Security networks are evolving - both in terms of how surveillance data is captured and how it’s transported. In this 'Viewpoint' we take a look at the issues that affect the choice of transport and some of the typical transmission challenges faced by organisations.
Data delivery should be viewed as the pace car in the race to faster, more advanced security systems. In other words, no matter how powerful your endpoint technology is, the way you transport data from A to B will determine what will work on your network. But as technologies such as uncompressed, high definition video make their way in from the professional video market, and users demand the same flexibility from global surveillance systems as that afforded by their internal IT networks, that pace car may well need a co-driver plus a full tank of rocket fuel.
A Question of Connectivity
Let’s face it; in a CCTV system, connectivity, or transmission, doesn’t exactly grab the limelight. Interest is focussed on the cameras, the control room, system storage, recording capability and, increasingly, on video analytics. Then come capital outlay and ongoing maintenance – just about everything apart from the transmission. Once a consultant or system integrator is involved, transmission options may be addressed, but even then, the concern is usually for cost rather than performance. When the attention finally does turn to connectivity, users are faced with a bewildering array of options and terms that can mean very little to them.
Classifying Transmission Systems
The logical approach to evaluating transmission is to classify first by the interface at the camera: analogue, IP or high definition and then by the transmission medium.
System Interface
Analogue: An older technology, based on an analogue composite video signal, analogue is simple, straightforward and low cost. It provides perfectly good system operation with good quality images; however it’s less flexible than IP.
IP: The current technology, IP can provide a one-to-one or one-to-many system. It’s often regarded as complicated, but provides greater flexibility, and allows different systems to be integrated onto a common platform. For the purists, IP is not a transmission interface...what we’re actually talking about is Ethernet.
High Definition Video: Classed as an emerging technology, it stands to reason that with high definition TV at home, users are beginning to demand high definition video in their control rooms as well. Many camera manufacturers now offer uncompressed digital video outputs on their units. This High Definition video should not be confused with HD-IP interfaces, which offer a compressed HD signal in an IP format.
Transmission Medium
Once the system type is resolved, the physical media for the transmission needs to be chosen. You need to consider four factors:
- Medium availability: Is there cable and/or spare capacity? Is there WAN access? Could wireless be used?
- Performance: Transmission distance, bandwidth, signal integrity, susceptibility to noise, capacity for expansion
- Cost: Includes the transmission and the infrastructure costs (digging up the roads etc.)
- Environment: CCTV cameras, by their very nature, are usually located in non-conditioned environments, so transmission equipment must be able to withstand extremes of temperature, humidity, shock and vibration. This is especially important in IP CCTV systems. The temptation to install commercial grade products in a non-conditioned environment will very soon result in system failures.
Transmission Options
Currently, the choices include the following (or a combination of them):
- Copper: the default – relatively low cost but has transmission limitations, is susceptible to noise and can be tapped into.
- Fibre: offers much higher bandwidths, it’s lightweight, secure and immune to noise.
- Wireless (point-to-point, point-to-multipoint & mesh): ideal for where it’s not possible or practical to cable.
- Cloud / WAN / 3G: offers great flexibility and a can significantly reduce transmission costs.
- Microwave: highly directional - the main issue is the licensing which increases the cost.
- Free Space Optics: again highly directional but can be very expensive.
At Lanode we have expanded our relationship with KBC Networks and whilst their products are also designed for industrial control, site management and intelligent transport systems, the prime focus is on security and CCTV systems. The range is industrially rated, with wide operating temperature ranges and hardened casings; covers IP, analogue and high definition, and spans copper, fibre, wireless and WAN.
KBC use a number of technologies across their 4 major product ranges: network (IP), wireless, analogue fibre, and digital video broadcast (high definition video).
IP Transmission Systems
The transition towards IP in the security industry has introduced opportunities for expanding networks and lowering infrastructure costs. IP systems undoubtedly bring greater flexibility however, with that flexibility, comes a whole new set of challenges as systems become more complex.
The WAN Challenge
IP video systems are designed to optimise mega-pixel and standard camera imaging. In addition to incredibly accurate live viewing, the systems provide a suite of management and analytical tools. However, the majority of these systems are designed to operate on a LAN. If the system is required to operate across a WAN, it’s likely that firewall restrictions will inhibit many of its basic functions. The response to this might be to open up multiple ports at each end of the link and to configure port forwarding rules for all open ports, but once you start opening up ports on a firewall, your system will be exposed to security threats.
