The choice of transmission between cameras and DVR is often ignored, with performance consequences.
When companies look at installing a CCTV-based security system, they often find themselves caught up in discussions around image resolution of the cameras or the capacity of the digital video recorders (DVRs). Few potential CCTV end-users are aware that the choice of transmission between cameras and DVRs is in some ways even more influential when it comes to making a purchasing decision around a state-of-the-art security solution.
At the end of the day, data-transmission methods are very important. Zane Greeff, technical director of Elvey Security Technologies, a company that specialises in a number of video transmission solutions, explains that prospective end-users need to view the choice of transmission method as the technology that connects all surveillance devices together.
“As such it is important to note that a substantial amount of material and labour costs may be attributed to the laying of cables; and that, depending on the applications, the choice of transmission will determine how far each device can be positioned without compromising image quality,” he says.
So what is the way forward? In today’s market, there are five transmission technologies available – coax, UTP analogue, IP (Internet Protocol), wireless and fibre. While each has its advantages and disadvantages, it is worth examining each of these technologies in more detail to ensure we can maintain a balanced perspective for the buyer.
A dated transmission platform that deteriorates over a relatively short period of time. Moreover, it is subject to interference from various sources. Coax is also expensive to purchase (due to copper price fluctuations), difficult to install, expensive in cable containment (trays, conduits and trucking) and will need replacing if/when an upgrade to IP is considered.
Analogue on UTP
Analogue on UTP cable provides customers with the best of both worlds. What this means is that an end-user can enjoy IP connectivity (RJ45), plus all the advantages real-time analogue choices. This means users can enjoy a number of low light and cost-effective options – from multiple vendor device choices as well as the ability to transmit various signals down one multipair cable, including LV power, data (telemetry) and contact (alarms, access control).
What is more, UTP provides a suitable future infrastructure for migration to IP. And that is not all, UTP also offers immunity to interference and substantial noise rejection circuitry that ensure the exclusion of picture distortion and poor recordings – depending on the UTP transmission used.
IP-based camera systems are here to stay. On paper, the technology has a number of inherent advantages over some competing technologies. However, IP systems are restricted to the 90 m to 100 m rule and can be subject to latency issues (bandwidth restrictions) in which vital information may be lost in missed frames. With a premium UTP system, all these obstacles can be overcome. Moreover, a combination of analogue and IP over UTP can be an option often overlooked. It does not have to be one or the other.
Unfortunately, there are other disadvantages of IP cameras that outweigh the benefits. The jury is still out as far as IP’s reliability for use as a high security option with possible bandwidth issues, confidence with integrators installing and maintaining an IP network, total cost of ownership, restrictions in quality (external, low light, switchable) etc. Above all, IP-networks are not that secure and may be accessed by outside elements.
This transmission technology may be used where free space transmission is a problem. From the wireless receiver point, you still have an option to transmit up to 1,6 km in full colour transmission on an active-to-active UTP transmission system (although not all UTP devices can manage this range). Monochrome picture can be transmitted much further as there is no heavy colour burst issues.
For companies looking to transmit CCTV data over very long distances, often the economical and practical choice can be resolved by a fibre backbone. However, rather than come off in fibre and terminate into the camera (often the most expensive part of the fibre installation), many customers choose to use UTP. One could only achieve distances of up to 1,6 km from the fibre backbone point.
Overall, UTP appears to offer customers the most in terms of value add, says Steve Proctor, sales director of NVT. “Twisted pair cabling is always used in data and telecommunications networks for short and medium length connections because of its relatively lower costs compared to optical fibre and coaxial cable.”
Simple, easier to install and hugely flexible, UTP cables look set to have a major impact on the local CCTV industry.
If this is the case, why has the technology taken so long to arrive on our shores?
Kenny Chiu, marketing manager of Elvey, says that UTP has been around for a long time. “Traditionally it is seen as an analogue-friendly data transport medium and with the ever growing popularity of the Internet; it only seems natural that all systems migrate to a digital-friendly technology. However, analogue is a proven technology and transmitting data over UTP can also provide benefits most end-users would consider when purchasing an IP/fibre system – but for a much lesser cost.”
Compared to an IP-based system UTP is also inherently secure, a feature that is of paramount importance for any company seeking to install a CCTV system for security purposes.
Another key benefit of UTP is that it costs less per metre than any other type of LAN cable. In the real world, this translates to companies spending less on cabling and more on actual end-user security devices. “End users of UTP cabling-enabled systems will always receive quality video signals whether the camera is 10 m away or 1 km away,” he explains. “Both devices will have perfect picture continuity and performance, as well as immunity to interference and substantial noise rejection as the circuitry features exclude picture distortion and poor recording possibilities,” Chiu says.
UTP also opens up possibilities in terms of extension. “Spare pairs are easy to accommodate at little or no extra costs – much like telephone extensions – the spare pairs are already there. In all active units there is also built-in ground lifting (ground loop isolation) features which normally have to be purchased separately.
“It is easy to see that UTP affords the end-user a wide range of benefits. It is convenient, simple to use, and offers high-quality video transmission. This ensures that customers now have the option of choosing a viable, competitive and future-proof solution that can be easily extended, or finally migrated into a full IP solution,” he concludes.
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