How to network ... by degrees

digital solutions, IP-based CCTV solutions have enormous benefits to offer the installer and his clients. Numerous misconceptions about IP systems continue however. In this article we address some of the key issues and argue that your clients would benefit from utilising a degree of IP technology with their existing CCTV installations.

   Currently, tens of thousands of organisations have an existing analogue or digital CCTV system and, quite separately, a local or wide area network for their existing data and possibly telephony communications. In all of these environments it is possible to integrate the existing analogue or digital CCTV system with the existing local or wide area network, thereby delivering the benefits of IP CCTV to the end user.

Scenario 1 (right): Viewing analogue images over a network via a DVR

This is the simplest ‘hybrid’ configuration in which analogue or IP camera inputs are fed into a DVR which itself is connected to the network. This enables staff in a multi user environment to view live and recorded images on an existing CAT5 data network on any PC connected to the network using browsers.

Scenario 2: IP cameras and conventional coaxial analogue cameras combined over

an existing network

This example shows how easy it is to add an existing analogue CCTV system to an existing IP network. Once combined with the existing data network, the analogue CCTV system in this example has been extended to include a variety of IP cameras and domes.

A remote user is shown dialling into the network via ADSL and viewing the images in a web browser, and a standard PC user is shown viewing the images on the network utilising viewing/recording software within the office.

Depending on the software employed the users, whether office-based or remote, can manage all aspects of the CCTV security system including camera viewing, recording, motion detection and alarm monitoring.

To achieve this configuration each camera needs to be added to the network. This is achieved by passing the analogue signals from the camera through a network video server which encodes the signal so that it can run over the network.

Note how analogue coaxial cabling carries the signal into the network video server, and the existing IP cabling is used between the server and the network. This represents one of the most significant benefits of IP CCTV – the ability to capitalise on the existing network used to run the company’s existing data communications. Recorded images are stored on a server connected to the network, not a traditional VCR or digital video recorder.

Scenario 3: Combining conventional tele-metry control and domes over a network

A common misunderstanding with clients is that their existing investment in telemetry control is sacrificed if their existing analogue or digital CCTV system is added to an IP network. In this scenario, we illustrate how it is possible to continue with an existing telemetry control operation and add an existing analogue or digital CCTV system to an IP network.

Each analogue camera is connected to a network video server for the analogue signals to be encoded for network use as in the previous example. On leaving the network however, the encoded images are decoded on another network video server before returning into the analogue matrix.

The benefit of doing this is the ability to utilise the telemetry keyboard (with proportional speed joystick) to move the domes, thus providing an alternative to a QWERTY keyboard and mouse.

It isn’t necessary to have a separate server for every camera, as network video servers with multiple video (camera) inputs are now available.

Network availability

Concern about the impact of image files on network availability has dogged the growth of IP. From the CCTV perspective, security managers are concerned that a busy network might prevent images from being recorded successfully and securely. IT managers are concerned that large image files might impede other traffic using the network. The bandwidth required to run a CCTV system over IP depends on a number of factors, including the compression method used, the cameras’ application and the total number of cameras in the system.

   H261 and Wavelet compression require lower bandwidths than, for example, M-JPEG. Newer compression techniques such as MPEG-2 and 4 are rapidly becoming more common, requiring substantially greater bandwidths by comparison. All of these techniques can be optimised to perform within, or limited to, the available bandwidth. Different applications have different priorities regarding clarity of the image, data volumes, and processing power – for example identification evidence requires a higher picture quality compared to monitoring the length of a queue. So for each application there is a suitable compression method. Different formats cannot communicate with each other, so a careful choice needs to be made to ensure the selection of the most appropriate product, and therefore compression format, for the installation.

Depending on the compression technology used, the average M-JPEG IP camera generating full streaming images will require approx 1.5Mbits/s per channel – that is equivalent to 1.5 per cent of a standard corporate network’s bandwidth (100Mbits/s).

Another aspect affecting bandwidth is the use of controls to segment and prioritise CCTV traffic to reduce its impact on LAN traffic levels. For example, the technology exists to multicast a CCTV signal, enabling the use of a single video feed by multiple users, greatly reducing traffic levels. The implementation of this and other traffic management techniques will become more widespread as IP knowledge and experience grows in the installation industry.

Adding CCTV to an existing network need not create network availability issues either for users or for the CCTV recording system itself.

Supporting the industry

One of the exciting aspects of IP CCTV is the cross-fertilisation of skills between traditional CCTV installation engineers and IT professionals, network integrators and end user in-house staff. In the past this has created concerns because these two worlds – CCTV and IT – are historically very different. As IP CCTV grows in popularity though, these two worlds are rapidly learning from one another and many of the misconceptions of both industries are being reassessed. Having deliberately recruited staff with both traditional CCTV and IP backgrounds, Video Imaging Supplies is ideally placed to assist this process of mutual education.

   Installers need assistance with IP technical support, and network integrators with support on issues such as lenses and PTZ control, the relevance of which might be overlooked by ordinary IT distributors.

As we supply traditional analogue, digital and IP solutions, installers, network integrators and end users can be confident that they are receiving high quality advice and support. 18 months ago, a discussion on IP might have suggested analogue was dead and even the traditional DVR market was considered vulnerable to wholly IP-based surveillance systems. Experience shows us the growth in IP is as rapid as predicted but more subtle and sophisticated in its application than might have been foreseen. Analogue, digital and IP systems have a collaborative future. This means a double benefit, with past analogue and digital investments in CCTV fully protected while new investments deliver the full benefits of IP.