What is HD Over Coax, and Will It Work For Your System?
If you’ve heard the term HD over Coax or (HDoC) but were confused as to how it works, you’re not alone. HD-over-Coax is a method of transporting high-definition video over traditional analog coax cables, an easy way to carry HD signals without needing to upgrade entirely to digital equipment.
HD-over-Coax is a standard created specifically for the CCTV industry; HD-over-Coax cables contain video, audio and data, transmitting them simultaneously over a single coax cable that makes installation and repair far easier. They are also capable of two-way data transmission, and since they are analog, signals are uncompressed and free from crosstalk and signal interference. This means that one single cable can control camera functions, such as pan-tilt-zoom, even on an analog system, and cuts down drastically on how much wiring needs to be installed.
What Are HD-Over-Coax’s Technical Specs?
HD-Over-Coax works with two specifications – 1080p and 720p – and is designed to provide low signal distortion over long distances. In fact, using the proper cables (Rg59) HDoC can transmit over distances as long as 1800 feet. Compare that to distances of about 1000 feet for a traditional analog coax cable and about 350 feet for an IP/megapixel standard.
Transmission distance will also vary depending on resolution and quality; 720p video on HDoC will carry further than 1080p video, due to the lesser file size and bitrate. On a 75-5mm camera, for example, a 720p video signal can go as far as 2132 feet; 1080p video, over the same gauge cable, will only run about 1300 feet.
To help with such long-distance signals and transmission, HD-over-Coax cables includes Auto Signal Compensation, which helps provide less signal distortion over long distances.
Pros and Cons of HDoC
As popular as IP and digital CCTV systems have gotten over the past few years, analog systems still dominate, as most facilities and buildings with older systems have yet to actually upgrade to newer, digital and HD systems. Doing so necessitates removing all analog devices and wiring in the building and replacing it with digital wiring. HDoC does not; without the need for new wiring or installing an IP system, an analog system can simply be upgraded from SD to HD with new HD cameras, as well as with an HDoC DVR in place of the old DVR – while still using coaxial cables.
When it comes to saving time and money, going with an HD-over-Coax upgrade is often the easiest option. And while many IP systems are limited in their range by the Ethernet cables transmission distance (about 328 feet), HDoC cameras can, as previously mentioned, transmit in excess of 2000 feet.
HD-over-Coax’s biggest limitation right now is that it cannot support resolutions above 1080p. With many IP systems already moving past such lower resolutions in favor of 1440p or in many cases 4k, this does limit the cameras and resolutions one can work with.
Second, HDoC is not capable of supplying power; IP systems are capable of Power-over-Ethernet (PoE), which is one of their many advantages. HDoC thus requires a second cable for power, in addition to the coax cable carrying video and data feeds.
So Is HDoC Worth It?
HD-over-Coax might be a worthwhile option for upgrading your old analog system to HD, if you’re on a limited budget and don’t need the full capability of a digital system. Since HD-over-Coax can be easily integrated into your existing analog system, without needing new wires, it can be an excellent way to save money and installation time. It’s also possible to upgrade only certain parts and devices in your system, creating an analog system with both HD and SD cameras running to one DVR.
Where installing HD-over-Coax does not make sense, however, is in a system where you will likely be upgrading to full digital HD cameras in the future, anyway – as you will not be able to use any of the new HDoC cameras or wiring. It’s also not a solution when you need resolutions higher than 1080p; if you’d like the power of a 4k camera, you will need to go with a digital IP CCTV system, though it is possible that higher-resolution cables could be available in the future. There will also likely be less support and fewer compatible components for HDoC moving forward, as manufacturers and integrators continue to move towards digital systems.