVRs. IP cameras can also be introduced to work alongside analogue cameras allowing you to benefit from their technology where appropriate.

10: Industry validation – What accreditation or references should I look for in a CCTV installer?

Credible CCTV installers will have industry accreditation such as recognition by the NSI (National Security Inspectorate) which promotes compliance with relevant British and European Standards as well as the requirements of the police and the insurance industry. A reputable company will not have any problem with you asking for their credentials, and should also be able to introduce you to existing customers for reference.

Unless you have received a personal recommendation, choosing a security company can seem daunting. Searching on the internet can present you with a wide choice of companies, all seeming to provide what you want. So how do you decide which one to choose? Your success in making the right choice depends on two key activities: thoroughly researching what functions and service you will get in return for your investment, and correctly assessing the expertise and professionalism of the company you choose. Here are the top ten criteria you need to investigate along with the questions you need to ask to be confi dent of making an informed decision.

1: Reputation – How long have you been in business?

A company that has been in business for some time will be well-tested and have a relatively large customer base. It is also more likely to be able to weather a diffi cult economic climate and less likely to fold leaving you to repeat your selection process or write-off any of your investment. Can the company tell you how many customers it has? Can it provide you with customer testimonials?

2: Product knowledge – What product ranges do you use?

Products and technologies are constantly changing. Try to establish how knowledgeable your prospective security company is, what product options and choices are available to you, and how the company embraces new technologies. Ask what areas of security it covers – alarms, access control, CCTV, and so on, and be confi dent that they can meet any future requirements you may have.

3: Customer-centric advice – How do you decide what is best for me?

A company that sees itself as a trusted advisor should help you decide what’s right for you and not try to impose a one-sizefi ts-all solution – the right solution might not necessarily have all the features that are available. Make sure when you receive your estimate that the company has really listened to your requirements and taken into account your budget and any other constraints you have stipulated. If you are in a listed building, you might want to deal with an installer that has experience working in this kind of environment and understands the challenges it may present.

4: Breadth of service – What sort of ongoing customer care do you provide?

Regular maintenance of your security system will ensure peace of mind and should avoid the need for expensive
emergency call-outs. Reputable companies will offer a range of service levels to suit your budget and the system being
installed. They should be able to offer a committed date and time for maintenance visits. Ask whether there is a dedicated customer service function and fi nd out how they handle customer calls out of offi ce hours – do you have to call a mobile number or is there seamless continuity of service via a landline? Will they come out at weekends? Do they guarantee 24/7 support 365 days a year?

5: Tailored security – Can you offer a system design service in-house?

If you have more complex security requirements, you will probably want to choose a security company with a specialist design team, experienced in producing bespoke solutions. These specialists should also be able to advise you on legal requirements (such as privacy issues related to CCTV), and health and safety issues. The better companies will be able to create CAD (Computer-Aided Design) drawings so that you can properly visualise the fi nal installation and can accurately assess the impact and viability of different options.

6: Staff quality – How do you ensure your employees are trustworthy and competent?

The staff of your chosen installer may come into your home or business and have access to passwords and security codes to physical areas and computer systems. You need to be absolutely certain that they are trustworthy. Does the company carry out police checks on its staff? Equally important is the staff’s ability to resolve problems and deal with any issues you may have. How does the company train its staff? Is it endorsed by any third parties such as Investors in People, the national standard for investment in training and development? You may also want to check how the company complies with health and safety requirements, and the levels of public and product liability insurance it carries.

7: Responsiveness – How quickly can you get back to me?

Asking for a quick turnaround on your quote can be a simple and effective way of assessing how rapidly the company is likely to respond if you need to call on it in future. Can they give you a price the same day or next day? Ask what their process is for responding to emergencies. Do they guarantee response time?

8: Total cost of ownership – What additional charges am I likely to incur?

Don’t automatically plump for the company which comes in with the lowest quote. It is highly likely that a company charging more will also give you more in the long run. Ask for a detailed specifi cation of the equipment and ask whether you will own the equipment or be leasing it. Secondly, fi nd out if the cost covers other customer and support features such as technology upgrades, handover training, and ongoing maintenance and monitoring. You should also check how long the warranty lasts and what exactly it covers. What, for example, will happen if something goes wrong and you need to call someone out as an emergency – how much will you be charged? For commercial installations, can the company provide training to new staff in the future?

9: Industry validation – What industry accreditations to you have?

If the company has a sound foundation and follows best practices it will no doubt have some sort of industry accreditations. There are several badges that you could look for but some of the best are Gold awards from the NSI (National Security Inspectorate) which promotes compliance with relevant British and European Standards as well as the requirements of the police and the insurance industry, and membership of the FSA (Fire and Security Association) which works to improve professionalism in the industry by supporting the development of technical and occupational standards, apprenticeship schemes and training programmes. A reputable company will not have any problem with you asking for this information.

10: Testimonials and references – Can I speak to your existing customers?

There are two advantages to being put in touch with a company’s existing customers. One is that it demonstrates the company’s confi dence in its work and service. The other is that it gives you an opportunity to delve a bit deeper into what level of service you can expect. Clearly the company is unlikely to get you to speak to someone who says they wouldn’t recommend it, but you can look into how smooth the whole process was by asking about aspects such as how the company behaved if they were going to be late – did someone phone to let the client know? Was anything damaged during installation and, if so, did the company make good? Most importantly, would the customer use the company again?