A further challenge in the transition from LAN to WAN involves the ‘Time To Live’ (TTL) levels set in the header of the data packet. The TTL level is decremented every time a packet passes through a router. Once it reaches zero, the packet is discarded. This ensures that lost packets don’t clog the internet. In many cases, the encoder manufacturer sets the TTL at a low level. Send that packet over the internet and, very soon, it will pass through enough routers for the TTL to reach zero and the packet will be discarded never reaching its destination. Other problems that may be encountered include blocking multicast packets and high latency in, for example, satellite links.
How do you Configure a CCTV System over the Internet?
The safest way to implement a video system over a WAN is to create a VPN (Virtual Private Network). This, as the name suggests, is a virtual tunnel through any network. By utilising enhanced communication algorithms, and encapsulating the data, it will place all IP CCTV equipment within the same Virtual LAN, eliminating most firewall issues. The issue of sending sensitive data over any public network can also be overcome by adding encryption to the connection, using Blowfish, AES or Camellia.
Unfortunately, creating a secure VPN can be far from straightforward; it’s a job for skilled IT specialists to both configure and maintain a VPN which will incur an ongoing cost. And, if it’s carried out at the router, i.e. a software-based VPN, additional processing overheads will be introduced to the router.
ThruLink™, a Simple Solution to Complex Transmission
Developed by KBC Networks, ThruLink is a hardware VPN. It’s industrially rated and takes someone with even the most basic IP understanding just a few minutes to configure. It requires no ongoing maintenance and only requires a single port forward rule to be set up. ThruLink offers end-to-end encryption up to 256bit, ensuring security across the link. Once established, the system constantly monitors the link’s bandwidth and latency, making minute adjustments to its settings to optimise the channel.
Wireless Security Systems
Despite a legacy of users and installers wary of security and reliability, the current generation of wireless transmission products provide fast and cost-effective transmission that is both reliable and secure.
Wireless systems are used for three main reasons: the infrastructure cost is significantly lower than installing cable; in settings such as city centres, or historical sites, it’s simply not possible to lay cable, leaving wireless as the only option, and installation is fast and flexible, so it’s ideal for temporary deployments. In addition to fixed systems, wireless transmission is commonly used for mobile systems, to either stream live video from patrol vehicles to a control centre, or to view live video or retrieve data from a CCTV network.
Analogue Fibre
Despite the march towards IP and high definition, analogue systems still make up a large percentage of the CCTV market. KBC’s analogue fibre range - ASFOM (Application Specific Fibre Optic Modem), is a bespoke, multi-interface series that allows you to choose the exact number and mix of signal types within a unit. It covers singlemode and multimode fibre and is designed for maximum channel density with the minimum footprint.
Full HD-SDI Video – the Next Generation of CCTV Systems
The benefits of high definition surveillance systems are substantial, allowing detailed images to be captured in real-time over a wide field of view for extremely accurate display, recording and analysis. With its simple 75Ω coax interface, which is similar to that used for analogue composite video, HD-SDI is becoming the de facto interface for HD CCTV systems. Many see the technology as a viable replacement for standard analogue, however with much greater signal bandwidths, transmission over a copper system is significantly curtailed.
Hybrid Transmission - All of the Above
Simply put, a hybrid system uses multiple transmission media, such as fibre, wireless, copper and WAN, to transmit data across a network. In a hybrid system, the characteristics of each part of a network determine the medium, each posing a distinct transmission challenge. Many hybrid networks cover large areas, remote locations and varying terrain, so for example, if a network needs to incorporate cameras across a campus, wireless Ethernet links provide an ideal solution. If some of the cameras are located a significant distance from the control room and dark fibre is available, the signals can be brought in over that fibre. Video from remote cameras may also be brought in via a WAN.
Summary
The range of transmission interfaces and transmission types now available in the security industry has introduced opportunities for companies to truly customise their security networks. Increasingly we see requirements to extend networks over regional, country and now continental boundaries. With a product range that spans analogue, IP and high definition, with KBC Networks we are able to let the end users’ requirements and the characteristics of the environment dictate the best medium for transmitting the signal. And with the breadth of the product range that KBC Networks and Lanode now offers, who said transmission was boring?
Source: Extract from original article content created by Iain Deuchars from KBC Networks
Used with permission
